Research support for new uses and improved production of deer velvet - Suttie JM; Haines SR; Clark DE; Archer JA; O'Connor M; Broeder CE; Corson ID (Proceedings of the New Zealand Society of Animal Production, 2005)
Deer velvet is a novel agricultural product and has presented the New Zealand (NZ) agricultural and food sectors with a number of opportunities. When the velvet industry emerged in the early 1970s, almost the entire product was exported to the traditional oriental medicine markets, which remain the basis of the deer velvet industry in NZ. This market did not require scientific validation of efficacy as the health promoting effects of velvet were accepted. However, as this is a mature market there is interest in growing new business, notably the Western dietary supplement market. This requires new knowledge on health benefits as potential purchasers have no initial product knowledge. We have conducted research to investigate whether or not deer velvet will help promote health. We chose to look for a verifiable benefit to athletes as the athletic market would be less likely to be price sensitive than other sectors. We also investigated the application of specific velvet extracts as topical agents to promote healing of open wounds, based on their ability to promote the growth of blood vessels (angiogenesis). This paper discusses the research that set out to demonstrate velvet efficacy and quality and describes research on nutrition and breeding designed to increase velvet quality and quantity. KEYWORDS: deer; velvet; antlers; production; quality; wound healing; dietary supplement; health benefits.

The role of suckling on the parasite status of very young lambs infected with Teladorsagia circumcincta - Iposu SO; Greer AW; McAnulty RW; Stankiewicz M; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 2005)
This study investigated the importance of suckling for the resistance and/or resilience of very young lambs to Teladorsagia circumcincta nematode infection. Thirty, 6-week old twin-born lambs were allocated to four treatment groups in a 2 x 2 factorial design in which groups continued to suckle (S-) or were weaned (W-), and concurrently not infected (-N) or infected (-I) with 1000 L3 larvae of T. circumcincta per day while grazing ‘clean’ pasture for six weeks, and then slaughtered. There was a significant infection by time interaction on faecal egg counts (FEC; P < 0.001). Suckling/weaning had no effect on FEC. Worm burdens were similar in suckled-infected (SI) and weaned-infected (WI) lambs (8029 + 1502 vs 12228 + 1704 worms, SEM; P > 0.05), respectively. Eggs per utero were significantly greater (29 + 6 vs 15 + 1 eggs, SEM; P < 0.05) in SI than WI lambs, while length of female worms was similar in both groups (10.2 + 0.2 vs 9.7+0.3mm, SEM; P > 0.05), respectively. The two suckled groups progressively gained more weight (P<0.001), while uninfected lambs of both groups were heavier (P < 0.05) from day 28 onwards. Weight gain averaged 122, 282, 98, and 240g day-1 for the WN, SN, WI, and SI lambs, respectively. The study has not shown any advantage of suckling while grazing for lambs’ resistance or resilience to larval intake within the 12-week post lambing period. KEYWORDS: Teladorsagia circumcincta; suckled lambs; resistance; resilience.

Sire-line differences in lamb losses from starvation exposure - Gudex BW; Hickford JGH; Frampton CM (Proceedings of the New Zealand Society of Animal Production, 2005)
Sire-line differences in neonatal lamb mortality due to starvation-exposure (diagnosed using basic ‘on farm’ observations) were observed in five trials (1390 lambs in 15 sire-groups). After correcting for variations in lamb birth weight and in the cold challenge experienced by each lamb using logistic regression, sire-line differences in lamb mortality due to starvation-exposure were detected in flocks where the cold challenge and the number of progeny in each sire line was sufficient (P < 0.05). Although sire-line differences in lamb mortality due to starvation-exposure were detected independent of birth weight, the analyses revealed that birth weight is still the largest influence upon lamb mortality due to cold exposure (P < 0.05). These results confirm that due to the large and contradictory role that birth weight has in influencing lamb survival, it is extremely important to record and account for it in any attempt to breed for enhanced lamb survival. The detection of sire-line differences in lamb mortality due to starvation-exposure independent of birth weight could provide a basis to select for improving lamb survival, thus raising the efficiency of lamb production.

Software for evaluating sampling strategies and error rates in the identification of mixed meat products - Vetharaniam I; Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
DNA verification of the origin of meat within traceability systems involves the comparison of DNA samples taken at a reference stage with samples taken further down the supply chain. While such verification is well established when whole cuts of meat are involved, this is not the case for mixed-meat products made from an unknown number of contributing animals. Spreadsheet based software has been developed to analyse one DNA verification scheme for determining whether a returned product did indeed originate from a particular manufacturing batch. The scheme involves the comparison of k individual DNA samples (comprising an unknown number of individuals) from the product, with a set of s DNA samples (comprising an unknown number of individuals) taken randomly before manufacture of the batch in question. The software gives the error rate for correctly matching the product to the batch, for different sampling rate combinations of the product and at the factory. Key words: DNA verification; mixed meat; traceability; sampling.

A study of mastitis in two small experimental dairy herds managed either organically or conventionally during one year - Silva KE; Quinn AK; Morel PCH; Holmes CW; Thatcher A; Shadbolt NM; Kelly T (Proceedings of the New Zealand Society of Animal Production, 2005)
Mastitis infection status of two small herds located at the Dairy Cattle Research Unit of Massey University was assessed. Single quarter milk samples from 45 cows under organic production (first and second year of organic certification) and 50 cows under a conventional system were taken on four occasions: mid lactation (these samples were frozen); prior to the last milking before dry-off (season 2003/2004); before the first milking after calving and 14 days post calving (season 2004/2005). Milk samples were cultured for bacterial analysis. Somatic cell counts (SCC) from monthly herd tests, and clinical mastitis cases were recorded and analyzed. The percentages of quarters with positive bacterial growth, and SCC, were generally higher in the organic herd, but differences were only significant for Staphylococcus aureus in all four sample periods, and for Streptococcus spp. 14 days post calving. The results suggest that in organic herds Staphylococcus aureus infections could become an important concern, because of constraints on the use of antibiotic treatments. Effective prevention of infections by this organism will be essential, in order to prevent high culling rates. KEYWORDS: mastitis; organic dairy; New Zealand.

A survey of the control and financial impact of footrot in the New Zealand Merino industry - Hickford JGH; Davies S; Zhou H; Gudex BW (Proceedings of the New Zealand Society of Animal Production, 2005)
A survey was sent to 869 Merino farmers in New Zealand in August 2001 seeking information about the prevalence of footrot, treatment and control measures applied, their related costs, and estimated production losses attributable to the disease. There were 304 respondents to the survey and they farm approximately 43% of the Merino sheep in New Zealand. Footrot was reported to be present in 59% of the respondents’ flocks with 6.4% of the sheep infected by footrot at the time of surveying. Foot bathing, culling of affected sheep and breeding for footrot resistance in flocks were the preferred control measures. Footrot treatment was calculated to cost $1.67 per Merino sheep per year with an additional $1.77 per sheep attributed to losses in animal production. Assuming the respondents are representative of the New Zealand Merino industry, the total cost of footrot to this industry was estimated to be in excess of $11 million annually.

Traceability around the world - Nortje GL (Proceedings of the New Zealand Society of Animal Production, 2005)
With the business case for a national animal identification system due in July 2005, it is appropriate to take stock and to see where New Zealand (NZ) and other countries are at with animal and full supply chain traceability. The objective should be to learn and contribute to the outcome. Full supply chain traceability is on the horizon, NZ needs to be proactive and valuable lessons are available particularly from the United Kingdom (UK) and Canadian experiences. The preferred position seems to be one where government plays a leading role without burdening the industry with yet another set of legislative requirements. For this to work effectively, the industry has to commit to traceability, to go beyond ordinary compliance type applications and to use it as a differentiator in the market place. Traceability is not going to go away, and as the requirements will continue to increase around the world, the best option is to embrace it.

Traceability contract session: Introduction - Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
Food safety issues, especially those associated with animal disease (e.g. BSE in cattle), human health (e.g. salmonellosis), genetic modification and animal welfare are driving consumer pressure for traceability of animal-derived foodstuffs. Several of our trading partners already have in place, or have signalled, expected compliance dates for meat traceability requirements. This contract session addresses some of the background as to why, and when, New Zealand (NZ) can expect to be required to have traceability procedures in place to ensure continued access to the world`s meat and animal derived foodstuffs market. The following 10 papers will also describe examples of what is currently in place or projected to become available for tracing animals on the farm, during transport and through meat processing plants both in NZ and overseas. The mix of speakers has been chosen to encompass legislative, industry and scientific aspects of traceability of meat and meat products.

Traceability databases in the New Zealand sheep industry - Cruickshank CJ (Proceedings of the New Zealand Society of Animal Production, 2005)
Sheep traceability will become a necessity in New Zealand to cover consumer, biosecurity and international trade requirements. The requirement to track individual sheep from lamb processors to the farm of birth is a major logistical challenge but is considerably easier than in some of New Zealand’s trading partners. Definition of the requirements of a traceability system and implementation into an effective model are still under debate. A major requirement is the design and implementation of a central database to cater for present and future needs. A traceability system could be developed using databases and technology already used in the sheep industry.

Traceability systems in the meat industry - Shackell GH (Proceedings of the New Zealand Society of Animal Production, 2005)
New Zealand is reliant upon maintaining export markets for the sale of a significant proportion of its meat and dairy production. Any loss of key overseas markets has significant implications for the national economy. Therefore, we are obliged to meet or stay ahead of market drivers. Increasingly, one of those drivers is product traceability for reasons of consumer confidence. While traceability systems have a relatively short history, they have traditionally been paper and/or electronic based. They are generally managed by parties with a vested interest, and their integrity is difficult to monitor. Animal products have a unique identifier, DNA, that is tamper proof. There are a number of DNA-based traceability systems around the world that are being used in the meat industry. As well as direct tracing of a meat sample back to the animal, and ultimately to the property the animal was raised on, DNA technologies are also being used on-farm for testing meat quality traits and determining the animal’s pedigree. This paper describes some of the traceability options that are in use within the environment in which New Zealand is competing for trade. KEYWORDS: traceability; meat; DNA.

An update on beef traceability regulations in Japan - Ozawa T; Lopez-Villalobos N; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2005)
An updated beef traceability system has been in operation in Japan since December 2004. This system enables consumers to check the origin of beef products, not only for table meat, but also for restaurant cuisine. The system is dependent on producers, abattoirs, meat wholesalers and meat retailers recording and managing information on each cattle beast using a ten-digit individual identification number. It would not be an exaggeration to say that the essence of the Japanese beef traceability system would not be possible without this individual identification number. Fukaya Wagyu adopted an extended traceability system by presenting detailed information which is missing in the national system. This detailed information enables a ‘face to face’ relationship to be established between the farmer and consumer. This relationship is an effort to promote the supermarket’s own brand to the customer. KEYWORDS: traceability system; beef; Japan.

Validation of the double ?-alkane technique to estimate the dry matter intake of red deer fed fresh ryegrass-based pasture or plantain - Swainson NM; Hoskin SO; Clark H; Krause M (Proceedings of the New Zealand Society of Animal Production, 2005)
The accuracy of the double η-alkane technique to estimate dry matter intake (DMI) of red deer (Cervus elaphus) fed fresh cut perennial ryegrass-based pasture (Lolium perenne cv Nui) and narrow-leaved plantain (Plantago lanceolata cv Ceres Tonic) was determined in a cross-over experiment involving five adult castrated stags housed in metabolism cages. A strong positive linear relationship between actual and estimated DMI was obtained for pasture when using both C31 and C33 (C31 R2 = 0.94; P < 0.01; C33 R2 = 0.92; P < 0.01) and plantain for C31 (R2 = 0.80; P < 0.04), but not for C33 (R2 = 0.49; P < 0.19). However, the predicted DMI of deer using the η-alkane technique was underestimated up to 27.6% for deer fed ryegrass-based pasture and overestimated up to 17.2% for deer fed plantain when compared with actual DMI. The discrepancies between actual and predicted DMI could have been partly due to a difference of 26% between faecal recovery rates of odd and even-chain alkanes with pasture feeding and 12% with plantain feeding. This suggests that the η-alkane technique may not be appropriate for estimating DMI of ruminants grazing New Zealand fresh forages, especially when comparisons between forage species are required.

What is driving the call for traceability ; where does the consumer sit? - Saunders CM (Proceedings of the New Zealand Society of Animal Production, 2005)
Traceability has increased in importance for market access over the last couple of decades. This has been driven by the BSE and other food scares. This paper reviews the history of traceability, including changing consumer preferences, and the change in legislation which has also been an important factor behind this demand. The paper then reviews various studies that have assessed consumer preferences and their willingness to pay for traceability and/or Country of Origin Labelling (COOL). In general, consumers are willing to pay extra for traceability. The reasons behind this appear to be primarily driven by demands for food safety, especially in relation to certain food scares such as to avoid BSE beef. New Zealand is in an excellent position regarding its ability to comply with these requirements.

Zearalenone challenge in sheep : urine sampling to measure response - Morris CA; Amyes NC; Sprosen JM; Hawkes AD; Finch SC; Miles CO (Proceedings of the New Zealand Society of Animal Production, 2005)
Zearalenone is a fungal toxin produced by Fusarium species commonly found on autumn pastures in New Zealand. It may interfere with reproductive functions in sheep. In a search for a genetic measure of susceptibility, ewe and ram lambs were dosed orally with a suspension of zearalenone at a series of rates, at 8 and 11 months of age. Urine samples were taken at intervals from 2 to 50 hours later. The concentration of urinary zearalenone and its metabolites (Zen) was assayed using an ELISA. Adjustment for urinary volume was made by measuring the urinary concentration of creatinine (Cr), and results were expressed as Zen/Cr ratio (loge-transformed). In a separate experiment, breeding ewes were dosed with zearalenone at a single rate, and Zen/Cr response was measured. The following effects were evaluated in lambs: a) sex difference (ewe versus ram lambs), b) responses to three dose rates, c) time-series response data. The heritability of Zen/Cr was determined in lambs and breeding ewes; results were analysed after standardising for each treatment and sampling group. Urinary Zen/Cr, 6 h after dosing, differed between ewe and ram lambs by a factor of 1.75 (ewe lambs higher; P < 0.01). Zen/Cr values for three dose rates (3, 6 and 9 mg zearalenone per lamb), averaged over three sampling time points after dosing, were 23.5, 43.2 and 59.3, respectively (P < 0.0001). Zen/Cr values for three sampling time points (2, 4 and 6 h after dosing), averaged over three dose rates, were 58.0, 35.8 and 29.0, respectively (P < 0.0001). By 50 h after dosing, the Zen/Cr average had fallen to 4% of its 2-h value. The interaction between dose rate and time of urinary sampling was not significant for log Zen/Cr. A preliminary estimate of the heritability for standardised Zen/Cr was 0.32 ± 0.10 (P < 0.01). The dosing regime reported here could be used for a test of animal response to zearalenone in ram breeders’ flocks. KEYWORDS: sheep; zearalenone; dose response; urine; heritability.

Zearalenone challenge in sheep : variation in ovulation rate - Morris CA; Amyes NC; Smith JF; Sprosen JM; Towers NR (Proceedings of the New Zealand Society of Animal Production, 2005)
Zearalenone is a fungal toxin produced by Fusarium species commonly found on autumn pastures in New Zealand, and it may interfere with reproductive functions in sheep. We have measured both ovulation rate after challenge with zearalenone, and also a metabolic indicator, Zen/Cr (the concentration of zearalenone and its breakdown products (Zen) in urine, after adjustment for urinary volume using creatinine concentration (Cr)). A small self-replacing flock of Coopworth ewes was used for the study. This paper reports a preliminary assessment of whether Zen/Cr might be an equivalent but cheaper method than laparoscopic ovulation rate for measuring an animal`s resistance to zearalenone. Ovulation rates were determined in ewes in autumn before dosing (Lap1; Years 1 and 2), and after dosing (Lap2; Years 1 to 4) with 10 mg zearalenone per animal per day for 6 days. The average reduction in ovulation rate following dosing (Years 1 and 2: Lap1 minus Lap2) was 0.60 ovulations or 31% of the mean. Lap2 was used for the present correlation analyses. The heritability of Lap2 was estimated (0.11 ± 0.09), and breeding values (BVs) for Lap2 were determined. Subsequent to the laparoscopy, the ewes were mated at pasture, and the resulting natural litter sizes were monitored in relation to BVs for ovulation rate after challenge. Urine samples were taken during and after dosing in Years 3 and 4, to measure Zen/Cr, and a heritability for Zen/Cr (0.32 ± 0.10) was estimated from these and other Zen/Cr data. Preliminary analyses of BVs for Lap2 and Zen/Cr revealed a negative correlation between them (r = - 0.55). Ewes with higher BVs for ovulation rate also had higher mean litter sizes following natural ovulation. In conclusion, zearalenone affects ovulation rate at moderate challenge levels, and this ovulation rate may be negatively related to the concentration of measurable urinary zearalenone metabolites. KEYWORDS: sheep; zearalenone; dose rate; ovulation; heritability.

Advances in maize silage genetics and crop management and the impact on the NZ dairy industry - Densley RJ; Williams ID; Miller DB; Densley DW; Sapienza DA (Proceedings of the New Zealand Society of Animal Production, 2004)
Significant lifts in profitability have been achieved by New Zealand dairy farmers through the inclusion of increasing amounts of maize silage into a pasture based system. Most of this maize is grown off the dairy unit on farmer owned or leased runoff blocks or by contract growers. While there is still significant scope to improve dairy farm productivity by increasing maize silage input levels, there is considerable opportunity to also improve dairy farm productivity by reducing feed costs through improving maize silage yields, increasing milk output by lifting maize silage nutritional quality and improving agronomic stability of maize silage offering higher yields over a wider environmental range. Traditional plant breeding, genetic engineering and advances in agronomic management all have the potential to impact production potential and profitability of maize silage in New Zealand dairy farm systems.

Anthropometric, metabolic and endocrine evaluation of children born following assisted conception and methylation analysis of imprinted genes - Miles HL; Peek J; Hofman P; Harris M; Billett N; Graham F; Birdsall M; Fisher R; Cutfield W (Proceedings of the New Zealand Society of Animal Production, 2004)
Numerous studies with New Zealand beef cattle have been carried out to determine responses of live weights or reproductive/survival traits to changes in the level of nutrition, at various stages during the annual production cycle. Various studies have also been carried out to describe how much of the variation for these traits of the cow or calf is genetic. This brief summary explores the possibility that some of these cattle data could be re-evaluated because of their possible relevance and analogies to current medical questions of interest.

Are elevated maternal thyroid hormone concentrations after-mid-pregnancy shearing responsible for changes in lamb fleece characteristics? - Kenyon PR; Sherlock RG; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2004)
This study was designed to test the hypothesis that elevated maternal thyroid hormone concentrations in mid- pregnancy are responsible for the observed differences in lamb follicle characteristics as a result of mid-pregnancy shearing. The study involved 51 twin-born lambs in a 2 x 2 factorial design involving dams that were either shorn or unshorn in mid pregnancy and had either normal or elevated thyroid hormone levels. All ewe groups were thyroidectomised except for unshorn-normal ewes which were sham-operated. The thyroxine implant and injection regimes used to manipulate maternal thyroid hormone levels in mid-pregnancy were successful in mimicking the levels previously reported in mid-pregnancy shorn ewes. Lambs born to shorn dams had significantly (P<0.05) higher coefficients of variation of mean fibre diameter. Dam shearing treatment had no effect on any other follicle or wool characteristic. Lambs born to ewes with elevated thyroid levels in mid-pregnancy had a significantly (P<0.05) higher numbers of secondary fibres, and tended to have more primary fibres (P=0.08) and whiter wool (P=0.06). The absence of any dam shearing-treatment effect on secondary and primary fibre numbers, fibre diameter and length, suggests that the changes observed in follicles and wool characteristics of lambs born to mid-pregnancy shorn dams are primarily due to elevations in maternal thyroid hormone levels in mid-pregnancy. More work is required to confirm this hypothesis.

Can mating ewes on condensed tannin-containing forages be used to reduce lamb mortality between birth and weaning? - Barry TN; Parkinson TJ; Ramirez-Restrepo CA; McWilliam EL; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2004)
Five grazing experiments are described where ewes were fed forages which are likely to increase the absorption of essential amino acids (EAA) for periods of 63-70 days, immediately before and during mating, relative to control ewes mated on grass based pastures. The legume Lotus corniculatus (Birdsfoot trefoil CV Grassland Goldie) was fed in two experiments and supplements of willow or poplar forage trees were given to ewes mated on low quality drought pasture in three experiments. Both L. corniculatus and the forage trees contained condensed tannins (CT) and in addition the crude protein content of the forage trees (166 g/kg DM) was much higher than that of drought pasture (122 g/kg DM). Mating on L. corniculatus and supplementing with forage trees consistently increased lambing percentage. Lamb mortality between birth and weaning was significantly reduced (P<0.05) by mating on L. corniculatus in one experiment and by feeding forage trees during mating in one experiment. Similar trends of smaller magnitude were evident in the other experiments and did not attain statistical significance. Hypotheses of how feeding these forages during mating may have reduced post-natal lamb mortality are advanced and methods of testing the hypotheses are suggested.

Can we use change in core body temperature to evaluate stress in sheep? - Beausoleil NJ; Stafford KJ; Mellor DJ (Proceedings of the New Zealand Society of Animal Production, 2004)
Physical and psychological stressors are known to cause a transient increase in the core body temperature of mammals. We hypothesized that rise in core body temperature could be used to indicate the intensity of stress experienced by sheep. Based on established indices of stress, we ranked five treatments from very low to severe stress as follows: Holding with flock mates, Human presence, Visual isolation, Capture and inversion, and Simulated shearing. Change in core body temperature was measured remotely using thermal sensors placed in the ear canal of the sheep. Maximum change in core body temperature (p=0.08) and the area under the core temperature change curve (p=0.09) allowed differentiation of the least and most stressful treatments: Holding with flock mates and Simulated shearing. The intermediate treatments could not be differentiated using change in ear canal temperature. Therefore, given the levels of statistical significance, our hypothesis that stressors of different intensities could be discriminated by changes in ear canal temperature was only partially supported. Reasons for the inability to discriminate between all treatments include a lack of sensitivity of change in ear canal temperature as an index of stress, high individual variability in responses to stress, and thermal sensor malfunction.

Comparison of two-stage selection breeding programmes for terminal sire sheep - Jopson NB; Amer PR; McEwan JC (Proceedings of the New Zealand Society of Animal Production, 2004)
Two-stage selection is a technique used in animal breeding to make the use of expensive measurements economically viable in a breeding programme. Selection candidates are first screened using inexpensive, but imperfect, predictors of their genetic merit. A selected subset are then evaluated using more accurate, but expensive, measurements and the final selection is made. This study compared the assessment of carcass composition traits using either computed tomography (CT) scanning or progeny testing (with 10 or 20 progeny per sire; PT10 and PT20, respectively) in the second stage of two stage selection systems using quantitative genetic theory. Stage 1 selection was assumed to be based on live weight and ultrasonic predictions of carcass merit. For a genetic correlation of 0.7 between ultrasonic and CT/PT measures, the economic return peaked for progeny test at $2.70 and $2.38 per commercial ewe when 10 and 5% of the male selection candidates were evaluated in PT10 and PT20, respectively. CT had a greater return at $3.52 per commercial ewe when 20% of the male selection candidates were evaluated using CT. The results show that given the moderate heritability of carcass composition traits, the reduction in generation interval and the lower cost of evaluation of CT outweighs the increased accuracy of selection and higher mating ratios associated with progeny testing.

Condensed tannins in birdsfoot trefoil (Lotus corniculatus) reduce methane emissions from dairy cows - Woodward SL; Waghorn GC; Laboyrie PG (Proceedings of the New Zealand Society of Animal Production, 2004)
Ruminant methane production contributes 34% of New Zealand greenhouse gases, but emissions are affected by feed type. A trial conducted at Dexcel measured methane production by 32 Friesian dairy cows grazing either good quality perennial ryegrass pasture or birdsfoot trefoil (lotus, Lotus corniculatus), a legume with high nutritive value that contains condensed tannins (CT; 2.62 g CT/100 g DM). Half the cows on each diet were drenched with polyethylene glycol (PEG) to inactivate the CT and allow the effect of CT on methane production to be determined. Total methane production, measured using the SF6 tracer technique, was similar for the lotus and ryegrass cows (343.2 vs 360.6 g CH4/cow/d; ns), however, methane production per unit DMI was lower from cows fed lotus (19.9 vs. 24.2 g CH4/kg DM, P<0.001). The CT in lotus reduced methane production by 13% relative to lotus when the CT had been inactivated by PEG, and was responsible for 66% of the difference between lotus and ryegrass. Cows fed lotus produced 32% less methane/kg milksolids compared to good quality ryegrass. The feasibility of feeding lotus as a methane mitigation option should now be assessed at a farm systems level to investigate effects on other greenhouse gases, productivity and profitability.

Dairy technology contract session - Anonymous (Proceedings of the New Zealand Society of Animal Production, 2004)
Currently, several very significant research projects are being undertaken in New Zealand that will impact the pastoral industry, and the dairy industry in particular, during the next ten years. This session highlights some of the technologies in the R&D pipeline, examines the impact these technologies will have on the industry, and explores what this means for the way scientists conduct animal production research. Professor John McRae, Deputy Director of Research at the Rowett Institute, UK, is the Landcorp Lecturer who opens the session by giving a world view of some of the new technologies and opportunities for pastoral industries. Undoubtedly one of the largest advances expected in the next ten years will be in animal genetics. John McEwan (AgResearch) describes the bovine genome project and what the project means for New Zealand, Richard Spelman (Livestock Improvement Corporation) provides an update on the search for bovine QTL, and Bill Montgomery (LIC) describes the future genetic progress of dairy cattle and the implications for the industry. Exciting progress is also being made in forage production. Dr Kieran Elborough (ViaLactia Biosciences) relates the advances being made in forage production and the implications for pastoral industries, and Ian Williams (Genetic Technologies, Pioneer) presents recent advances in maize hybrid technology. The session concludes with Stuart Gordon (LIC) describing customer focused technology, and John Caradus (Dexcel) presenting how these technologies may be integrated into future farm systems.

Dark fibre content of some New Zealand export wool consignments - Reid TC; Urquhart RA (Proceedings of the New Zealand Society of Animal Production, 2004)
Levels of dark fibre contamination were determined on 49 core samples of scoured wool, representing 30 export consignments of crossbred wool received from three exporting companies. The concentrations of dark fibres ranged from 0 to over 3300/kg. Only four consignments contained less than 100 dark fibres/kg, twelve contained less than 500/kg, while four contained more than 2000/kg. The two highest levels of contamination (>2300/kg) were found in consignments containing lambs wool, although other consignments with lambs wool contained relatively low levels (<500/kg). Some fleece blends also contained relatively high levels of contamination (>1000/kg). All consignments containing down fleece wool were contaminated with dark fibres to levels which were highly correlated with the proportions of down fleece wool. Overall, 53% (range 7-100%) of the dark fibres found were melanin pigmented, 14 % (range 4-33%) were urine stained and 25% (range 5-63%) were of foreign origin. The results indicate that there is a considerable degree of dark fibre contamination in some export consignments of New Zealand crossbred wool. The one single factor consistently associated with increased levels of contamination was the presence of down fleece wool in the blend. The presence of lambs wool was associated with high levels of contamination in some consignments, but not in others. This suggests that only some lines of lambs wool contain high levels of dark fibre contamination.

Decreased gene expression of integrins in epithelial cells during mammary engorgement - Singh K; Dobson J; Stelwagen K; Prosser CG; Farr VC; Molenaar A; Davis SR (Proceedings of the New Zealand Society of Animal Production, 2004)
In ruminants, the molecular mechanisms regulating mammary involution and apoptosis (programmed cell death) are not well characterised, but extensive research in rodents has established that many cell types, including mammary epithelial cells, require anchorage to the extracellular matrix for survival. This anchorage is mediated via the integrins, a family of transmembrane glycoproteins that bridge intra- and extracellular compartments enabling direct communication between adaptor molecules in the cytoplasm and specific receptor motifs on the ECM proteins (Clark & Brugge, 1995; Giancotti & Ruoslahti, 1999; Hynes, 1992). Integrins form heterodimers between α and β subunits to produce more than 20 different receptors, and many subtypes have been identified in mammary glands (Clark & Brugge, 1995). We have shown previously that one such integrin, β1, is reduced rapidly as a result of induced weaning in rodents, and these changes are followed by apoptosis (McMahon et al., 2004). The aim of this study was to investigate the molecular mechanisms that may regulate mammary involution in the bovine by examining cell-matrix interactions that may be involved in survival of mammary epithelial cells, ultimately to improve lactational persistency and tolerance of extended milking intervals ...

Economical analysis of year round lamb production - Morel PCH; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2004)
The traditional lamb production system in New Zealand is driven largely by the seasonal pattern of pasture growth and ewes lambing once a year. An alternative is the implementation of year-round lamb production systems such as the STAR system, where ewes lamb five times over a three-year period, thus providing a continuous supply of lambs. A modelling exercise was undertaken to assess the economic viability of the STAR system. The model simulates pasture growth and flock energy requirement on a daily basis over a three year period for both the traditional system and the STAR system and calculates gross margins. The model was run for a 100ha block using average Manawatu pasture growth rates. The two systems were set to consume 11000 kg DM/ha of pasture per year. The model indicates that, at the same lambing percentage (160%) the STAR system earned an extra 26% of income compared with the traditional system. Even at a lower lambing percentage (148 versus 160) the system can match a seasonal lamb production system. With a 10 % premium for out of season lambs the STAR system generates an extra 56% in profit.

Effect of dose of Streptococcus uberis infused into the mammary gland of lactating cows on clinical signs, bacterial count, somatic cell count and milk production - McDougall S; Parker K; Swift S; Harcourt S; Sutherland G (Proceedings of the New Zealand Society of Animal Production, 2004)
This study was to evaluate changes in cow productivity and milk value from feeding a rumen-protected form of CLA to pasture-fed dairy cows in early lactation. 30 New Zealand Friesian dairy cows were randomly assigned at calving to either 0g (control) or 120g/d of a commercial rumen protected feed containing CLA from 4 days post-calving for 16 weeks. Milk yield and composition data was collected weekly. A simulation model was used to calculate yield of dairy products based on accumulated yields of milk and its components per cow during the experimental period. Feeding CLA reduced (P<0.001) fat concentration (3.1% vs 4.2%) and increased (P<0.05) milk yield (2688 kg vs 2423 kg), and protein yield (89.9 kg vs 81.2 kg). The effect of CLA on milk fat concentration was reflected in the yield of dairy products and milk value. Milk from cows fed CLA had less (P<0.01) excess of fat sold as butter (48.4 vs 69.4 kg butter). The value of milk ($/kg MS) was higher (P<0.001) from cows fed CLA than from control cows at 2002/03 prices ($3.87 vs $3.66) and when butter price was low ($3.56 vs $3.24).

Effect of ergot alkaloids on liveweight gain and urine lysergol level in ewe hoggets and heifers - Layton DL; Fletcher LR; Litherland AJ; Scannell MG; Sprosen J; Hoogendoorn CJ; Lambert MG (Proceedings of the New Zealand Society of Animal Production, 2004)
Ingestion of ergot alkaloids can reduce live-weight gain (LWG) in sheep and cattle. The objective of this experiment was to determine if the enzyme-linked immunosorbent assay (ELISA) for urinary lysergol level provided an accurate measure of ergot alkaloid dietary intake. Forty hoggets and 60 heifers were fed ryegrass seed containing ergovaline (EV) (0.0 to 75.0 µg EV/kg LW hogget; 0.0 to 35.0 µg EV/kg LW heifer) daily. The feeding trial was repeated after 30 days for the hoggets. Urine lysergol:creatinine ratio increased linearly for hoggets from 1.91 to 5.80 (P<0.001) and LWG was linearly suppressed from 110 to 60 g/d (P<0.01) and 30 days later, from 35 to -130 g/d (P<0.05) for intakes of 0.0 to 75.0 µg EV/kg LW. Heifer urine lysergol:creatinine ratio increased linearly from 1.60 to 5.21 and LWG declined from 1.0 to 0.85 kg/d for intakes of 0.0 to 35.0 µg EV/kg LW (P<0.05). Urinary lysergol:creatinine ratio increased by 0.056 ± 0.007 (P<0.001, r2 = 0.67) in hoggets and by 0.082 ± 0.006 (P<0.001, r2 = 0.77) in heifers, for every 1 µg EV/kg LW consumed. These studies demonstrated a strong relationship between ergot alkaloid dietary intake and urine lysergol:creatinine ratio.

The effect of ewe and lamb post-parturient behaviour on lamb survival to weaning: A comparative study of Finns and Texels - Everett-Hincks JM; Stafford KJ; Blair HT; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2004)
Post parturient behaviours of twinning Finn and Texel ewes and their lambs were monitored under commercial conditions and a relationship sought between this and lamb survival to weaning. Texel lamb survival to weaning was greatest when Texel ewes quickly made contact with their lamb following birth (within 2 minutes) and for lambs that located their dam’s udder within 30 minutes from birth. Finn lamb survival to weaning was improved when Finn lambs were more vocal after birth, when Finn ewes had higher MBS and when Finn ewes spent a greater proportion of time grooming their lambs. Variation in perinatal behaviour within and across breeds was large and therefore potential exists for improving the ability of the ewe and lamb to bond successfully at parturition by selecting for some of the behaviours identified in this study that encourage lamb survival to weaning.

The effect of ewe nutrition on maternal behaviour score and litter survival - Everett-Hincks JM; Blair HT; Stafford KJ; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2004)
Mothering ability was investigated in two breeds of sheep with twin and triplet litters in 2000. The study was carried out on a commercial sheep farm with high reproductive rates gained through intensive selection in its Coopworth flock and the introduction of East Friesian genes by crossbreeding. East Friesian Coopworth (EFCoop) ewes maintained body condition between pregnancy scanning and lambing whereas Coopworth ewes lost body condition (-0.35 CS). Plasma β-hydroxybutyrate (β -OHB) was significantly higher in Coopworth ewes prior to lambing. Coopworth and EFCoop ewes with triplet litters had elevated levels of plasma â- hydroxybutyrate concentration compared to ewes with twins (0.70 ± 0.03 vs 0.49 ± 002, P<0.0001). Coopworth ewes had higher triplet litter survival rates to tagging (0.86 ± 0.03) compared with EFCoop ewes (0.68 ± 0.05) (P<0.001). The maternal behaviour score (MBS) of ewes was determined within 24 hours of birth on the basis of their response to the shepherd tagging their lambs on a 5-point scale from 1 (ewe leaves litter and does not return) to 5 (ewe remains within 1m of her litter). The maternal behaviour score (MBS) was higher in Coopworth ewes (3.6 ± 0.04) than the EFCoop ewes (3.4 ± 0.07) and increased with litter size but remained constant for EFCoop ewes regardless of litter size. The results of this study suggest that ewes that maintain condition in late pregnancy provide a more suitable maternal environment to support their litters. This is increasingly important for triplet litters. This study shows that a ewe that has slightly higher plasma β-hydroxybutyrate levels, is not as receptive to the demands of her litter and is sensitive to human interference as indicated by lower MBS.

The effect of grain supplementation on the faecal pH of horses maintained on pasture - Rogers CW; Eastwood B; Gee EK; Firth EC (Proceedings of the New Zealand Society of Animal Production, 2004)
The aim of this study was to investigate the effect of grain supplementation on the faecal pH of horses maintained at pasture. Data were obtained from twelve mixed age horses kept at pasture, six controls 530 ±9.4 kg and six carbohydrate supplemented 513 ±10.2 kg. The supplemented horses were each feed up to 6.15kg of crushed oats in two feeds (am and pm) per day over a 38 day period. The supplementation was divided into seven treatment periods; a four day period with no grain (block 1), six days with the addition of grain to the diet at a rate of +0.5kg per day (block 2), six days with 3.4kg per day (block 3), four days with the addition of 0.5kg oats per day (block 4), six days fed 6.16kg per day (block 5), six days decreasing grain fed (block 6) followed by a five day observation period with no grain fed (block 7). Faecal material was collected daily for analysis immediately after defecation during the am feeding time. Throughout the supplementation trial there were no significant differences between the supplemented and control groups. There was a significant effect of period on faecal pH (P<0.05). There was no interaction of treatment and period. There was a trend for faecal pH to decrease during the trial. Block 7 was significantly different to all other blocks. Block 5 was significantly different to Block 1 (P<0.01). Within the model horse was a significant effect (P<0.05). There was a strong correlation between the control and treatment groups for faecal pH throughout the trial (r2=0.86). There was a trend for increased rainfall in the 2nd half of the supplementation trial which was associated with increasing soil temperature (P<0.01). The lack of significant change in faecal pH with increased grain supplementation indicates that for pasture kept horses factors such as pasture intake and greater activity may have a role in buffering the negative effects of a high grain diet.

The effect of pre-calving and post-calving nutritional regimes on calf birth weight and pre-weaning growth - Morris CA; Smeaton DC; Pleasants AB (Proceedings of the New Zealand Society of Animal Production, 2004)
Numerous studies with New Zealand beef cattle have been carried out to determine responses of live weights or reproductive/survival traits to changes in the level of nutrition, at various stages during the annual production cycle. Various studies have also been carried out to describe how much of the variation for these traits of the cow or calf is genetic. This brief summary explores the possibility that some of these cattle data could be re-evaluated because of their possible relevance and analogies to current medical questions of interest.

Effect of precalving feeding level on the milk production of grazing dairy cows - Roche JR; Kay JK; Kolver ES; Aspin PW; Lee J; Sugar B; Napper AR (Proceedings of the New Zealand Society of Animal Production, 2004)
Fifty-two multiparous dairy cows were allocated to four treatments with an apparent daily intake of 5.8, 8.9, 10.0 or 11.2 kg dry matter (DM)/cow/day of pasture for 27±9.6 days precalving. This equated to 1.3, 2.0. 2.3 and 2.6% of liveweight (not including the conceptus weight; LW). Following calving, all cows were fed generously on pasture. Daily milk yields were recorded postcalving and fat, protein and lactose concentrations determined on 2 days each week for 5 weeks. Blood was sampled 17 days precalving, on the day of calving and on days 1, 2, 3, 4, 7, 14, 28 and 35 postcalving. Precalving plasma concentrations of insulin-like growth factor-1 (IGF-1) increased (P<0.05) quadratically with increasing pasture intake. Concentrations of growth hormone declined (P<0.05) linearly and concentrations of non- esterified fatty acids declined (P<0.001) quadratically with increasing DM intake. Plasma concentrations of these metabolites postcalving showed no effect of precalving feeding. Level of feeding precalving did not affect milk yield or the yield of fat, protein or lactose in milk, but postcalving DM intake was negatively (P<0.1) related to precalving DMI. These results indicate that 0.93 MJ metabolisable energy/kg LW0.75 was required in the final three weeks of gestation to maintain cow energy balance.

The effect of sward height during pregnancy on wool grown by ewes rearing twins or triplets - Sherlock RG; Torbatinejad N; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2004)
Previous work estimating the impact of rearing lambs on wool growth and processing characteristics has been done primarily with single and twin-bearing ewes. The effect of bearing/rearing triplets on wool growth has been largely extrapolated from these data. The aim of this study was to compare the wool growth and quality of twin- and triplet- bearing/rearing ewes offered different sward height allowances. After pregnancy scanning, 94 Romney ewes (including 68 twin- and 26 triplet-bearing ewes) with 6 weeks wool growth, were randomly allocated to four different sward heights (2, 4, 6 and 8 cm). Within the first 24 hours of parturition ewes were transferred to one of two sward heights (4 and 8 cm). Ewes were shorn 87 days after parturition, the fleece was weighed and a sample was taken from the midside for measurement of fleece characteristics. There were no interactions between nutritional treatment and litter size for any wool measurements. Fleeces from twin-bearing/rearing ewes tended to be heavier (P<0.1 ; 2.0 kg vs 1.9 kg) than those from triplet-bearing/rearing ewes. There was no effect of litter size on any other wool characteristic. Ewes offered 2 cm during the last half of pregnancy had lighter (1.6 vs 2.2 kg, P<0.05) and finer (39.0 vs 41.8 µm, P<0.05) fleeces than those offered 4 cm but there was no increase in weight or fineness for those offered more than 4 cm. Nutritional treatments post parturition had no significant effects on wool characteristics. There seems to be little benefit, in terms of wool growth and wool processing characteristics, of offering twin- or triplet-bearing ewes a sward height of more than 4 cm.

Effect of timing of insemination of dairy cows with liquid semen relative to the observation of oestrus - Vishwanath R; Melis J; Johnson DL; Xu ZZ (Proceedings of the New Zealand Society of Animal Production, 2004)
Many studies have confirmed that the best conception rates are obtained when cows are inseminated from mid to late oestrus. The conclusions of Trimberger, (1948) has led to the universally accepted AM - PM schedule for inseminating cows. The guideline suggests that cows found in oestrus during the AM period be inseminated at the following PM and the cows in oestrus at the PM be inseminated the following AM. Variations of this rule have been tested with single and multiple AI during oestrus periods and once daily AI after the AM milking with no adverse effect on conception rates. The objective of this study was to determine the effect of time of insemination on Non Return Rates (NRR’s) in a sample of seasonal breeding New Zealand dairy cows submitted for insemination once a day after following the AM - PM guideline. Two hundred farms participated in this trial with over 12,000 animals representing Friesian, Jersey and Cross breeds were included in this dataset. The farmers were asked to keep accurate records on when cows were first detected in oestrus during the first two weeks of mating. There was no significant difference in 18 to 24 day non return rates for all cows observed in heat at the two time periods and inseminated the following AM (71.8%, PM and 71.6% AM respectively, p = 0.18). There was no effect of bulls or age of cows. A nominal effect of breed of cow was observed. In conclusion, there was no effect on NRR when cows were inseminated at the one time period after AM milking whether they were first observed in heat the previous PM or the AM just prior to insemination.

The effect of weaning date, gastro-intestinal nematode challenge and nutrition on beef calf growth - Boom CJ; Sheath GW; Vlassoff A (Proceedings of the New Zealand Society of Animal Production, 2004)
Two experiments were conducted to understand the interactions between calf weaning date, level of nutrition and parasite challenge. In the first experiment, spring-born calves were weaned at 6 or 9 months of age (early or late weaning) and subject to natural parasite challenge, or natural plus an additional dose of 7500 infective larvae/day. Late weaned calves (with cows) also had either high or low pasture allowance treatments imposed. When calves were 9 months of age, calf liveweights (kg) were 253, 302 and 277 (SED 3.9) for the early wean/high nutrition, late wean/high nutrition and late wean/low nutrition treatments respectively and high and low nutrition cow liveweights were 494 and 479 kg (SED 4.8) respectively. At 9 months of age, early weaned calves showed higher faecal egg counts (P<0.05). Dosing with additional parasitic larvae had no effect on early weaned calves, but lowered late weaned calf weights. In the second experiment, calves were weaned at 6 months of age or left un-weaned until the age of 9 months when all calves were slaughtered. Un-weaned calves showed lower gastro-intestinal worm counts than early weaned calves. In both experiments, late weaned calves showed substantial liveweight advantage and lower parasite burdens. Reducing the nutrition of late weaned calves and cows reduced the size of this liveweight benefit. Later weaning is a management option for farmers seeking to reduce reliance on anthelmintic drenches without the associated production loss.

The effect on sheep reproduction of grazing willow fodder blocks during drought - Pitta DW; Barry TN; Lopez-Villalobos N; Kemp PD (Proceedings of the New Zealand Society of Animal Production, 2004)
A trial was conducted in the summer/autumn of 2003 to determine the effect of grazing on willow fodder blocks (6,000 stems/ha) during mating, relative to control ewes grazed on drought pasture, upon ewe production and reproduction. Grazing occurred over 10 weeks, from 19 February including 3 cycles of mating, with ewes randomly assigned to four treatment groups each of 100. The treatments were short drought pasture (typical of drought pasture), long drought pasture (typical of the pasture growing in the willow fodder blocks), short drought pasture with restricted willow access (restricted access) and full access to willow fodder blocks (fenced on the willow all the time; full access). After mating the four groups were joined together and managed as one mob until weaning. Substantial live weight loss occurred in the short control group (101 g/day), as would occur in severe drought conditions and reproductive rate was low. Ewes in the full access group had significantly (P<0.05) less live weight loss of 40g/day, with reproductive rate increased by approx 20% units (P<0.05). The increase in reproductive rate in the group with full access to willow fodder blocks was due to increases in fecundity, with more ewes giving birth to twin lambs. Live weight loss during mating in the long control and restricted access groups was intermediate between the short control and full access groups (75-86 g/d) and significantly different from either (P<0.05); reproductive rate was also intermediate between the short control and full access groups but was not significantly different from either (P>0.05). Grazing willow fodder blocks with full access during times of drought can be used to reduce the decline in reproductive rate, which occurs when ewes are mated on drought pastures.

Effects of a commercial feed containing conjugated linoleic acid on the production of milk components and the value of milk - Back PJ; Lopez-Villalobos N (Proceedings of the New Zealand Society of Animal Production, 2004)
This study was to evaluate changes in cow productivity and milk value from feeding a rumen-protected form of CLA to pasture-fed dairy cows in early lactation. 30 New Zealand Friesian dairy cows were randomly assigned at calving to either 0g (control) or 120g/d of a commercial rumen protected feed containing CLA from 4 days post-calving for 16 weeks. Milk yield and composition data was collected weekly. A simulation model was used to calculate yield of dairy products based on accumulated yields of milk and its components per cow during the experimental period. Feeding CLA reduced (P<0.001) fat concentration (3.1% vs 4.2%) and increased (P<0.05) milk yield (2688 kg vs 2423 kg), and protein yield (89.9 kg vs 81.2 kg). The effect of CLA on milk fat concentration was reflected in the yield of dairy products and milk value. Milk from cows fed CLA had less (P<0.01) excess of fat sold as butter (48.4 vs 69.4 kg butter). The value of milk ($/kg MS) was higher (P<0.001) from cows fed CLA than from control cows at 2002/03 prices ($3.87 vs $3.66) and when butter price was low ($3.56 vs $3.24).

Efficacy of pre-mating supplementation with mono propylene glycol on reproductive performance of cows in commercial dairy herds - Tunon GE; Taufa VK; Burke CR; Holmes CW; Chagas LM (Proceedings of the New Zealand Society of Animal Production, 2004)
Prolonged postpartum anoestrous intervals (PPAI) are the major source of infertility in New Zealand dairy cows. Postpartum supplementation with mono propylene glycol (MPG) was previously shown to reduce PPAI in heifers. The present experiment tested this treatment in four large commercial dairy herds. During the six-week period preceding the planned start of mating (PSM; week 0), cows were drenched either once (1xMPG) or twice (2xMPG) daily with 200 ml MPG, or served as untreated controls (CON). Analyses were confined to the group of cows that were anoestrus at Week –6 or calved between Week –6 and Week –4 relative to PSM (n = 662 to 669 per treatment). Change in body condition score between Week –6 and Week –1(∆BCS), and proportion of cows that were anoestrus at Week –1 were influenced by herd, age and time of calving (P<0.05) but not by treatment (P>0.1). Treatment did not influence the proportion of anoestrous-treated cows inseminated after oestrus detection (n =263), or the pregnancy rate among all cows. Pre-mating supplementation with MPG did not influence ∆BCS, the percentage of cows that were anoestrus at Week –1, or rates of submission and conception. Change in BCS affected both milk yield and pregnancy rates, where cows that gained BCS produced less milk but showed higher 6-week pregnancy rates. This study highlighted that key factors influencing the percentage of anoestrus at PSM are cow age, time of calving and management of the herd.

Embryo transfer for improved feed conversion efficiency in cattle - Smeaton DC; Scott ML; Webby RW; McGowan L; Cameron C; Brooky A (Proceedings of the New Zealand Society of Animal Production, 2004)
Two experiments were conducted to understand the interactions between calf weaning date, level of nutrition and parasite challenge. In the first experiment, spring-born calves were weaned at 6 or 9 months of age (early or late weaning) and subject to natural parasite challenge, or natural plus an additional dose of 7500 infective larvae/day. Late weaned calves (with cows) also had either high or low pasture allowance treatments imposed. When calves were 9 months of age, calf liveweights (kg) were 253, 302 and 277 (SED 3.9) for the early wean/high nutrition, late wean/high nutrition and late wean/low nutrition treatments respectively and high and low nutrition cow liveweights were 494 and 479 kg (SED 4.8) respectively. At 9 months of age, early weaned calves showed higher faecal egg counts (P<0.05). Dosing with additional parasitic larvae had no effect on early weaned calves, but lowered late weaned calf weights. In the second experiment, calves were weaned at 6 months of age or left un-weaned until the age of 9 months when all calves were slaughtered. Un-weaned calves showed lower gastro-intestinal worm counts than early weaned calves. In both experiments, late weaned calves showed substantial liveweight advantage and lower parasite burdens. Reducing the nutrition of late weaned calves and cows reduced the size of this liveweight benefit. Later weaning is a management option for farmers seeking to reduce reliance on anthelmintic drenches without the associated production loss.

Expression of the tight junction protein zonula occludens-1 during mammary engorgement - Cooper CV; Stelwagen K; Singh K; Farr VC; Prosser CG; Davis SR (Proceedings of the New Zealand Society of Animal Production, 2004)
An increase in tight junction (TJ) permeability occurs during extended milking intervals and is associated with reduced milk secretion. This paper examines temporal changes in the expression of a major TJ protein, zonula occludens-1 (ZO-1), during mammary engorgement. Alveolar mammary tissue was collected from 52 mid-lactation dairy heifers at 0, 6, 12, 18, 24, 36 and 72 h, and at 8 d following abrupt cessation of milking (n ≥ 6 cows per time point). ZO-1 protein expression significantly decreased during mammary engorgement (P<0.05). Similarly, ZO-1 mRNA expression had halved by 36 h to 8 d post-milking (P<0.05). In a second trial, alveolar tissue was collected from the udder halves of late-lactation dairy cows (n = 4) that were milked unilaterally, either once-daily or twice-daily for 4 days. A 1.7-fold increase in ZO-1 mRNA expression was detected after once-daily milking, compared with twice-daily milking (P<0.05). The down-regulation of ZO-1 during mammary engorgement is consistent with increased TJ permeability. However, the up-regulation of ZO-1 mRNA expression during short-term once-daily milking suggests that TJ function is repaired as the mammary gland adjusts to the extended milking interval. In conclusion, we have identified changes in ZO-1 critical to TJ function in bovine mammary glands.

Factors affecting non-return rate in dairy cattle - Johnson DL (Proceedings of the New Zealand Society of Animal Production, 2004)
Non-return rate (NRR) to artificial insemination (AI) gives a measure of bull fertility early in the mating season. Calving rate can be biased due to culling and is available too late in the season to be useful for detecting sub-fertile bulls. A current limitation, in the New Zealand dairy industry, to calculating the NRR for bulls is that it is largely based on raw averages of binary data (returned or not) and using only qualifying matings. For example, for an 18-24 day NRR, a mating would qualify if the insemination occurred at least 24 days prior to the end of the observation period and this would utilise only about 42% of the available mating information. Currently no account is taken of environmental factors that may affect NRR (e.g. region, breed of cow) and of the number of inseminations for each bull. The variable of interest is the time interval between the mating date for a cow and an end-point. For a cow returning to service during the AI mating period, the end-point is the date of return to service. For non-returns within the mating period, the end-point is the final AI mating date for the herd. The former type of mating record is uncensored while the latter is a censored record in the sense that a possible return event may not be observed.

Factors associated with calving difficulty in embryo transfer mated cattle - Smeaton DC; Scott ML; Webby RW; Cameron C; McGowan L; Brooky A (Proceedings of the New Zealand Society of Animal Production, 2004)
Data were collected from 249 cows over 2 years at Whatawhata Research Centre on pelvic area, weight and breed of embryo transfer mated cow, calf birth weight, breed and a defined calving difficulty score. Cow liveweight and pelvic area were significantly correlated (R2 = 0.56, P< 0.05), but cow liveweight and calf birth weight were not (R2 = 0.07, NS). Cow pelvic area and calf birth weight were also not related (R2 = 0.04, NS). In July of each year, the Jersey cows were 119 kg lighter (P<0.001), had a smaller pelvic area (264 vs. 322 cm2, P<0.001) and more calving difficulties (26 vs. 5%, P<0.001) than Hereford x Friesian (HxF) cows. Across breeds, pelvic area (P<0.01) and cow liveweight (P<0.001), when fitted individually, were negatively associated with the probability of a cow having an assisted calving. On its own, the impact of calf birth weight was NS, although it explained additional variation (P<0.05) if cow liveweight was in the model. Within the range of calf breeds (NS) we used, we predict that any of recipient breed, cow liveweight or pelvic area (in decreasing order of reliability) could be used to reject cows at ET that might cause problems at calving although errors of estimation will result in wasteful rejection of cows and will not eliminate calving problems.

Fetal programming of postnatal phenotype and obesity - experimental evidence from biomedical research - Krechowec SO; Vickers MH; Breier BH (Proceedings of the New Zealand Society of Animal Production, 2004)
The evidence for the fetal origins of adult disease (diabetes, cardiovascular) is reviewed. There is evidence of a disturbed endocrine communication between the hypothalamus, adipose tissue and the endocrine pancreas in the pathogenesis of programming-induced obesity. Hypercaloric nutrition during postnatal life greatly amplifies prenatal effects on metabolic abnormalities, obesity, overeating and diminished exercise behaviour. Fetal programming research offers a novel approach to investigate the mechanistic basis of metabolic disorders.

Flystrike in lambs selected for resistance or susceptibility to ryegrass staggers, when challenged with high or low endophyte pastures - Young SR; Scobie DR; Morris CA; Amyes NC (Proceedings of the New Zealand Society of Animal Production, 2004)
Research has shown that incidence of flystrike is reduced in sheep grazing low endophyte ryegrass. This experiment was designed to test the hypothesis that where lambs are bred specifically for resistance to ryegrass staggers (RGS), their susceptibility to flystrike on the body should be correspondingly low, even when challenged with high levels of endophyte. Ewe and ram lambs were sourced from two lines, one selected for resistance (n = 85) and the other for susceptibility (n = 143) to ryegrass staggers. A further group of lambs (n = 63) produced by intercrossing the two lines was included. The lambs were run in 2 mobs, on high and low endophyte pasture, and monitored daily for signs of flystrike on the body. During the course of the experiment, susceptible (n = 34) and resistant (n = 1) lambs suffering from clinical ryegrass staggers had to be removed from the high endophyte pasture. These were excluded from the analysis. Ram lambs made up the majority of animals removed. Only ram lambs were flystruck on the body, particularly around the scrotal area. Significantly more resistant ram lambs (7 of 49) were flystruck than susceptible (3 of 85) or intercross ram lambs (2 of 27), regardless of pasture endophyte level (P < 0.1). More lambs (P < 0.1) were flystruck grazing ryegrass with high endophyte (n = 9) than low endophyte (n = 3). The only lambs flystruck while grazing non-endophyte pasture were RGS resistant rams. In contrast to the hypothesis, this experiment indicates that selection of animals for resistance to RGS may exacerbate their susceptibility to flystrike. The evidence presented here supports the literature that sheep grazing high endophyte pasture are more susceptible to flystrike. The question for farmers is whether their selection priority should be for pasture with resistance to insect pests, or for stock with resistance to RGS, or both.

Formation and excretion of phenol flavour compounds in sheep - Fraser K; Lane GA; Schreurs NM; Tavendale MH; Keogh RG; Kirk MR; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2004)
Rumen, plasma and urinary concentration of the undesirable phenol flavour compound 4-methylphenol was measured in two rumen-fistulated Romney wethers fed perennial ryegrass. Following a one week adaptation period, samples were collected at ca. 1 hr intervals after feeding on two sampling days one week apart. Maximal concentration of 4-methylphenol in the rumen, blood and urine was reached at ca. 2, 3, and 4.5 hr respectively, declining to a minimal concentration by 9 hr (15% of maximum), 11 hr (16%), and 18 hr (<1%) respectively. Thus phenol compounds formed in the rumen are cleared rapidly and efficiently by excretion into the urine. In a separate trial the absorption and excretion of the exogenous phenol, thymol, was measured. Four groups of 4 lambs grazed on pasture were dosed daily with either a control or 3 different levels of thyme slurry for two weeks. After one week of dosing spot urine samples were collected on two consecutive days. Upon completion of the two week dosing period the animals were slaughtered and subcutaneous fat samples collected. The concentration of thymol (conjugates) in the urine was highly correlated with the thyme dosage (r=0.848, P<0.001), but there was no significant correlation between dose level and the concentration of (free) thymol in the fat. These results suggest that the concentration of phenol flavour compounds in ruminant products is affected by the efficiency of conjugation and excretion as much as by their formation in the rumen.

Friesian Jersey crossbred trial: Generating phenotypes for the discovery of quantitative trait loci - Spelman RJ; Hooper JD; Stanley G; Kayis SA; Harcourt S (Proceedings of the New Zealand Society of Animal Production, 2004)
The breeding of improved varieties of agriculturally important species requires constant effort and innovation. The ways we in New Zealand use emerging technologies to maintain our low-cost, low-input, sustainable, pastoral agricultural systems are extremely important. When it comes to developing elite varieties and strains of ryegrass we have been, until very recently, disrupting much to achieve little: we rely on chance to find the right combinations of traits in our breeding lineages, whether animal germplasm or plants cultivars. The use of CisgenicsÆ, where heritable material is moved only within a species by either traditional or modern biotechnological means offers a better way for ryegrass breeding in line with a key principle of science and economics.

Fumarate reduces methane production from pasture fermented in continuous culture - Kolver ES; Aspin PW; Jarvis GN; Elborough KM; Roche JR (Proceedings of the New Zealand Society of Animal Production, 2004)
This experiment tested the hypothesis that addition of an organic acid (fumarate) would increase the energy captured from a pasture diet during ruminal fermentation. Pasture was fermented with 0, 10, 20, or 30 mM of fumarate constantly infused into four dual-flow continuous culture fermenters. Digestion characteristics responded linearly (P<0.05) as fumarate increased from 0 to 30 mM. Increasing fumarate from 0 to 30 mM reduced (P=0.057) methane production by 38%, and reduced the ratio of acetate:propionate (2.4 v.s. 1.5). Concentrations of propionate and total volatile fatty acids increased by 74% and 19%, respectively. These results were consistent with fumarate acting as an electron-accepting intermediary in the succinate-propionate pathway. The addition of fumarate increased energy capture from a pasture diet by improving the supply of glucogenic compounds and reducing losses to methane emissions.

Future genetic progress of dairy cattle in New Zealand - Montgomerie WA (Proceedings of the New Zealand Society of Animal Production, 2004)
Significant lifts in profitability have been achieved by New Zealand dairy farmers through the inclusion of increasing amounts of maize silage into a pasture based system. Most of this maize is grown off the dairy unit on farmer owned or leased runoff blocks or by contract growers. While there is still significant scope to improve dairy farm productivity by increasing maize silage input levels, there is considerable opportunity to also improve dairy farm productivity by reducing feed costs through improving maize silage yields, increasing milk output by lifting maize silage nutritional quality and improving agronomic stability of maize silage offering higher yields over a wider environmental range. Traditional plant breeding, genetic engineering and advances in agronomic management all have the potential to impact production potential and profitability of maize silage in New Zealand dairy farm systems.

Genetic and phenotypic relationships between milk protein percentage, reproductive performance and body condition score in New Zealand dairy cattle - Harris BL; Pryce JE (Proceedings of the New Zealand Society of Animal Production, 2004)
Recent research from the Australian In-Calf and New Zealand Monitoring Fertility projects have demonstrated that low milk protein percentage in early lactation is phenotypically linked to poor reproductive performance. The purpose of this study was to quantify the phenotypic and genetic relationship between body condition score (BCS), protein percentage (and other milk production traits) and the reproductive measures used to predict the female fertility breeding value in New Zealand’s Animal Evaluation System: probability of mating in the first 21 days of a herd’s mating period (PM21) and the probability of having a calf born to AI (CAI). Data on 99,870 first lactation cows, recorded as part of Livestock Improvement’s and Ambreed’s progeny test schemes were used for both a phenotypic analysis and to estimate genetic parameters. Effects of breed, heterosis, BCS, protein percentage and dairy conformation were statistically significant in logistic regression analyses on both CAI and PM21. Genetic correlations between protein percentage and PM21 and CAI were 0.18 and 0.20 respectively and genetic correlations of BCS and PM21 and CAI were 0.48 and 0.38 respectively. These results show that selection for protein percentage is unlikely to have a large effect on reproductive performance, while BCS is a promising tool to aid in selection for improved fertility.

Gross margin analyses of using cloned embryos in cattle - Smeaton DC; Woodward SJR; Wells DN; Smith JF (Proceedings of the New Zealand Society of Animal Production, 2004)
A spreadsheet model was developed that evaluated the gross margin (GM) profitability of clone embryos placed by embryo transfer into recipient cows compared to Hereford x Friesian cows naturally mated to a high growth rate finishing sire. Biological parameters in the model included variables of performance such as losses at various points through pregnancy, calving and rearing and cow losses and calving difficulty. Variance (SD) and correlation information associated with gestation length, birth weight and calf liveweight gain were included. Allowance was made for the extra costs associated with clone ET and the possibility of lower pregnancy rates. To provide a stable result, the model was based on a 1000-cow herd. Assuming 50% of clone ET cows are diagnosed pregnant at 28 days after ET (35 days of gestation) we determined that clone embryos must sell for NZ$84 each to break even with the natural mating system, assuming 80% of clones surviving to weaning would sell in niche markets at 3 times the price/kg liveweight of their cohorts. When all clones attracted the premium, the breakeven price was $142/embryo. The coefficient of variation (CV) of GM profit was 6% for the clone herd vs. 2% for the naturally mated herd. For smaller herds (say 100 cows), with a proportionately lower herd GM, the CV of GM and therefore risk, was higher, at 17%. At weaner clone premiums ranging from 2.25 to 4 times the normal weaner price/kg, the breakeven price ranged from $0 to $195/embryo respectively if 80% of the clones received the premium and $10 to $280 when all weaned clones received the premium.

Growth and development contract session - Pleasants AB (Proceedings of the New Zealand Society of Animal Production, 2004)
In 2003 the Centre of Research Excellence (CoRE) for Growth and Development was formed. The purpose is to conduct research into growth and development, focussing particularly on the issues of pre- and post-natal growth and its implications for human health. The medical challenges for the developed world are those associated with the nutritional environment, obesity and the associated illnesses of diabetes and cardio-vascular disease. There is evidence linking the propensity for these diseases to the nutritional status of the fetus in the first trimester of pregnancy and the interaction of this status with nutrition in the immediate post-natal period. In this respect the problem differs from the issues considered by animal production. Here the last trimester of pregnancy has received the most attention, and few domestic animals live long enough for cardio-vascular problems to arise. Nevertheless the skills and methods of investigation developed by animal scientists can be applied to these new problems. Animal production research and medical science have much to offer each other, but with a few notable exceptions this potential has not been realised. A cursory look at the references listed by the authors in this contract shows little evidence of contact. One of the goals of the CoRE is to promote this interaction. This contract session with the New Zealand Society of Animal Production has two goals. First, to make animal scientists aware of the questions facing medical scientists with respect to early growth and development, the focus of the CoRE effort. Second, to encourage individuals to make contact and build future networks with the aim of developing joint projects.

Heritability of puberty traits in dairy heifers in commercial herds - Morris CA; Hickey SM (Proceedings of the New Zealand Society of Animal Production, 2004)
Age and weight at puberty (first behavioural oestrus) are known to be heritable traits in experimental beef and dairy cattle. The recording required is usually labour-intensive, and may also be expensive if serial blood samples are taken to estimate progesterone concentrations. Our objective in this study was to ascertain whether a less labour- intensive approach for estimating age at puberty (AP) would still provide enough statistical power to show genetic variation among sire groups of Friesian and Jersey heifers grazing in large groups. Commercial heifers (n = 797) were born in the late winter/early spring of 2002, and were predominantly the result of artificial insemination (AI) matings. They were reared to weaning in six herds, and then grazed in five herds through 2003. Tailpaint was applied to heifers at visits to the grazing herds at 4-6 week intervals, and tailpaint loss was recorded at each visit to determine approximate date at puberty. Birth dates were known, and hence AP was calculated. The heritability of yearling live weight (W12) was used as a control measure. From four of the herds (n = 453), there were animals by 13 widely-used AI sires (9 Friesian and 4 Jersey), and 10 other sire groups were represented with at least 5 daughters each. The phenotypic standard deviations for AP and WP were 48 days and 34 kg, similar to that found in New Zealand experimental beef cattle herds. The pooled within-breed heritability estimates for AP, WP and W12 were 0.09 ± 0.10, 0.21 ± 0.14 and 0.24 ± 0.15, respectively. Confounding of AI sire group with date of birth of heifer was encountered. The breeding-value difference in AP between the top 7 and bottom 6 of the widely used AI sires was 15 days, or 1.05 genetic standard deviations. In conclusion, recording AI calves in large grazing herds may be a practical method of getting access to puberty data, but more frequent visits to each herd would probably be needed to reduce the noise, and increase the heritability for AP and WP.

Hogget mating in New Zealand - a survey - Kenyon PR; Morris ST; Perkins NR; West DM (Proceedings of the New Zealand Society of Animal Production, 2004)
Currently less than 30% of all hoggets are presented for mating in New Zealand. This would suggest that there are a number of disadvantages to this management practise. However to date it has not been accurately established what farmers perceive as the disadvantages of hogget mating and the relative importance of each of these disadvantages. A questionnaire was sent to New Zealand sheep farmers which asked a series of questions regarding farm type, size, farm class, flock type, flock size and the intended use of hogget mating in 2002 and its use in the past. Those farmers who were not intending to mate hoggets in 2002 were also asked to indicate the importance, on a scale of 1.4, of 11 stated reasons for not hogget mating. A total of 1981 questionnaires were returned and used in the present study from a total of 14,000 sent to farmers. Descriptive analysis indicated negative effects on two-tooth performance and lack of additional feed were the two main reasons for not mating hoggets. The least important variables were lack of experience and the need for extra rams/teasers. The intended use of hogget mating differed based on farm class, farm size, ewe flock size and farm and flock type. Farmers were more than twice as likely to mate hoggets in 2002 if they had a mixed-bred flock in comparison to a straight-bred flock and more than twenty times more likely to mate hoggets in 2002 if they had mated hoggets in previous years. This study indicates that farmers perceive impaired two-tooth performance as a major reason for not hogget mating, even though research to date would indicate this is not that case. Therefore either improved technology transfer is required or the effects of hogget mating on two-tooth performance need to be re-visited.

Ill-thrift in young growing cattle and sheep - Litherland AJ; Layton DL; Boom CJ; Knight TL; Hyslop M; Lambert MG; Cook TL (Proceedings of the New Zealand Society of Animal Production, 2004)
A questionnaire survey was designed to gauge consumer interest in goat meat. The questionnaire was responded to by 98 households living in or near Tokyo. The main results of the survey are as follows. 1) Impression of goat meat; 61% of the respondents indicated that goat meat was ìnot common in their homeî. 2) Consumer experience; only 16% of the respondents had experience of eating goat meat and they felt goat meat is ìsmellyî(50%), ìtenderî(38%) and ìdeliciousî(31%). 3) The two main reasons why consumers have not eaten goat meat were ìlack of purchasing opportunityî(78%) and ìdonít feel like eating itî(18%). 4) Options to promote goat meat consumption; 52% of respondents who have not eaten goat meat were prepared to purchase if it was available in the supermarket at a reasonable price and if recipes were added with the meat package. 5) Reasons for people not purchasing goat meat included ìdislike of new meatî and ìpity for the goatî. These results show that goat meat can be promoted to the Japanese households as ìa new productî if the price is reasonable and recipes are added to the package. However, a considerable number of market strategies need to be implemented to achieve the acceptance of goat meat by Japanese consumers.

Influence of feeding level after drying off on incidence of mastitis and keratin plug formation in dairy cows - Summers EL; Lacy-Hulbert SJ; Williamson JH; Sugar BP (Proceedings of the New Zealand Society of Animal Production, 2004)
Prolonged postpartum anoestrous intervals (PPAI) are the major source of infertility in New Zealand dairy cows. Postpartum supplementation with mono propylene glycol (MPG) was previously shown to reduce PPAI in heifers. The present experiment tested this treatment in four large commercial dairy herds. During the six-week period preceding the planned start of mating (PSM; week 0), cows were drenched either once (1xMPG) or twice (2xMPG) daily with 200 ml MPG, or served as untreated controls (CON). Analyses were confined to the group of cows that were anoestrus at Week ñ 6 or calved between Week ñ 6 and Week -4 relative to PSM (n = 662 to 669 per treatment). Change in body condition score between Week ñ 6 and Week - 1(∆BCS), and proportion of cows that were anoestrus at Week ñ1 were influenced by herd, age and time of calving (P<0.05) but not by treatment (P>0.1). Treatment did not influence the proportion of anoestrous-treated cows inseminated after oestrus detection (n =263), or the pregnancy rate among all cows. Pre-mating supplementation with MPG did not influence ∆BCS, the percentage of cows that were anoestrus at Week ñ1, or rates of submission and conception. Change in BCS affected both milk yield and pregnancy rates, where cows that gained BCS produced less milk but showed higher 6-week pregnancy rates. This study highlighted that key factors influencing the percentage of anoestrus at PSM are cow age, time of calving and management of the herd.

Influence of material and sire effects on antibody response following clostridial vaccination of Friesian-Jersey crossbred calves - Harcourt SJ; Buddle BM; Hamel K; McNaughton LR; Spelman RJ (Proceedings of the New Zealand Society of Animal Production, 2004)
As part of an ongoing project to identify quantitative trait loci (QTL) for economically important traits in New Zealand dairy cows, a vaccine trial was conducted to measure the antibody response of 10 week old Friesian-Jersey crossbred calves to two antigenic compounds of a clostridial vaccine (Clostridium novyi B and Clostridium tetani toxoids). Blood samples were collected from 469 calves prior to vaccination at 10 weeks of age, prior to re-vaccination at 13 weeks of age and at 16 and 22 weeks of age. ELISA assays using conjugated rabbit anti-bovine IgG were conducted for both toxoids. Correlations and explanatory variables were calculated using correlation and general linear model (GLM) procedures in SAS. Antibody response to both toxins were relatively low after the first vaccination (week 13), but were boosted to high levels after revaccination (week 16). GLM analysis revealed a moderate sire effect contributing to the variability seen in the 13 week test against C. tetani (P=0.001) and the 16 week test against C. novyi (P=0.01). This variation in individual antibody response will be used in future research to identify genetic factors controlling the acquisition of immunity.

Justifying the appropriate length for docking lambs' tails - a review of the literature - Fisher MW; Gregory NG; Kent JE; Scobie DR; Mellor DJ; Pollard JC (Proceedings of the New Zealand Society of Animal Production, 2004)
It is generally accepted that tail docking is beneficial in farming systems where sheep are predisposed to dag formation and flystrike, but that it is a stressful procedure. Although there have been many studies of tail docking, relatively few have looked at the effects of different tail lengths. The incidence of flystrike depended on tail length, being least in medium-, and greatest in short-tail docked sheep. Short-tail docked ewes had higher rates of carcinoma of the vulva and short-tail docked lambs had a greater incidence of rectal prolapse. In some cases, increased tail length was associated with increased dags, and with longer tails crutching and shearing effort was greater. There apparently have been no studies documenting the effects of docking at different lengths on the welfare of the lamb at the time of docking, on muscle anatomy, or on defecation and urination. Furthermore, the results obtained in some studies were confounded by differences in breed (e.g. Merino) and mutilations (e.g. mulesing), which question the validity of extrapolating their conclusions to New Zealand conditions.

Landcorp Farming Lecture : Nutritional opportunities for longer-term, sustainable, ruminant production - MacRae JC (Proceedings of the New Zealand Society of Animal Production, 2004)
In the present era of ‘sustainability’ our ability to deliver longer-term, environmentally-friendly ruminant production systems, based on forage feeding with only limited (strategic) use of concentrates, might well depend on the ability of animal scientists to embrace multi-disciplinary approaches that can capitalise on the power of the modern technologies. Whilst environmental issues tend to dominate present thinking on sustainable systems, the longer-term viability of these systems may depend on economic aspects such as an ability to improve the efficiency of converting forage protein into animal product and an ability to sell these products to the health-conscious consumer. Communication between animal and plant scientists has already led to encouraging reports from collaborations in which forage breeders, utilising genomics-based marker-assisted selection techniques, have developed forages with higher water-soluble carbohydrate content which can promote increased milk production in dairy cows and live weight gain in lambs and beef steers. Similar communications between animal and biomedical scientists may provide opportunities for enhancing the ‘healthy-eating’ image of ruminant products. Several examples (e.g. n-3 polyunsaturated fatty acids, conjugated linoleic acids, selenium, specific milk proteins and the protein-linked delivery of calcium and phosphorus in milk and iron in meat) are used to indicate how current knowledge on the relationships between nutrient intake and the development of non-communicable diseases such as heart disease and cancer might be badged to help promote animal products as ‘healthy eating’ options.

Is lithium a candidate to modify rutting behaviour in stags? - Prouting MF; Nicol AM; Keeley MJ (Proceedings of the New Zealand Society of Animal Production, 2004)
Preliminary experiments assessed the potential of lithium to moderate the effects of the rut. Young (5-9 month old) stags were used to determine the kinetics of lithium in deer, establish appropriate dose rates, evaluate the opportunity for self-medication and to test whether behaviour would be modified. The relationship between lithium dose rate and plasma lithium concentration was established from acute administration (5 dose rates, 2 animals per dose) and confirmed with continuous medication for 31 days. A daily dose of 0.6 mmol Li/kg W (as LiCl) achieved a mean plasma Li concentration of (0.78 ± 0.04 mmol/l), which was within the therapeutic range (0.5–1.5 mmol/l). This daily dose, offered in drinking water (11.2 mmol Li/l as LiCl) to a group of (n=10) young stags induced a decline in both water (14%) and feed (12%) intake which was almost recovered after 4 weeks of self-medication. Liveweight gain averaged 252 ± 27 g/d for +Li animals compared with 263 ± 21 g/d for the -Li group (NS). Lithium treated stags moved more freely through a maze than did -Li stags, with 60% of the animals completing the maze compared with only 10% of the -Li group. There was no significant difference in the behaviour of +Li and -Li groups to the introduction of a unfamiliar stag or in their response to human handling. This work lays the foundation for studies on the potential for lithium therapy to modify the rut in adult stags.

Manipulating lamb birth weight and survival rate in singletons born to hoggets - Kenyon PR; Morris ST; West DM; Stafford KJ; Corner RA; Ottema K; Burnham DL (Proceedings of the New Zealand Society of Animal Production, 2004)
Lambs born to hoggets tend to be relatively lightweight at birth (Drymundsson, 1973; McMillan & McDonald, 1983) and display low survival rates to weaning (McCall & Hight 1981; McMillan & McDonald, 1983). In addition the incidence of singletons in hoggets often exceeds 92% (McCall & Hight, 1981; McMillan & McDonald, 1983). Therefore management procedures that improve both birth weight and survival of singleton lambs should have a significant effect on returns. Severe under nutrition during pregnancy of mature ewes can lead to reduced ewe and lamb performance (Rattray 1986), which can negatively affect lamb survival. However to date minimal research under New Zealand’s pastoral conditions has been undertaken in hoggets. In contrast to the mature ewe, it is also advantageous for the hogget to be increasing in conceptus-free live weight during pregnancy if lifetime performance is not to be negatively affected. Interestingly, under concentrate feeding regimes in the United Kingdom it has been reported that a high level of hogget nutrition in pregnancy, actually reduces both lamb birth weight and survival (Wallace et al., 1996). Shearing mature ewes in mid- to late-pregnancy has been shown to differentially increase singleton- (Morris et al., 2000; Kenyon et al., 2002a) and twin-lamb birth weights (Morris & McCutcheon, 1997; Morris et al., 1999; Kenyon et al., 2002b). Mid-pregnancy shearing has tended to increase twin-lamb survival rates (Morris et al., 1999; Kenyon et al., 2002b) but has been found to decrease singleton survival rates in one of four studies (Kenyon 2002). The effect of mid- to late-pregnancy shearing of hoggets has not been examined under pastoral conditions in New Zealand. Due to the low rate of twin pregnancies in hogget’s the chance of achieving a positive affect from mid-pregnancy shearing on both a lamb birth weight and survival may be low. The aims of these studies were to determine if hogget live weight change and shearing treatment during pregnancy could be used to manipulate singleton lamb birth weight and survival.

Mate selection to control inbreeding and maximise farm profit of commercial dairy cattle - Lopez-Villalobos N; Harris BL; Pryce JE (Proceedings of the New Zealand Society of Animal Production, 2004)
The objective of this study was to demonstrate the potential benefits of computerised mate selection in a commercial crossbred dairy herd of 411 cows mated to 10 Holstein-Friesian and 10 Jersey bulls. Mate selection was carried out using an evolutionary algorithm to perform single- or multiple-objective optimisation to maximise farm profit ($/4.5 t DM) and/or minimise inbreeding level of progeny. Restrictions were placed on the total number of mating pairs, the maximum number of matings per bull and per cow. Selection and mate allocation of bulls and cows at random produced progeny with average farm profit of $94 and inbreeding level of 1.70%. Mate selection applied to maximise farm profit yielded a mating set with an average farm profit of $181 and inbreeding level of 2.07%. Mate selection applied to minimise inbreeding level selected a mating set with average farm profit of $65 and inbreeding level of 0.03%. Mate selection applied to optimise farm profit and minimise level of inbreeding with a weighted ratio of 1:1, resulted in a mating set with average farm profit of $176 and inbreeding level of 0.44%. The results demonstrate that in the short term, inbreeding can be controlled at the same time as maximising farm profit using a computerised mating selection program with multiple-objective optimisation.

Measuring short periods of wool fibre growth using radiolabelling - Scobie DR (Proceedings of the New Zealand Society of Animal Production, 2004)
Brief periods cannot be measured with traditional autoradiographic methods on wool fibres because the labelled points overlap. A dose of [35S]cysteine was injected into 24 sites across the side of five Lincoln ewes. After 48 hours a second injection was administered to one site on each ewe, followed by an injection into another site every two hours until all 24 sites had been labelled twice. Three days later all 24 sites were injected again. Following autoradiography the distance between radiolabelled points was traced using a digitizer (50 fibres per site). A linear increase in length between points 1 and 2 was observed between sites (r2 = 0.920) and the regression equation showed the fibre increased in length by 29.2 µm per site (P < 0.01). However, a linear decrease in length was observed down (P < 0.001) but not along (P = 0.813) the midside over the period delineated by injections 1 and 3. Removing the effect of site gave growth rates that reflected the overall mean of 28.9 µm/hour for all sites. This method could be used to determine changes in growth rate over a few hours or the response to a growth factor, hormone or nutrient over a time course of several hours.

Mechanisms linking the somatotropic axis with insulin: Lessons from the postpartum dairy cow - Lucy MC (Proceedings of the New Zealand Society of Animal Production, 2004)
Growth hormone (GH; synonymous with somatotropin) coordinates nutrient partitioning in dairy cattle by increasing glucose synthesis in liver and mobilizing lipid from adipose tissue. The effects of GH are opposite to the glucose-clearing effects of insulin. It is not surprising, therefore, that physiological mechanisms have evolved which coordinate the actions of both hormones. There appears to be direct communication between the somatotropic axis and the insulin axis. The manifestation of this interaction is clearly evident in postpartum dairy cows where blood GH concentrations are high and blood insulin concentrations are low. Diabetic states in humans [either type 1 diabetes mellitus (insulin-dependent) or type 2 diabetes mellitus (insulin resistance)] also lead to abnormal function within the somatotropic axis; evidence that insulin and GH are closely linked in humans. Cattle and humans share common elements of somatotropin physiology perhaps because common regulatory mechanisms control the expression of key genes within the axis of each species. This review will discuss the mechanisms linking insulin and somatotropin in cattle and humans. Similarities between diabetic states in humans and low-insulin states in postpartum cows will be highlighted.

Milk production and grazing behaviour during early lactation of three strains of Holstein-Friesian dairy cows managed in different feeding systems - Rossi JL; MacDonald KA; Thorrold B; Holmes CW; Matthew C; Hodgson J (Proceedings of the New Zealand Society of Animal Production, 2004)
The objective of this work was to compare individual intake and grazing behaviour of different strains of Holstein-Friesian dairy cows. Strains tested were high breeding worth 1990’s Holstein-Friesian of overseas (OS90) or NZ origin (NZ90), and a 1970 NZ strain of Friesian (NZ70), farmed under different feeding systems defined by feed allowance per cow per year. Feed allowance ranged from 4.5 to 7.0 t DM cow-1 year-1, based on different stocking rates and supplement inputs. Each system (one strain at one total annual allowance) was managed using a common set of decision rules and all the strains were in similar body condition score (BCS) at calving. Milksolids production, liveweight and BCS were measured routinely, and during September 2002 (55-75 days in milk) daily DMI and digestibility (DMD) were estimated for each cow by the n-alkane method. Grazing behaviour was observed visually. Daily milksolids yield (per cow and per 100 kg LW) were similar for NZ90 and OS90, which were higher than NZ70 (p<0.01). At the start of the season OS90 cows were heavier (p<0.05) than cows of the other two strains and NZ90 cows heavier (p<0.05) than NZ70 cows, however they were similar in BCS. During September OS90 cows were just slightly heavier than the other two strains (p=0.16), but with lower BCS (p<0.01). Between the start of the season and September, LW and BCS decreases for OS90 cows were significantly higher (p<0.05) than for cows in the other two strains. Slightly higher DMI (per cow and per 100 kg LW) were recorded for the NZ90’s than for NZ70 and OS90. Grazing time, ruminating time or biting rate was similar across strains. These results suggest that the OS90 was not able to eat sufficient pasture and used more body energy reserves to produce similar MS yield as NZ90.

Modelling farm systems with once-a-day milking - Beukes PC; Thorrold BS; Wastney ME; Palliser CC; Clark DA (Proceedings of the New Zealand Society of Animal Production, 2004)
Our objectives were to investigate how a cow model, "Molly", deals with once-a-day milking and to use "Molly" in a Whole Farm Model to explore farm systems where once-a-day milking might produce results on a per hectare basis comparable to twice-a-day milking. We compared our model outputs to observed data from a Milking Frequency trial run by Dexcel at a research farm in Taranaki. Changing the rate constants for milk removal and degradation of the lactation hormone complex in "Molly" resulted in the model expressing the acute and chronic effects of once-a-day milking. The once-a-day cow model fed ad lib seasonal grass pasture showed a decrease in milksolids yield (kg/cow) of 31% in Friesians compared to the observed 28%. When we used .Molly. in the Whole Farm Model it showed that farm performance with once-a-day milking was 1135 kg milksolids/ha when a Friesian herd was stocked at 7% higher and their lactation was extended by 14 days compared to a twice-a-day herd (1132 kg milksolids/ha). We conclude that farm performance with once-a-day milking is strongly dependent on selecting cows with higher lactational persistence under once-a-day milking and managing for extended lactations.

Northern analysis of temporal and spatial variation in milk protein expression during early mammary involution in dairy cows - Molenaar AJ; Farr VC; Oden KE; Wheeler TT; McMahon CD; Good LL; Stelwagen K; Singh K; Davis SR (Proceedings of the New Zealand Society of Animal Production, 2004)
Understanding the mammary responses that occur at the cessation of milking whether natural, forced, or which occur at the end of the milking season and during the subsequent initiation of mammary involution (Holst et al., 1987; Hurley, 1989) has relevance in milk production traits such as milk yield, persistency and extended milking intervals and may suggest ways of improving milk production in later lactation (Stelwagen, 2001) (Vetharaniam et al., 2003). The proportions of secretory, support and milk storage components vary significantly between the alveolar (main milk synthesis), peripheral (a several cm thick layer of secretory tissue surrounding the main alveolar bed) and cisternal (main milk storage area adjoining the teats) compartments of the udder (Farr et al., 1996; Sordillo and Nickerson, 1988; Weber, 1977). In addition, variations in the local proportions of these components has also been observed in the main alveolar areas and dramatic variations of gene expression depending on the local mammary tissue composition have been observed (Molenaar et al., 1992). Ignorance of the effect on gene expression profiles resulting from sampling variations could lead to improper interpretation of experimental results and hence there is a need for more extensive spatial and temporal surveys to be done.

Pasture biotechnology - not as you know it - Elborough KM; Hanley Z (Proceedings of the New Zealand Society of Animal Production, 2004)
As part of an ongoing project to identify quantitative trait loci (QTL) for economically important traits in New Zealand dairy cows, a vaccine trial was conducted to measure the antibody response of 10 week old Friesian-Jersey crossbred calves to two antigenic compounds of a clostridial vaccine (Clostridium novyi B and Clostridium tetani toxoids). Blood samples were collected from 469 calves prior to vaccination at 10 weeks of age, prior to re-vaccination at 13 weeks of age and at 16 and 22 weeks of age. ELISA assays using conjugated rabbit anti-bovine IgG were conducted for both toxoids. Correlations and explanatory variables were calculated using correlation and general linear model (GLM) procedures in SAS. Antibody response to both toxins were relatively low after the first vaccination (week 13), but were boosted to high levels after revaccination (week 16). GLM analysis revealed a moderate sire effect contributing to the variability seen in the 13 week test against C. tetani (P=0.001) and the 16 week test against C. novyi (P=0.01). This variation in individual antibody response will be used in future research to identify genetic factors controlling the acquisition of immunity.

Phenotypic attributes of postpartum ovulation and other fertility measures in Friesian-Jersey crossbred cows - Sanders KM; Bennett R; Spelman R (Proceedings of the New Zealand Society of Animal Production, 2004)
Reproductive performance is an important factor contributing to on-farm efficiency and profitability. The purpose of this study was to define and quantify a set of fertility phenotypes for 352 Friesian-Jersey crossbred heifers, and determine key factors contributing to these indicators. Heats were observed and recorded prior to herd start of mating, and CIDRs were used to treat non-cycling heifers (51) once mating started. Progesterone samples were collected twice weekly, and luteal activity was identified where concentrations were >0.9 ng/ml for blood and >3.0 ng/ml for milk samples. Commencement of luteal activity was defined by either one elevated sample (CLA1) or two consecutive elevated samples (CLA2). For untreated heifers, the average intervals to CLA1 and CLA2 were 29.6 days (sd=14.3) and 34.1 days (sd=16.9) respectively. Other phenotypes were evaluated for conception and intervals to first heat, first service and successful service. Significant relationships were established between body condition score (BCS) at calving and the intervals to CLA. For every unit decline in BCS at calving there was an increase of 7.4 days to CLA1 and 8.8 days to CLA2. The evaluated fertility phenotypes, and their key contributing factors will be used in another study to identify related quantitative trait loci (QTL).

Presidential Address 2003: The New Zealand Society of Animal Production - another 20 years - Morrow C (Proceedings of the New Zealand Society of Animal Production, 2004)
Historically, the Presidential address falls into one of three general categories, 1) the President’s area of interest in animal production, 2) the concerns and future direction of animal production or the Society or 3) a review of Society activities. Andrews (1963), Everitt (1973), Smith (1984) and Nicol (1992) have periodically reviewed the Society activities and it seems timely to do so again in 2003 …

The process and technologies of gene discovery to application in dairy cattle - Snell RG (Proceedings of the New Zealand Society of Animal Production, 2004)
The heady days of biotechnology that were driven by the assumption that biotechnology would solve all biological problems with simple solutions, are over. The ‘biotech’ investment in the mid to late 1990’s was driven predominantly by commercial and scientific enthusiasm, ignoring biological, commercial and regulatory realities. In the post-bubble environment, the dairy industry, including ViaLactia Biosciences and our research partner Livestock Improvement Corporation are undertaking a research program endeavouring to align the expectations of the market, the investors and the limits of technology. In general, the thrust has been to utilize existing or develop new biological resources and where they are required and not available, tools for discovery. Much of the on-going challenge is in defining the opportunity (desired phenotype), predicting technological developments, large scale investment in the public domain and matching the approach to the problem within time and budgetary constraints. Our approach will be presented with some examples of successes.

Red deer as a novel ruminant model for nutritional and genetic influences on maternal expression of foetal and neonatal growth - Asher GW; Archer JA; Stevens DR (Proceedings of the New Zealand Society of Animal Production, 2004)
The red deer species (Cervus elaphus) is represented by morphologically disparate subspecies that freely crossbreed. All are highly seasonal breeders adapted to cold-temperate climates characterised by extreme annual oscillations in temperature and feed availability. Calves are born in summer following relatively long average gestation lengths of 234–250 days (depending on subspecies), with >70% of pregnancy mass acquired over spring/early summer. The ability of the smaller red deer hind (100 kg) to successfully gestate, birth and rear crossbred (e.g. wapiti x red deer) progeny of 40% increased foetal and post-natal growth potential is quite remarkable, and raises numerous questions about mechanisms of maternal and foetal control of reproductive processes. Recent research on moderate variations in late gestational nutrition to red deer hinds gestating red deer foetuses has revealed an interesting phenomenon in which nutritional influences on foetal growth trajectory appears to influence gestation length to ensure optimisation of birth weight (and, hence, neonate survival). This is quite contrary to expectations for sheep and cattle, but may have parallels amongst other wild ruminant species. Interestingly, hinds gestating crossbred (wapiti x red deer) foetuses of greatly increased growth potential appear unable to adopt such compensatory mechanisms, with hind under-nutrition leading to reduced birth weight relative to ad-libitum fed controls. These observations hint at some interesting and useful future research on mechanisms of maternal and foetal growth control in red deer.

Relation between sweating and wool yellowing in Merino and Romney sheep - Sumner RMW; Ashby MG; Craven AJ (Proceedings of the New Zealand Society of Animal Production, 2004)
Five adult Merino and five adult Romney ewes with 7 months growth of fleece were subjected to nine different environmental challenges in a climate controlled room on consecutive days where the temperature humidity index (THI) was varied from 74.2 to 91.3 for up to 7 h at each exposure. Secretions were collected from glands in the skin on the back, midside and belly regions of each sheep. The sheep were shorn 5 months later. There was a significantly curvilinear increase in total skin gland output and the rate of secretion of titratable alkalinity and potassium ions with increasing THI. Romney sheep had a higher secretion rate than Merino sheep with no significant site effect. The rate of secretion of titratable alkalinity and potassium ions by the skin glands were both strongly related to tristimulus (Y-Z) of the fleece at shearing (base yellow) (R2 = 0.93, 0.92) and after incubation of the wool sample at 40°C and 100%RH for 6 d (challenge yellow) (R2 = 0.96, 0.95). These data indicate a particularly strong relationship between the rate of secretion of titratable alkalinity and potassium ions by the skin glands and the later propensity of the fleece to develop a yellow discolouration.

Relationship between intramammary infection and teat characteristics - Lopez-Benavides MG; Williamson JH; Walters JB; Hickford JGH (Proceedings of the New Zealand Society of Animal Production, 2004)
The relationship between teat characteristics and intramammary infection (IMI) was investigated in 111 cows. These cows were scored visually on teat shape, teat-end shape and teat pigmentation. Subsequently, foremilk quarter samples were collected weekly for 14 weeks from calving to assess bacterial presence and somatic cell count (SCC). Teat shape and teat-end shape were combined and termed teat type. The distribution of teat type was cylindrical- round (34%), funnel-round (21%), cylindrical-flat (16%) and bottle-round (9%). Approximately 44% of teats were fully pigmented (black/brown) while 25% of teats were pigmented over less than 20% of the surface area. The frequency of quarters that never became infected during the trial period was 78.4% and the mean SCC was 69,000 cells mL-1. Among the infected quarters, the most frequently isolated pathogens were Corynebacterium bovis (45%), coagulase negative staphylococci (CNS) (43%) and Streptococcus uberis (6%). Analyses showed no associations between teat characteristics and quarters not becoming infected, or between teat characteristics and bacterial pathogens in infected quarters.

Remote automatic selection of cows for milking in a pasture-based automatic milking system - Jago J; Bright K; Copeman P; Davis K; Jackson A; Ohnstad I; Wieliczko R; Woolford M (Proceedings of the New Zealand Society of Animal Production, 2004)
New Zealand pastoral dairy farming presents unique challenges for combining automatic milking systems (AMS), including long walking distances, large herds, year round pasturing and a predominately fresh pasture diet. This paper describes a system designed to minimise walking, maximise the efficiency of AMS utilisation and enable control of individual cow milking frequency by remotely selecting cows for milking up to 400 m from the dairy. Cows report to a selection unit (SU) located in the centre of a block of pasture and linked via raceways to the AMS. Entry is via one-way gates and exit via a computer controlled drafting gate, which directs the cow either to the dairy or the paddock depending on time since last milking. A communication cable connects the SU to the AMS server in the dairy. Cows wear an electronic identification device. Water and pasture access act as incentives for cows to enter the SU. Cows readily learned to use the SU and were observed visiting the unit at every hour over 24 hours. Twenty-seven cows were assigned to either a 6h or 12h minimum milking interval (MMI). On average, cows visited the SU 4.5 and 5.5 times/d for the 6h MMI and 12h MMI groups, respectively, and achieved a milking frequency of 1.9 and 1.4 milkings/d, respectively. Results showed that milking frequency can be controlled via a system for remotely selecting cows for milking and that access to fresh pasture is a strong factor in motivating cow traffic through the SU.

Resilience to nematode parasite challenge in industry and AgResearch selection flocks - Morris CA; Amyes NC; Bisset SA; Mackay AD (Proceedings of the New Zealand Society of Animal Production, 2004)
A large-scale industry project on the resilience of lambs to nematode parasite challenge was undertaken in 2001/02 and 2002/03, to evaluate the feasibility of recording standardised age at first drench (StAge) and postweaning weight gain under nematode challenge, and to estimate genetic differences among flocks. The project involved 15 Romney flocks from two ram breeding groups, with some flocks having been part of an earlier AgResearch study of the genetics of resilience traits. This provided the opportunity to assess any correlated changes in resilience over time (where direct selection over that time period in the industry flocks had been applied to productivity traits, but not to resilience), and to compare the industry performance with AgResearch Resilient-selected and Control lines. The overall estimates of heritability for StAge and weight gain (2 time periods: Gain1 and Gain2) were 0.14 ± 0.014, 0.30 ± 0.015 and 0.15 ± 0.007, respectively. Genetic correlations between StAge and either Gain1 or Gain2 were 0.30 ± 0.06 and 0.41 ± 0.06, respectively. Genetic differences for all traits between the two industry groups were small and not significant. The genetic differences of the current industry-group means (all 15 flocks) above the AgResearch Control line were small (0.8 days, 0.5 kg and 0.9 kg, respectively). In comparison, the genetic differences of the AgResearch Resilient-selected line over the Control line after eight years of selection were 19 days, 0.7 kg and 1.4 kg (11, 8.3 and 9.6% of the industry means). The results confirm that while selection for increased resilience is feasible (although very time-consuming) under commercial conditions, a ram breeder would need to consider an index approach which combined production and resilience traits, to make best use of his animal resources.

Sheep nutrition, fetal growth and human health - Harding JE; Bloomfield FH; Oliver MH (Proceedings of the New Zealand Society of Animal Production, 2004)
In 2003 the Centre of Research Excellence (CoRE) for Growth and Development was formed. The purpose is to conduct research into growth and development, focussing particularly on the issues of pre ñ and post natal growth and its implications for human health. The medical challenges for the developed world are those associated with the nutritional environment, obesity and the associated illnesses of diabetes and cardio ñ vascular disease. There is evidence linking the propensity for these diseases to the nutritional status of the fetus in the first trimester of pregnancy and the interaction of this status with nutrition in the immediate post ñ natal period. In this respect the problem differs from the issues considered by animal production. Here the last trimester of pregnancy has received the most attention, and few domestic animals live long enough for cardio ñ vascular problems to arise. Nevertheless the skills and methods of investigation developed by animal scientists can be applied to these new problems.

A split night photoperiod does not mimic effects of a long-day photoperiod on growth in weaner red deer stags - Crowley V; Barrell GK; Keeley MJ (Proceedings of the New Zealand Society of Animal Production, 2004)
In sheep, the effects of a long day photoperiod can be mimicked by providing a ‘split night’ light stimulus during the dark phase of a short-day photoperiod. This study tested the hypothesis that a similar response to a split night photoperiod occurs in deer. From 6 May until 3 September 2003, three groups of weaner red deer stags (n = 10) were subjected to: natural daily photoperiods (short days, experiencing the normal seasonal pattern of daylight), a long day photoperiod (16L:8D, where L = h of light, D = h of darkness) or natural daily photoperiods with a period of 1 h of light (circa 370 lux) during the dark phase (split night). For the first 3 months, liveweight gain was similar in all groups (approx. 140 g/day). However, growth of long-day exposed animals began to exceed that of the other treatments so that after 6 August their mean liveweight was significantly (P < 0.01) greater than that of the other groups. From 26 June to 3 September mean liveweight gain was, 324 ± 28.3, 209 ± 23.9 and 186 ± 20.6 g/day for long day, split night and short day photoperiod groups, respectively. The long day group had the highest voluntary feed intake and appeared to initiate antler pedicle growth and testicular enlargement earlier than the other groups. Plasma prolactin concentration was elevated (P < 0.01) by the long day treatment (mean for long day group at 9 July = 33.4 ± 4.09 versus means of 6.9 ± 3.75 and 2.9 ± 0.99, ng/ml for split night and short day groups, respectively). These results show no stimulatory effect of the split night photoperiod on growth of red deer. It is concluded that some of the photoperiodic signals that can cause physiological changes in sheep are not effective in deer and, hence, there are differences in the underlying mechanisms of photoperiodism between these two species.

A survey of goat meat acceptability in Japan - Ozawa T; Lopez-Villalobos N; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2004)
A questionnaire survey was designed to gauge consumer interest in goat meat. The questionnaire was responded to by 98 households living in or near Tokyo. The main results of the survey are as follows. 1) Impression of goat meat; 61% of the respondents indicated that goat meat was “not common in their home”. 2) Consumer experience; only 16% of the respondents had experience of eating goat meat and they felt goat meat is “smelly” (50%), “tender” (38%) and “delicious” (31%). 3) The two main reasons why consumers have not eaten goat meat were “lack of purchasing opportunity” (78%) and “don’t feel like eating it” (18%). 4) Options to promote goat meat consumption; 52% of respondents who have not eaten goat meat were prepared to purchase if it was available in the supermarket at a reasonable price and if recipes were added with the meat package. 5) Reasons for people not purchasing goat meat included “dislike of new meat” and “pity for the goat”. These results show that goat meat can be promoted to the Japanese households as “a new product” if the price is reasonable and recipes are added to the package. However, a considerable number of market strategies need to be implemented to achieve the acceptance of goat meat by Japanese consumers.

Understanding shepherding within lambing, and organic farming systems through acknowledging cultural, community and individual influences - Fisher MW; Small BH; Mackay AD; Kenny GJ; Jerebine BC; Parminter TG (Proceedings of the New Zealand Society of Animal Production, 2004)
The way we farm depends on the species farmed, the environment, and on our beliefs, prejudices and expectations. A model was developed to consider cultural influences, community ethics, and individual goals to help understand shepherding and organic farming. Assisting sheep at lambing is reinforced by cultural expectations of what shepherds should do. Different management strategies are used depending on the sheep, their environment, and the costs and practicalities of supervision. Finally, the weight given to different factors may depend on the motivation of individuals in deciding to "live with the flock" or find better ways of managing lambing. Reflecting the different goals of agriculture, individuals were motivated to convert to organic farming by economic returns, the environment, chemical use, food safety and quality, animal health and welfare, and a desire to maintain rural communities. The safety of chemicals, food quality, and the environment are central to understanding the value of organics to the community. Finally, organic farming is informed by stories of “being at one with nature” An understanding of the different beliefs that inform us of the way farming is, or should be, may result in a greater shared understanding of complex issues, and more equitable farming practices.

Use of breeding values for live weight to calculate individual live weight targets for dairy heifers - Bryant JR; Holmes CW; Lopez-Villalobos N; McNaughton LR; Brookes IM; Verkerk GA; Pryce JE (Proceedings of the New Zealand Society of Animal Production, 2004)
Replacement heifers need to reach specific target live weights (LW) to ensure they calve as two year olds, and subsequently achieve high milk yields and good fertility. Currently, different LW targets are recommended for heifers based on their expected mature LW according to appearance or breed. However, the mature LW is difficult to estimate without knowledge of the animals. genetic potential for LW. The objective of this paper is to develop and validate a growth model which uses estimated breeding values for LW (EBV LW) of individual heifers of any breed to calculate target LW from birth to maturity. Predicted live weights are presented for a range of four EBV LW, from –40 to 100 kg. These values were very similar to other published target values. Data from the Dexcel Holstein Friesian Strain Trial was used to validate the model with respect to LW and age at puberty. For LW at puberty the predicted values were significantly correlated (P<0.05), but were marginally higher (3-5%) than the actual values. A report can be formulated to enable farmers to identify individual heifers which are below (or above) their target LW at any date

The use of cDNA microarrays to investigate changes in gene expression in the involuting bovine mammary gland - Singh K; Molenaar AJ; Stelwagen K; Farr VC; Good L; Swanson K; Oden K; Wheeler T; McMahon C; Henderson H; Wilson T; Hyndman D; et al. (Proceedings of the New Zealand Society of Animal Production, 2004)
The molecular mechanisms and pathways involved in involution of the udder and which coordinate and regulate the processes of cell death and proliferation after weaning/cessation of milking in ruminants, are poorly understood. The aim of this study was to use cDNA microarray analysis to identify genes and pathways involved in involution of the bovine mammary gland. Ultimately, because this process underpins lactation traits such as persistency and mammary responses to milking frequency (Stelwagen, 2001; Vetharaniam et al., 2003), this information may allow the development of novel strategies for improving milk production especially in the later stages of lactation. Involution of the bovine mammary gland was induced by abrupt termination of milking in 48 non-pregnant Friesian dairy cows at mid-lactation (average days in milk, 92 ± 3) …

The use of microarrays to investigate gene regulation in the bovine mammary gland during Streptococcus uberis mastitis - Swanson KM; Henderson HV; Farr VC; Davis SR; Oden K; Stelwagen K; Molenaar A; Singh K; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 2004)
Bovine mastitis is one of the most costly dairy-based diseases worldwide with an estimated $60 M loss to New Zealand per season. Mastitis infections are a result of bacterial or fungal pathogens becoming established in the udder, and are detected by the increase of somatic cells in the mammary gland, bacteriology data and physical signs of infection. In New Zealand, mastitis is usually a result of a gram-positive bacterial infection (Brookbanks, 1966). Of these bacteria, Streptococcus uberis is emerging as one of the most prevalent causative organism of mastitis in New Zealand (McDougall, 2002). It resides naturally in the environment making prevention of the disease difficult. Currently the main means of controlling the disease is through administering antibiotics following identification of infection. The mammary gland is protected from invasion by the activation of non-specific (innate) and specific defence mechanisms. The innate immune response is the predominant defence during the early stages of infection and is induced rapidly at the site of infection (Sordillo et al., 1997). Although the local mammary innate immune response has been widely investigated, studies have focussed on known antibacterial compounds and little is known about the novel compounds in bovine milk and how these contribute to the defence system of the mammary gland. The mechanism by which the mammary gland innate immune system is active against S. uberis is poorly understood. By developing an understanding into the way S. uberis induces an immune response in the mammary gland and the effect of infection on mammary gland metabolism we may identify components which can be utilised to either reduce the symptoms of/or prevent or cure S. uberis mastitis.

What the bovine genome project means to New Zealand - McEwan JC; Crawford AM (Proceedings of the New Zealand Society of Animal Production, 2004)
The sequencing of the bovine genome commenced in December 2003 and sequencing is planned to achieve a seven-fold coverage by November 2005. This along with previous physical mapping efforts will allow a high quality genomic assembly to be produced. The sequencing is being undertaken by Baylor College of Medicine in Texas. Separately, the Michael Smith Genome Science Centre in Vancouver will sequence 10,000 full length non-redundant bovine mRNAs. The assembled genome will be annotated in collaboration with the Ensembl project at the Sanger Institute, UK, and will be publicly available on genome browsers such as NCBI, Ensembl and UCSC. In the interim the raw sequence information is being made available at NCBI within days of being generated. As well as providing DNA sequence, the program will identify more than 50,000 microsatellites and one to two million SNPs. The availability of this information will transform and accelerate ruminant genomics research. Similar genome sequencing efforts in human and laboratory species have greatly increased the rate of gene variant discovery underlying quantitative trait loci. It will also aid our understanding of gene expression control. New Zealand stands to benefit directly from this work, because of its strong reliance on grazing livestock for export income and its internationally competitive beef and dairy industries. The project is funded by an international consortium involving CSIRO Australia, Genome Canada, New Zealand, National Human Genome Research Institute of the U.S. national Institutes of Health (NHGRI), U.S. Department of Agriculture (USDA), the State of Texas, The Kleberg Foundation, U.S. Beef Council, and Texas and South Dakota Beef Councils. Significantly, the National Institutes of Health have strongly supported the project as a consequence of its human health implications. This project benefited greatly from a previous international genomic collaboration to physically map the bovine genome, and it provides an excellent example of benefits obtained from international research consortia co-investing in public domain infrastructural projects.

Zinc dipping can help reduce wool yellowing - Reid TC; Urquhart RA (Proceedings of the New Zealand Society of Animal Production, 2004)
On one farm dipping sheep once or twice with zinc sulphate had no effect on the yellowness of wool at shearing. When data from this farm were combined with data reported earlier, the reduction in yellowness was linearly related to the yellowness of the control group (P = 0.091, 0.032 for dipped once or twice, respectively). On another farm, groups of 20 rising two-tooth New Zealand Halfbred ewes were treated in February by either dipping with zinc sulphate solution (2.45 g Zn/l) or dosing with a zinc bolus. Both treatments reduced the yellowness of belly wool at crutching (May) (Y-Z = 4.31, 2.13 and 1.87 for control, bolus and dipped sheep, respectively, P<0.01), but had no effect on the yellowness of the flank wool (Y-Z = -0.16, -0.27, -0.06). Zinc concentrations in clean wool (initial concentration = 78.5 mg/kg) were increased in all three groups at crutching but the differences were significant for the dipped group only (zinc concentrations = 160, 211, 340 mg/kg for control, bolus and dip, respectively, P<0.001). Thus, in some cases, increasing the concentrations of zinc in wool can reduce yellow discolorations at shearing. The effect will be greatest where wool from untreated sheep is yellowest. This could prove to be a useful method to improve wool quality on some farms.

Achieving 4% productivity: Implications from a longitudinal study of farmer learning in dairy farming - Gray DI; Parker WJ; Kemp EA (Proceedings of the New Zealand Society of Animal Production, 2003)
The New Zealand dairy industry needs to achieve 3 to 4% pa gains in productivity. Accomplishing this on-farm will require continuous innovation by farmers. Innovation may result from the refinement of existing practices, or the introduction of new practices or technologies. Farmer learning will be pivotal to the rate of innovation. However, despite its importance, relatively little is known about farmer learning. We investigated the tactical feed management processes used by two high-performing dairy farmers over summer-autumn for three years, using a multiple-case study design. Learning undertaken by the farmers could be classified within three broad domains (the production and management systems, and the environment), but normally involved the interactions between at least two of these. Two stimuli initiated learning: the occurrence of extreme conditions or the introduction of a new management practice. Different learning processes were identified with respect to these. This study provides a framework for extension agents to identify the “knowledge gaps” farmers need to close in order to improve productivity. It also assists developers of a new technology, since farmers want to know how the new technology impacts on their production systems, responds under a range of conditions, and is best incorporated into their management.

The Alliance Central Progeny Test: Preliminary results and future directions - Campbell AW; Knowler K; Behrent M; Jopson NB; Cruickshank G; McEwan JC; Wilson T (Proceedings of the New Zealand Society of Animal Production, 2003)
The Alliance Central Progeny Test (CPT) was established in 2001 with the aims of improving the carcass dollar value of sires under the Alliance grading system and establishing links among ram breeders so Alliance can identify the best rams for their clients. In the 2002/2003 season 22 terminal sires from nine different breeds were evaluated. Each ram was mated to 30 ewes at the AgResearch Woodlands research farm. Progeny numbers for each ram ranged from 13-46. Initial early results showed that breeding values for weaning weight were well spread among sires (range over 2.5 kg) indicating there were genetic differences among sires used. Lambs were slaughtered in four slaughter groups between December 16th , 2002 and March 11th , 2003. Analyses from the full data set will be available from May 2003. The next cycle of the Alliance CPT begins with mating in April, 2003, with an emphasis on dual-purpose sires.

Approaches in developing a successful trans-cervical AI programme for farmed deer - Rhodes L; Pearse AJT; Asher GW (Proceedings of the New Zealand Society of Animal Production, 2003)
Trans-cervical artificial insemination (AI) in farmed deer has emerged as a highly successful reproductive tool that can rapidly increase rates of genetic gain in farmed deer. Conception rates in excess of 70% are confidently achieved if all aspects of a simple programming prescription are followed. Hind nutrition, attention to hygiene and reducing individual animal and herd stress levels appear to be key factors, over and above that of semen quality and insemination skills. Many factors cumulatively affect success or failure within the typical eight week breeding season. Combinations of care and attention to detail are essential. This paper considers the interplay of these factors in advising choices made that underpin a successful trans-cervical AI programme based on commercial experiences.

Assessment of fleece cover in crosses between Coopworth, Dorper, Damara, New Zealand Wiltshire, Poll Dorset and Suffolk sheep - Merrick NC (Proceedings of the New Zealand Society of Animal Production, 2003)
Fleece cover was assessed over 10 body regions for nine pure and crossbred combinations of progeny from longwool, short-wool and hair breeds of sheep. Assessments were made between docking and hogget shearing. Visually assessed fleece-cover scores varied by less than 0.35 units within day (P = 0.757) and 0.21 units between days (P = 0.120). Differences of 0.2 units between assessors (P<0.05) were tolerable in a scoring system utilising whole measurement units. The average fleece cover of Wiltshire and Dorper x Wiltshire lambs was 1.14 and 0.92 units less than Coopworth lambs at weaning (P<0.01) but no different at hogget shearing (P = 0.17). The temporary reduction in fleece cover at weaning was attributed to shedding of fibres from the fleece. All breed combinations studied produced between 29 and 67% less fleece than Coopworth hoggets (P<0.001). However, without the ability to synchronously shed their fleece, first generation crossbred progeny required shearing as hoggets.

Beef traceability systems in Japan - how should New Zealand prepare? - Ozawa T; Lopez-Villalobos N; Blair HT (Proceedings of the New Zealand Society of Animal Production, 2003)
Interviews were held with National Federation of Agricultural Cooperative Association (NFACA), Ministry of Agriculture, Forestry and Fisheries (MAFF) and New Zealand Meat Board staff to describe current beef traceability systems operating in Japan following the BSE incident there in 2001. Some suggested actions for the New Zealand beef industry to become more competitive against domestically produced beef are described from a traceability perspective. It is concluded that there is no sustainable, complete (from farm to consumer) beef traceability systems being operated in Japan, not only by domestic producers or retailers, but also by overseas companies. Domestic traceability systems are either facing financial problems (NFACA system) or functional problems (MAFF system). This means that if New Zealand adopts a farm to consumer traceability system in the Japanese market, it will be the pioneer and will be recognised, as "clean and green", not only by nuance, but also in practice by the Japanese consumer. The main problem for New Zealand adopting such a traceability system in the Japanese market is balancing anticipated expenses versus expected financial return to the New Zealand beef producer.

The benefits of across-flock analysis - Clarke JN (Proceedings of the New Zealand Society of Animal Production, 2003)
Recent and current developments by Sheep Improvement Ltd (SIL) to provide animal evaluations for a wide variety of flocks using Best Linear Unbiased Prediction (BLUP) methods have encouraged breeders to compare animals bred in different breeding flocks. The data requirements and analytical models needed for BLUP to handle this task are discussed with major emphasis on sire-referencing as a method for achieving adequate genetic linkages among flocks by which animals bred in different flocks may be compared. Despite the high ability of BLUP to accommodate this task and the benefits perceived by many breeders, few specific studies of potential benefits for particular breeding schemes have been reported. In general terms, the impact of across-flock evaluations on annual rates of genetic gain varies for different traits, mating strategies, flock and industry structures. They may not always be cost effective in comparison to within-flock performance selection, especially for larger flocks and when the costs of implementing the flock structures needed to make them accurate and effective in evaluating and disseminating genetic merit are taken into account.

Calculating animal performance from limited liveweight measurements of the population - Wake GC; Pleasants AB (Proceedings of the New Zealand Society of Animal Production, 2003)
We consider the problem of estimating the distribution of carcass weights in a flock of animals from estimates made on a truncated sample. This arises when a farmer chooses the heaviest lambs for slaughter and then measurements are made by the meat processor. This enables a farmer to answer two questions: what proportion of the animals remaining exceed a nominated carcass weight, and/or what carcass weight is exceeded by a nominated proportion of the population? Estimates of these statistics and their uncertainties are derived and are exact if the animal weights are normally distributed. These calculations can be the basis of decisions about future feeding and drafting strategies, important for farmers producing animals on contracts for future delivery. An example is given based on 1000 lambs using a cut-off weight of 15.5 kg with mean of this upper group of 16 kg. Using a realistic estimate of a standard deviation (of the weighing scales) of 0.3 kg, this gives an estimated mean of 14.6± 0.04 kg, with a standard deviation of 0.94±0.044 kg, and that 75% of the lambs in the population exceed 13.9±0.07 kg. The proportion of lambs that exceed 14.5 kg is then between 51.3% and 55.7%.

Can dipping sheep with zinc sulphate reduce wool yellowing? - Reid TC; Urquhart RA (Proceedings of the New Zealand Society of Animal Production, 2003)
On each of four farms, groups of ewes were either not dipped, dipped once or dipped twice with zinc sulphate solution (20 g/l). Base and challenge yellowness were determined on core wool samples collected at shearing. Dipping with zinc sulphate increased the zinc concentration of wool at shearing from 154 (range 77-321) to 421 (range 116- 1140) (dipped once) or 806 (range 143-1920) mg/kg (dipped twice). Zinc sulphate dipping had no effect on the base yellowness of wool on three farms, but significantly reduced wool base yellowness on the fourth farm (Tristimulus (Y- Z) = 9.0 vs. 7.8 vs. 8.5 for control, dipped once and dipped twice, respectively) (P<0.01). In the laboratory, wool samples from all farms were significantly less yellow after challenge when sprayed before challenge with zinc sulphate solution than when sprayed with water (9.9 vs. 10.9; 7.1 vs. 10.0; 8.3 vs. 10.6; 11.3 vs. 13.1) (P<0.001). There was a significant relationship (R2 = 83.4%, P<0.001) between the changes in zinc concentration resulting from zinc dipping and the changes in yellowness of the wool with challenge. These results indicate that dipping sheep with zinc may reduce discoloration of greasy wool at shearing under environmental conditions in which yellowing is maximised.

Comparison of multivariate statistical methods for the prediction of reproductive performance of Holstein Friesian cattle - Harris BL; Pryce JE; Verkerk G (Proceedings of the New Zealand Society of Animal Production, 2003)
The objectives of this study were to predict success or failure at mating (1/0) using information on 168 first lactation dairy cows from the Dexcel Strain Trial. The farmlets were established by allocating heifers from three genetic strains to eleven groups. The groups were managed under a range of feeding systems, ranging from moderate to generous allowances. Measurements were taken on milk, fat and protein yields, liveweight and condition score and variables derived from these used as predictors of success at mating in a series of models. Reproductive measures used for analysis were cows in calf at 42, 49 and 56 days after the planned start of mating. Three statistical methods were used to determine suitable predictive models of success at mating: logistic regression, discriminant analysis and partition analysis. Partition analysis was the best method of prediction. Kappa values, measuring the degree of agreement between observations and predictions ranged between 0.32 and 0.38 for discriminant analysis, 0.41 and 0.44 for logistic regression and 0.70 and 0.74 for partition analysis. The partition analysis produced a set of rules for predicting likely success at mating. Important rules were CS > 4.75 in month three of lactation and calving before week four after the start of calving for the herd.

Conjugated linoleic and trans-vaccenic acids in grass-fed beef and lamb - Knight TW; Morris CA; Purchas RW; Agnew M (Proceedings of the New Zealand Society of Animal Production, 2003)
Cis-9 trans-11 conjugated linoleic acid (CLA) found in ruminant milk and meat has several human health benefits of which the anti-cancer effect is the most prominent. Trans-vaccenic acid (TVA) is a precursor of CLA and can be considered as another dietary source of CLA. This paper uses data from three published papers to compare the CLA and TVA concentrations in the longissimus lumborum muscle (LL) from cattle and lambs, to determine the within- group variation, and to identify factors influencing this variation. The paper discusses the contribution lean beef and lamb can make to the estimated human daily required intake (DRI) for CLA. The CLA and TVA content was measured in the LL from two groups of cattle (n = 15 and n = 100) and two groups of lambs (n = 30 and n = 12). CLA and TVA concentrations in the total fatty acids (TFA) was higher (P<0.001) in lamb than in beef. The coefficients of variation within each group of animals ranged from 23-41% for CLA and 25-68% for TVA, indicating a large variation in the concentration of these fatty acids among animals. A number of factors contributed to these differences but the largest difference was found in lambs, where there was a 41% higher (P<0.01) CLA concentration in the TFA from lambs born to ewes with high CLA concentrations than from lambs born to ewes with low CLA concentrations in their milk fat. A 100g portion of lamb containing 2-4% lipid could contribute 2-5% of the estimated 750mg DRI of CLA for humans. However, if dietary TVA was assumed to be equivalent to CLA, then lamb could contribute 13-15% of the DRI. We conclude that lamb can provide a significant proportion of the DRI for CLA for humans and there is scope for farmers to further increasing the CLA and TVA content of beef and lamb.

Designing pastures for modern deer farming systems - Moloney S (Proceedings of the New Zealand Society of Animal Production, 2003)
Following on from definitive measurements on deer preferences to pasture species by Hunt & Hay in the late 1980’s, this paper provides some practical guidelines for how forage programmes can be set up in NZ deer farming systems. These programmes take into account the highly selective nature of NZ red deer, their strong preference for herbs and legumes well ahead of grasses. Three groups of pastures are put forward for use in integrated breeding and finishing deer systems. Group I are general purpose pastures, based on perennial grass species but include desirable herb and legume species. Within this group key selection criteria such as ryegrass heading date, endophyte type andploidy level are discussed. Group II pastures are built around the high performance characteristics of hybrid ryegrases including high soluble carbohydrate levels and cool-season yield, while still incorporating important legume and herb contributions. This group is considered strategically important in meeting the rapid growth demand of weaners in both the autumn and early-spring. Group III are specialist pastures based soley on herb and legume species. Collectively they are characterized by high animal VFI and performance, strong dietary preference by deer and winter dormancy. Their use for enhanced hind lactation and fawn growth rates, and mid-spring weaner growth is discussed. Pasture groups replacement rates, proportions within a whole farm system and some key establishment and management considerations are also addressed.

Development of a technique to evaluate the role of elevated maternal thyroid hormone concentrations in the birthweight response to mid-pregnancy shearing. - Kenyon PR; Parkinson TJ; Revell DK; Morris ST; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 2003)
Several studies have shown that lambs born to mid-pregnancy shorn ewes are heavier at birth than those born to unshorn ewes (Morris et al. 2000, Kenyon et al. 2002a,b) but, the mechanism responsible has not been identified. Morris et al. (2000) observed elevated maternal triiodothyronine (T3) concentrations over a 20-day period after shearing at mid-pregnancy in both single- and twin-bearing ewes and subsequently found an increased birthweight in the singletons. Symonds et al. (1989) also reported maternal T3 and T4 concentrations to be higher in pregnancy-shorn housed ewes although, an altered birthweight was not reported.

Diet and genotype affect feeding behaviour of Holstein-Friesian dairy cows during late lactation - Thorne PL; Jago JG; Kolver ES; Roche JR (Proceedings of the New Zealand Society of Animal Production, 2003)
Ingestive behaviour of New Zealand (NZ) and overseas (OS) Holstein-Friesian (HF) dairy cows grazing pasture only or fed a total mixed ration (TMR) was observed in late lactation. Data from visual observations every 10 minutes over a 48-h period were used to evaluate differences in time spent feeding, ruminating, standing and lying. OS HF and cows fed TMR had greater dry matter intakes (DMI) than their respective comparisons. Cows grazing pasture spent more time feeding, less time ruminating, less time standing and the same time lying, compared to cows fed TMR. OS HF spent less time feeding, the same time ruminating, the same time standing, and more time lying compared to NZ HF. When expressed in terms of DMI, OS HF took less time to consume a kg of DM, and spent less time ruminating each kg of DM compared to NZ HF, irrespective of diet. A genotype x diet interaction was observed for time spent standing, with NZ HF spending more time standing when fed TMR, but standing for a similar time as OS HF when grazing. These results suggest feeding and grazing behaviour differences between HF cows of differing genotype, but similar breeding worth.

Diet and genotype affect milk lactoferrin concentrations in late lactation - Turner S-A; Williamson JH; Thomson NA; Roche JR; Kolver ES (Proceedings of the New Zealand Society of Animal Production, 2003)
Although lactoferrin (Lf) is a valued milk protein, little information is available on factors that affect its concentration in milk. Milk samples were collected during late lactation to determine if diet or cow genotype affected the concentration and yield of Lf in bovine milk. Holstein-Friesian (HF) cows (n=52) of either overseas (OS) or New Zealand (NZ) ancestry were fed either an all-pasture diet or a total mixed ration (TMR). Milk samples were collected from each cow during an AM milking in early March and late April. NZHF had a higher (P<0.05) Lf concentration than OSHF even though they produced less (P<0.05) milk. Genotype did not affect Lf yield, somatic cell count or the proportion of bacteriologically negative quarters. The Lf concentration in the milk of cows fed TMR was higher (P<0.05) than cows grazing pasture in April but not in March. Cows fed TMR also produced more (P<0.05) milk and a greater (P<0.001) yield of Lf than cows grazing pasture. Diet did not affect SCC, however only cows fed TMR had any bacteriologically positive quarters. A positive within-cow correlation (P<0.001) was found between Lf and SCC. The effect of diet on the concentration of Lf in milk requires further investigation. The genotype results suggest that NZHF have higher concentrations of Lf in milk than OSHF. Naturally high concentrations allow improved extraction efficiencies of Lf during processing.

Diurnal variation in blood plasma metabolites and insulin of lactating dairy cows grazing pasture and supplemented with a high-lipid supplement either once or twice a day - Thomson NA; Singh K; Kay JK (Proceedings of the New Zealand Society of Animal Production, 2003)
The experiment determined the diurnal variation of a blood plasma hormone and three metabolites (insulin, glucose, NEFA and triglyceride) and how these varied with different frequencies of supplementary feeding. Twenty-four cows in early lactation (DIM 81 ± 20) were divided randomly into three treatments; grazed pasture only and pasture supplemented with 2 kg/cow/day of ruminally protected oilseed supplement (metabolisable energy 19 MJ/kg DM) either once a day after morning milking or twice a day after morning and afternoon milking. On day 12 of the experiment, 12 cows (4 cows/treatment) were jugular catheterised and commencing at 1600 h, blood sampled at 2-hourly intervals for 24 h. This protocol was repeated for the remaining 12 cows on day 13 Concentrations of the selected blood plasma hormone and metabolites varied diurnally (P<0.001). The difference between the average peak and nadir concentrations over the 24 hours were 54%, 66%, 224% and 63% for plasma insulin, glucose, NEFA and triglyceride respectively. Feeding the lipid supplement increased blood plasma NEFA (P<0.01), and triglycerides (P<0.001) but had no effect on insulin, or glucose concentrations. Frequency of supplementary feeding influenced (P<0.05) the diurnal variation of NEFA but not, insulin, glucose, or triglyceride. Concentrations of NEFA, glucose, and triglyceride were variable between 0600 h and 1000 h and stabilised between 1600 h to 2000 h. Plasma insulin concentrations were low and stable between 0400 h to 0800 h. Consideration of diurnal variation and the stability of the blood plasma components measured led to the recommendation that the best time to blood sample for insulin is between 0400 - 0800 h and for glucose, NEFA, and triglyceride, between 1600 2000h.

Dominance effects on the time budget and milking behaviour of cows managed on pasture and milked in an automated milking system - Jago J; Jackson A; Woolford M (Proceedings of the New Zealand Society of Animal Production, 2003)
The influence of social hierarchy on the behaviour of a herd of 41 cows milked in an automated milking system (AMS) was studied under conditions of free or no access to water at pasture. In phase 1 (P1) water was available within a central collection area (CCA) in the centre of the farm from which return to pasture was via the AMS. In phase 2 (P2), water was available at pasture in addition to the CCA. The time budget for activity (grazing, standing, lying or walking) and location (paddock, CCA entrance race, exit race or waiting yard) was determined over 2x24h in each of P1 & P2. Dominance values (DV) were calculated and cows classified as high, middle or low ranking. In P1 & P2, DV was positively related to the number of milking visits to the AMS. In P1, 83.4% of all drinking occurred in the CCA compared with 14.2% in P2. Social rank had no effect on time budget in P1, however, in P2, DV influenced waiting times with lower ranking cows spending a greater proportion of time waiting before entering the AMS. The results show that social rank affects the number of visits to the AMS and yard waiting times but has little effect on the activity time budget of cows milked in a AMS.

Effect of genetic merit on the estimated partitioning of energy towards milk production or liveweight gain by Jersey cows grazing on pasture - Bryant JR; Lopez-Villalobos N; Holmes CW; Pitman GD; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 2003)
Data from the 1999/2000 season of the Stratford demonstration farm stocking rate trial was used to estimate metabolisable energy intakes (MEI) and the amount of metabolisable energy (ME) partitioned into milk, maintenance and liveweight (Lwt) changes of Jersey cows of either high genetic merit (HGM) (average milksolids breeding value of 28 kg) or low genetic merit (LGM) (average milksolids breeding value of 11kg). Least-square mean yields for HGM and LGM cows were 327 and 289 kg of milksolids per cow respectively. HGM cows partitioned a significantly higher proportion of MEI into milk than LGM cows in early (0.67 vs 0.63; P<0.01), peak (0.59 vs 0.57; P<0.05), mid (0.58 vs 0.56; P<0.01) and late lactation (0.54 vs 0.51; P<0.01) (HGM vs LGM respectively). In early lactation, HGM cows utilised more body reserves for milk production (-0.05 vs -0.01, for HGM and LGM respectively). These results confirm that HGM cows partition more ME to milk throughout lactation than LGM animals for a range of feeding levels on grazed pasture. The greatest difference occurred in early lactation, resulting in increased body tissue loss and a greater negative energy balance in HGM cows.

The effect of hybridisation on venison production - Nicol AM; Judson HG; Taylor AW (Proceedings of the New Zealand Society of Animal Production, 2003)
Elk x red deer `hybrids` or technically, crossbreds make a major contribution to New Zealand venison production. Probably over half of the venison produced from young animals (< 2 yrs of age) contains some proportion of elk genes. Elk, and the numerically more significant ‘hybrid’ (50-88% elk), stags are used as terminal sires over red deer hinds to produce faster growing progeny. The main benefit of the faster liveweight gain is that a high proportion of hybrids reach slaughter live weight (100 kg+) at around 1 year of age to capture current market premiums. Due to the lesser sexual dimorphism of elk than red deer, hybrid females show a greater increase in liveweight gain and weight-for-age over their red deer counterparts than do males. Most of the advantage in yearling weight of hybrids has accrued by weaning and is, thus, captured by the breeder. The absolute and proportional increase in liveweight of hybrids is greater when live weight gain is high (in autumn and spring and under generous feeding levels) and production systems utilising hybrids must recognise this. The metabolisable energy (ME) requirement for maintenance per unit metabolic weight seems to be higher (20%) for young hybrids than for red deer, although in contrast, the ME cost of liveweight gain may be slightly lower. Small differences in body composition also exist. However, neither of these necessitates major modification to venison production systems. The widespread use of `hybrid` stags in the New Zealand deer industry has increased the biological efficiency and economic returns to venison production, although increased liveweight gain and weight-for-age must be offset against a somewhat lower reproductive rate in red deer hinds joined with elk or hybrid stags. Hybridisation has also increased the demand for red deer replacement hinds and raised doubts about the wisdom of retaining hybrid hinds as breeding females.

The effect of sward height on twin and triplet lamb birth weights and survival rates to weaning - Morris ST; Kenyon PR; Burnham DL; Everett-Hincks JM (Proceedings of the New Zealand Society of Animal Production, 2003)
The differential allocation of pasture between ewes of different bearing/rearing ranks requires a knowledge of the relationship between herbage allowance, intake and production. Few experiments have been conducted in which responses to different pasture allowances have been examined for triplet-bearing/rearing ewes, particularly under continuous stocking management. Published feed requirements for ewes rearing triplets have often been extrapolated from those defined for twin-rearing ewes (Geenty & Rattray 1987). The sward surface guidelines for feeding single- and twin-bearing ewes have been published and researched under New Zealand conditions (Parker & McCutcheon 1992; Morris et al., 1993a, 1993b; Morris et al., 1994). There is anecdotal evidence for varying lambing performance and lamb growth rates for triplet-bearing/rearing ewes under pastoral grazing conditions. The national average lambing percentage is increasing to beyond 120% (MWIES 2002). The proportion of triplets in flocks lambing above 150% increases at the expense of single-born lambs (Amer et al., 1999). The aim of the research communicated in this paper was to compare ewe and lamb performance in twin- and triplet-bearing/rearing ewes offered various sward height allowances.

Effect of withholding anthelmintic treatment on autumn growth and internal parasitism of weaner deer grazing perennial ryegrass-based pasture or chicory - Hoskin SO; Pomroy WR; Reijrink I; Wilson PR; Barry TN (Proceedings of the New Zealand Society of Animal Production, 2003)
Sixty-eight weaner deer were allocated to grazing perennial ryegrass-based pasture or chicory from 18 March to 20 May 2002, and within these groups were either regularly treated four-weekly with anthelmintic or treatment was withheld until weight loss or clinical signs of parasitism such as coughing was observed (trigger treatment). Liveweight gain was monitored fortnightly. Five sentinel deer from each of the four groups were slaughtered for nematode counts on 20 May. Deer grazing chicory grew faster than deer gazing pasture (P<0.001). Thirty five percent of trigger-treated deer grazing pasture required treatment for clinical parasitism, but no anthelmintic was required for trigger-treated deer grazing chicory. There was no effect of anthelmintic treatment on average autumn growth of deer grazing chicory, but trigger-treated deer grazing pasture grew at half the rate of regularly treated deer (P<0.01). Deer grazing chicory and treated four-weekly with anthelmintic grew 1.5x faster than deer grazing pasture and treated four-weekly with anthelmintic (P<0.05). This difference in growth of deer grazing chicory and pasture increased to 2.9x when comparing triggertreated deer grazing the two forages (P<0.01). Sentinel trigger-treated deer grazing chicory had half the lungworm population of deer grazing pasture (P=0.13) and 18% fewer gastrointestinal nematodes (P=0.06). This study shows that grazing young farmed deer on chicory during autumn can increase their resilience to internal parasitism, reducing anthelmintic use whilst increasing deer growth.

Effects of different forages on phenol and methylphenol formation in the rumen of sheep - Fraser K; Lane GA; Schreurs NM; Tavendale MH; McNabb WC; Marotti DM (Proceedings of the New Zealand Society of Animal Production, 2003)
Rumen concentrations of the undesirable phenol flavour compounds 4-methylphenol, 3-methylphenol, and phenol, were measured in pooled samples from six rumen-fistulated Romney wethers. Samples were collected at approximately 1 hr intervals for 8 hr after feeding white clover (WC), perennial ryegrass (PRG), or Lotus corniculatus (LC). For all three phenols, the time-course curves for the rumen concentration differed significantly between the three diets (P<0.001) with wide differences in maximum concentrations. For 4-methylphenol, concentrations normalised to crude protein intake (CPI) were very similar. Concentrations of phenol normalised to CPI were very similar for PRG and WC diets but much lower for the LC diet. No 3-methylphenol was detected in the rumen of WC-fed animals. For animals fed the PRG and LC diets, concentrations of 3-methylphenol normalised to acid detergent fibre intake were similar. Differences were also observed in the time to maximum concentration after the commencement of feeding, which was much shorter for 4-methylphenol and phenol (2-3.5 hr) than for 3-methylphenol (6 hr). This study established that feeding different forages resulted in differences in phenol metabolism in the rumen, and provides evidence that 4-methylphenol and 3-methylphenol derive from different dietary sources.

The effects of insulin on the milk production of pasture-fed Jersey cows - Back PJ; MacKenzie DDS; Davis SR; Harris PM; Lee J (Proceedings of the New Zealand Society of Animal Production, 2003)
The aim of this experiment was to determine the effects of insulin on milk protein production in lactating, pasturefed dairy cows. Five lactating rumen-fistulated Jersey cows were subjected to a hyperinsulinaemic euglycaemic clamp (HEC) with and without an abomasal infusion of casein (310g/d) in a two period cross-over design experiment. The HEC significantly reduced milk yield in the control cows compared to casein-infused cows (9.9 ± 0.5 vs 13.2 ± 0.5 kg/d, P<0.001). Milk protein yield was significantly higher in the casein-infused cows compared to the control cows (482 ± 16 vs 421 ± 16 g/d, P<0.05). The HEC significantly reduced milk protein yield in the control cows compared to casein-infused cows (311 ± 16 vs 459 ± 16 g/d, P<0.001). The use of the HEC technique in pasture-fed cows did not result in the milk protein response reported in concentrate-fed cows.

Effects of intensive dairy and deer farms on streams and trout fisheries - Rodway M (Proceedings of the New Zealand Society of Animal Production, 2003)
Many streams flowing through agricultural landscapes in New Zealand have poor water quality and biotic indicators. Loss of riparian zone function through vegetation removal and stock access cause changes. Farms where large numbers of cattle and red deer have access to streams result in degraded streams. Restoration of riparian zones and exclusion of stock from streams results in improvements but careful land management is also needed to ensure water quality and instream life is protected.

Empirical assessment of the CNCPS model to predict performance of dairy cows fed pasture with silage supplements - Chaves AV; Brookes IM; Burke JL; Waghorn GC; Woodward SL (Proceedings of the New Zealand Society of Animal Production, 2003)
The goal of this work was to determine the accuracy and utility of the Cornell Net Carbohydrate and Protein System (CNCPS) model to predict milk production from diets based on pasture and forage supplements. Data were obtained from studies in which pasture was complemented with contrasting silages including maize, pasture, sulla, lotus and forage mixtures, comprising 30-40% of dry matter intake (DMI). Twelve diets were used in this evaluation. DMI, live weight (LW), days in milk, and diet composition were determined during the trials and used as inputs in the model. Across all diets, a significant (P<0.01) relationship existed between predicted and actual values for DMI (r2=0.63), milk yield (r2=0.64) and LW change (r2=0.57) but there were still large unexplained sources of variation and the slopes of the regression lines were significantly (P<0.01) different than 1. No significant mean bias was observed for any of the variables, but the slope of residual differences against predicted values was significantly different from zero (P<0.01 for milk yield and LW change; P<0.06 for DMI). The results indicate a satisfactory prediction of milk production when cows are neither gaining nor losing weight, but that a systematic bias exists probably because of the CNCPS model’s failure to account for nutrient partitioning.

Evidence of a genotype by feeding level interaction in grazing Holstein-Friesian dairy cattle at different stocking rates - Bryant JR; Holmes CW; Lopez-Villalobos N; MacDonald KA; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 2003)
Lactation yields and estimated breeding values (EBVs) for protein, fat and milk were obtained for individual cows in a farmlet trial carried out at Dexcel in Hamilton, using Holstein-Friesian cows, to test for the existence of a genotype by environment interaction across the range of feeding levels, and EBVs typically found on New Zealand pasturebased dairy farms. At very low levels of feeding, with yields of 267 - 307 kg milksolids per cow (kg MS/cow), regression coefficients of lactation yield on EBVs were not significantly different from the expected value of 1. At high levels of feeding, with yields of 383 - 411 kg MS/cow, most of the regression coefficients for yields of protein, fat and milk on EBVs were significantly greater than 1. The results of this study show that at low levels of feeding the actual differences in production between cows, which differ in EBVs correspond to the actual differences in EBVs, whereas at high levels of feeding the difference in milk yields between genetic groups are greater than the difference in EBVs. This constitutes a form of genotype x environment interaction, in which genotype is measured as breeding values, and has important practical and economic implications for dairy farms, and for the expected value of genetic improvements.

Exploring the potential applications of advanced reproductive technologies in deer farming - Wells DN; Berg DK (Proceedings of the New Zealand Society of Animal Production, 2003)
Advanced reproductive technologies include in vitro embryo production, cloning and genetic modification. However, only the former has been developed in deer. Considerable experimentation is required to develop cloning and transgenesis which is only justified if the deer industry foresees future potential and if animal welfare and public acceptance issues are addressed. Efficient in vitro embryo production and cloning potentially enables rapid dissemination of desired genotypes but relies on accurate identification of genetically superior individuals, which is limiting. In vitro embryo production with oocytes from elite females increases genetic gain and is further enhanced with pre-pubertal animals by shortening generation interval. Utilising sexed sperm to pre-determine gender increases reproductive efficiency. Cloning by nuclear transfer pre-determines the genotype of the animal and could effectively produce cloned stags from progenytested sires for natural breeding. Transgenesis introduces novel genetic modifications into the genome but is limited by the present poor understanding of which genes to manipulate to enhance desirable traits. The advancement of animal genomics will identify both individual genes and entire genotypes to multiply. Nevertheless, these technologies are considerably more difficult to cost-effectively implement than even poorly adopted artificial insemination in an extensive deer industry and will only be relevant for specialised markets.

Forage intake and feed conversion efficiency in high-producing dairy herds in New Zealand: a case study - Salles PV; Matthews PNP; Holmes CW; Hodgson J; Shadbolt NM (Proceedings of the New Zealand Society of Animal Production, 2003)
In 1998 a three-year dairy farm monitoring programme was established on twelve dairy farms in the southern North Island of New Zealand where production policy had changed from a focus on high production per hectare through high stocking rates to a strategy based on high production per hectare through enhanced production per cow. Results of the third year for nine of these farms revealed a range of apparent feed intake (50,669 - 70,135 MJ ME/cow/year), milksolids production (372 - 432 kg MS/cow/year) and feed conversion efficiency (6.0 - 7.4 g MS/MJ ME intake). There was a significant positive correlation (R2= 0.57, P<0.05) between annual apparent ME intake per cow and annual milksolids production per cow, with a regression coefficient equivalent to 2.5 g MS produced per MJ ME intake, but a significant negative correlation (R2 = 0.80, P<0.01) between ME intake and feed conversion efficiency. The apparent ME intakes measured were 21% and 8% higher than theoretical requirements for the farms with higher and lower (compared to each other) milksolids yield values, respectively. This suggests that the high-performance farms may have wasted more feed. Implications for management of feed resources to optimise efficiency in high-production systems are discussed.

Frequency of mastitis and variation in somatic cell counts throughout the lactation in cows managed organically or conventionally; Year 1 - Lopez-Villalobos N; Scott J; Smith Z; Holmes CW; Shadbolt NM; Harvey TG (Proceedings of the New Zealand Society of Animal Production, 2003)
Interest in organic milk production is growing in New Zealand. At present milk is being collected from 13 organically certified farms in the North Island and 66 farms have been identified as either certified organic or interested in converting from conventional production (Stevenson, 2002). Massey University started a trial on August 2001 to monitor the difference between organic and conventional dairy farming systems, and to provide New Zealand dairy farmers with proven information on differences between the two systems. A key focus of the organic farming system is the maintenance of health and well-being of cows in the herd, without the routine use of conventional methods (e.g., antibiotics). Mastitis has been recognised as the main disease problem. The objective of this report is to present results on the variation in somatic cell counts (SCC), frequency of clinical mastitis (CM) and frequency of acute levels of SCC of cows managed according to either organic or conventional farming practices for the season 2001 to 2002, the first year after the change to organic farming.

Genetic and environmental parameters for lambing behaviour in Merino lines divergently selected for ewe multiple rearing ability - Cloete SWP; Van Wyk JB; Scholtz AJ; Gilmour AR (Proceedings of the New Zealand Society of Animal Production, 2003)
Data were recorded for lambing behaviour of approximately 1000 Merino ewes lambing over a 10-year interval from 1993 to 2002. The resource population was divergently selected from the same base population since 1986, either for (H line) or against (L line) maternal multiple rearing ability. Line differences (P < 0.05) favoured H line ewes for length of parturition and maternal cooperation score. Heritability was estimated at 0.17 ± 0.04 for length of parturition, 0.11 ± 0.04 for maternal cooperation score and 0.20 ± 0.04 for the interval ewes remained on or near to the birth site. A small service sire effect for length of parturition in ewes amounted to 0.03 ± 0.02. Maternal cooperation score was genetically related to the time spent on or near to the birth site (0.53 ± 0.18). Genetic divergence between lines was detected in all three traits. These results and the obtained parameter estimates indicate that selection for improved multiple rearing ability was feasible in paddock-reared sheep flocks.

Genetic improvement of red deer - Archer JA (Proceedings of the New Zealand Society of Animal Production, 2003)
Deer breeding has made significant progress in a relatively short time. However, opportunities exist to make further advances in several areas. Development and implementation of across-herd breeding value analyses could significantly benefit the deer industry through providing opportunity to accelerate rates of genetic gain, and by providing commercial stag purchasers with objective information on which to base stag selection. This will require the development of standard recording protocols and a central performance database, but the technical issues surrounding this are solvable and suitable models exist in other livestock industries. With changing composition of industry returns, deer farmers and breeders might re-evaluate whether they are best served by selection for specialist velvet and venison lines, or whether a dual-purpose animal remains the best option. There may also be value in broadening the traits objectively described to include aspects of venison production other than growth.

Genetics of lamb survival - Amer PR; Jopson NB (Proceedings of the New Zealand Society of Animal Production, 2003)
Data from seven commercial New Zealand sheep flocks were analysed to quantify the extent to which lamb survival in New Zealand sheep is influenced by genetic factors. Estimates of direct and maternal genetic variance components, and the effects of inbreeding in either the lamb or the dam on lamb survival, were found to vary significantly across flocks. Direct heritability estimates ranged from 0.008 to 0.070, while maternal heritability estimates ranged from 0.002 to 0.075. Inbreeding in the lamb showed a statistically significant (P<0.05) effect on survival in three of the seven flocks, ranging in value from -0.17 to -0.29% reduction in lamb survival for a 1% increase in inbreeding coefficient. Inbreeding of the lamb’s dam had a statistically significant effect (P<0.05) on survival in two of the seven flocks, taking values of -0.32 to -0.71% reduction in lamb survival for a 1% increase in the dam’s inbreeding coefficient. It is recommended that lamb survival records be transformed to a constant variance within flock and year prior to estimation of breeding values, but that no transformation to either a logit or probit scale within the statistical analysis is required. Inbreeding coefficients for both the lamb and the lamb’s dam should be included as linear covariates in the mixedmodel analysis of lamb survival breeding values.

Heritability of Johne's disease and survival data from Romney and Merino sheep - Hickey SM; Morris CA; Dobbie JL; Lake DE (Proceedings of the New Zealand Society of Animal Production, 2003)
Eight years of health records for ovine Johne’s disease (OJD) from a long-term breeding trial with Romneys and Merinos at AgResearch`s Tokanui Station were analysed, to study the quantitative genetics of animal resistance/susceptibility to OJD. Necropsy records were used in preference to serology to determine OJD status. A total of 2348 Romney and 1297 `Merino` ewe records (5 groups: two purebred Merino groups (Australian imported superfine and NZ purebred Merino), two Merino x Romney halfbred groups and a superfine Merino back-cross) were analysed for OJD and survival, comprising animals born between 1971 and 1978. Few males were retained past two years of age, so disease and survival data on males were excluded. Romney ewes had a mean lifetime incidence of OJD of 3.49% (range, by year of birth, 2.11 to 5.00%), whilst the mean for Merino ewes was 4.78% (range, by year of birth, 0.0 to 7.74%). The breed contrast approached significance (P<0.051). The mean age at OJD incidence was 3.44 ± 0.09 years for Romneys, compared with a mean age for surviving females in the sample of 5.04 ± 0.02 years (P<0.001). Corresponding means for Merinos were 3.38 ± 0.13 and 5.00 ± 0.04 years, respectively (P<0.001). The heritability of lifetime incidence of OJD, considered as a binomial trait and using animal-model restricted maximum likelihood methods, was estimated as 0.07 ± 0.14 and 0.18 ± 0.11 for Romneys and Merinos respectively, giving an overall value (pooled within breeds) of 0.14 ± 0.09. Adjusting for Merino group in the relationship matrix (rather than as a fixed effect) led to a heritability for Merinos of 0.24 ± 0.09. These estimates may be biased upwards by `vertical transmission` of OJD organisms from dam to offspring. The heritability of age at death/culling had values of 0.11 ± 0.04 and 0.16 ± 0.05 for Romneys and Merinos respectively, with a pooled value of 0.13 ± 0.03. With the low heritability estimates for OJD in Romneys it is concluded that traditional breeding methods to reduce the incidence would be slow or unsuccessful; however, for Merinos, selection could begin to reduce the incidence, but ranking later generations may become difficult.

Impact of diseases on the NZ deer industry - Mackintosh CG; Wilson PR (Proceedings of the New Zealand Society of Animal Production, 2003)
The financial impact of a range of clinical and subclinical diseases, and mortalities on deer farms is difficult to assess because there are insufficient accurate survey data of their prevalence, causes or production losses on a national basis. However, estimates suggest that clinical disease and current disease control measures may cost the deer industry in excess of $29 million per annum currently, and it may be speculated that at least that amount may be lost due to loss of production from subclinical diseases, resulting in potential costs and losses approaching $60 million per annum. Application of existing knowledge of disease control and prevention on individual farms would significantly reduce this wastage immediately. In addition, investment to improve technology for disease diagnosis, control, prevention and/or eradication, along with adoption of that technology should yield significant dividends for the deer industry.

Interaction of gastro-intestinal nematodes and calf weaning management on beef cattle growth - Boom CJ; Sheath GW; Vlassoff A (Proceedings of the New Zealand Society of Animal Production, 2003)
An experiment was undertaken to study the effects of calf weaning management on growth rates and susceptibility to gastro-intestinal nematodes. Treatments were: weaned at 6 months (of age) and normal anthelmintic use; weaned at 6 months and no anthelmintics; weaned at 6 months yet grazed with dam until 9 months and no anthelmintics; weaned at 9 months and no anthelmintics. At 9 months of age, calf live weights for the four treatments were: 264, 253, 265 and 308 kg respectively (SED = 2.0). Faecal-egg counts and serum pepsinogen levels were not affected by weaning date. Milk consumption by the later weaned calves was 4.2 kg/day, resulting in herbage intakes being 25% lower than calves in other treatments (P<0.01). When suckling calves to 9 months of age, the cost of this milk production to the cow was 26 kg live weight (SED = 6.3). Later weaning gave a substantial increase in calf live weight (P<0.001), which can be attributed to milk consumption. Faecal-egg counts and serum pepsinogen levels indicated that milk consumption did not have a direct effect on gastro-intestinal nematode burdens.

Lack of genetic association of markers near the leptin gene with carcass fat content in Coopworth sheep lines selected for and against fatness - Campbell AW; Broad TE; Jopson NB; Burkin HR; Dodds KG; Veenvliet BA; Bain WE (Proceedings of the New Zealand Society of Animal Production, 2003)
Leptin is an important hormone in controlling food intake and energy expenditure in mammalian species. The present study evaluated levels of serum leptin in Coopworth sheep selected for and against subcutaneous fat depth for 10 generations. Significant differences in serum leptin concentrations were found between fat and lean sheep (P<0.05) and between male and female sheep (P<0.01). Serum leptin concentration was positively correlated with carcass fatness and there was a clear relationship between mean progeny serum leptin concentrations and the breeding value for fat. Serum leptin concentrations were greater (P<0.05) in lambs selected from the fat line (2.69ng/ml) than in lambs selected from the lean line (2.18ng/ml). A microsatellite marker, OarCP26, already mapped on sheep chromosome 4 (OAR4) was located in a sheep yeast artificial chromosome (YAC) clone that was positive for the leptin gene (LEP). This confirmed the independent assignment of LEP, mapped using a sheep cell hybrid panel, to OAR4. No significant differences in the allele frequencies of OarCP26 and two other flanking markers (TGLA116 and OarHH335) were detected in the lean and fat selection lines suggesting genes other than leptin are causing the differences in fat between the lean and fat Coopworth lines.

Lessons to NZ sheep breeders from other species and other countries - Piper LR; Banks R (Proceedings of the New Zealand Society of Animal Production, 2003)
The SIL system for genetic improvement of productivity in the New Zealand sheep flock has been reviewed. It is technically well designed, and provides first rate genetic information to a range of breeder users. However, the availability of such a system for performance recording and genetic evaluation does not guarantee that it will be fully utilised by industry to achieve high rates of genetic gain for economically important breeding objectives. Ways of maximizing participation by the nucleus sector and of maximising the choice among genetically comparable rams for the commercial sector need to be pursued.

LIC Lecture - The development of environmental best practices for intensive dairying - Monaghan RM; Morton JD; McDowell RJ; Drewry JJ; Thorrold BS (Proceedings of the New Zealand Society of Animal Production, 2003)
Research since 1995 has focused on soil, fertiliser and animal management factors affecting soil and water quality in intensive dairy systems on imperfectly to poorly drained soils in Southland and Otago. Derived from this on-farm research, best practice for effluent, fertiliser and soil management to ensure that required environmental standards are attained, is outlined.

A long-acting injectable Se/Vitamin B12 product to prevent Se and Co deficiency in lambs - Grace ND; Knowles SO (Proceedings of the New Zealand Society of Animal Production, 2003)
The efficacy of a novel injectable formulation containing barium selenate (BaSeO4) and microencapsulated Vitamin B12 was evaluated in groups of lambs (n=10) over 246 days in terms of changes in blood Se and serum Vitamin B12 concentrations as well as growth responses. Mean blood Se and serum Vitamin B12 concentrations of the untreated control lambs were 125 ± 9 nmol/L and 508 ± 21 pmol/L, respectively. The formulation increased blood Se to 2100 nmol/L at day 64 before decreasing to 761 nmol/L at day 246. Likewise, serum Vitamin B12 reached a peak of 1950 pmol/L at day 31 before decreasing to 577 pmol/L at day 246. The treatment significantly increased (P<0.05) daily weight gains from 125 ± 4 to 136 ± 4 g/day. An injectable Se/Vitamin B12 product containing 12 mg Se as BaSeO4 and 3 mg Vitamin B12 per dose administered at docking was effective in increasing and maintaining the Se and Vitamin B12 status of lambs for at least 246 days.

Maintaining product quality from the farm gate to the processing facility - Pollard JC; Littlejohn RP; Scobie DR; Pearse AJT; Stevenson-Barry JM (Proceedings of the New Zealand Society of Animal Production, 2003)
There is substantial evidence that pre-slaughter events (mustering and holding in yards, transport, lairage and preslaughter handling) have negative effects on product quality through bruising, hide damage and muscle pH. To minimise these negative effects, use of deer-specific, good stock handling procedures and appropriately designed facilities are essential. The duration of pre-slaughter events and human presence should be minimised. Yard pens should be appropriately sized, dark, quiet, and deer should be kept in familiar groups. Adherence to existing guidelines for transport, careful driving, and avoiding transport during hot weather are desirable. Showering deer upon arrival at the processing plant plus provision of water in lairage pens probably prevents dehydration. Conversely, showering under some conditions may add to stress and bruising damage in lairage. Research proposed to improve pre-slaughter handling includes taming and selection for tractable deer, definition of appropriate handling techniques and improved facility designs. Further work is also required to identify optimal practices for lairage, showering, washing and feeding.

Making better use of the SIL genetic engine - Newman S-AN (Proceedings of the New Zealand Society of Animal Production, 2003)
Developments in genetic evaluation techniques used in the SIL genetic engine have increased the accuracy with which estimated breeding values are calculated and have provided maternal breeding values for growth and survival traits. Although these will assist progressive breeders, a considerable number of breeders would gain greater benefits from improvements in data recording techniques to more fully utilise the potential of the SIL genetic engine to identify genetically superior animals. In particular, reproductive and survival data are often recorded less than optimally. Ewes culled at pregnancy scanning, barren ewes, lambs born dead and lamb deaths from birth to weaning require particular attention.

Metabolic changes in ewes shorn during mid-pregnancy - Sherlock RG; Kenyon PR; Morris ST; Parkinson TJ (Proceedings of the New Zealand Society of Animal Production, 2003)
Previous work has shown that, under appropriate circumstances, mid-pregnancy shearing results in an increase of both the birth and weaning weights of multiple-born lambs. However, the physiological mechanisms for this response are poorly understood. This paper attempts to clarify the link between mid-pregnancy shearing and heavier lamb weights by investigating the metabolic changes that occur in ewes that are shorn in mid-pregnancy. Twenty-four twin-bearing ewes were assigned to one of two treatment groups; mid-pregnancy shorn (70 days after the mid-point of mating: P70) or unshorn. Groups were balanced for ewe age and weight. Blood samples were collected from all animals on days P53, P69, P81, P84, P90, P109 and P130, for measurement of concentrations of triiodothyronine (T3), thyroxine (T4), cortisol, glucose, non-esterified fatty acids (NEFA) and beta-hydroxybutyrate. Lamb birth weight, girth and crown-rump length (CRL) measurements were collected within 24 hrs of birth. Lambs were weighed at weaning. Mid-pregnancy shearing increased lamb birth weights and girths by 0.43 kg (P<0.05) and 2.18 cm (P<0.05) respectively although these differences were not significant once adjusted for date of birth. There was no effect on CRL. Plasma concentrations of T3 and T4 were significantly higher in mid-pregnancy-shorn ewes relative to unshorn ewes at both P81 (P<0.01) and P84 (P<0.01 and P<0.05 respectively) and T4 concentrations tended to be higher at P90 (P<0.10). There was a significant effect of shearing treatment at P81 on plasma NEFA concentrations (P<0.05). There were no significant post-shearing differences in mean cortisol, glucose or beta-hydroxybutyrate concentrations. The study proposes that the most likely mechanism by which mid-pregnancy results in higher lamb birth weights is by increasing maternal thyroid hormone concentrations, resulting in an increase in fat mobilisation causing increased NEFA concentrations in the maternal blood supply, which in turn improves placental nutrition and, thus, lamb birth weight.

Metabolic responses to glucose challenge in New Zealand and overseas Holstein-Friesian dairy cows - Chagas LM; Clark BA; Rhodes FM; Blache D; Kolver ES; Verkerk GA (Proceedings of the New Zealand Society of Animal Production, 2003)
North American and Dutch Holstein-Friesian (HF) cattle have undergone genetic selection for increased milk production, however, at the same time, reproductive efficiency has decreased. Overseas HF also have greater propensity to mobilise body reserves during early lactation than New Zealand HF cows. It is possible that reproductive differences are a consequence of metabolic and endocrine differences between the strains. This trial was designed to investigate effects of genotype and diet on endocrine response to a challenge of intravenous glucose in HF cows. Twenty-five HF cows of New Zealand (NZ; n=13) and Overseas (OS; n=12) origin, were fed either pasture (Grass; n=12) or a total mixed ration (TMR; n=13) in a 2x2 factorial design. At two weeks postpartum, they were challenged with 300mg of glucose/kg live weight. Data were analysed for effects of genotype and diet. Following glucose challenge, the NZ TMR cows had higher plasma insulin concentrations than the NZ Grass, resulting in a significant interaction between diet and genotype in the area under the response curve; but the OS groups had similar patterns. Mean plasma leptin concentration was higher in NZ TMR than in NZ Grass, OS TMR or OS Grass. Plasma concentrations of glucose and IGF-I were not affected by genotype or feed regime. These results demonstrated metabolic differences between the strains and also diets. A better understanding of the genetic and nutritional basis of hormonal regulation of nutrient partitioning will be important to develop nutritional strategies to meet the requirements of lactating cows with different genotypes, and to find ways to improve reproductive efficiency.

Methane and carbon emissions from conventional pasture and grain-based total mixed rations for dairying - van der Nagel LS; Waghorn GC; Forgie VE (Proceedings of the New Zealand Society of Animal Production, 2003)
Comparisons between cows grazing pasture or fed total mixed rations (TMR) show on average less milk production from pasture but a higher methane yield per milk or milksolids production from the pasture diet. The implication that TMR are associated with relatively lower greenhouse gas (GHG) emissions than pasture required an assessment of all production costs associated with both systems because TMR requires extensive cultivation and processing of grains and silages which form the bulk of the diet. A partial life cycle analysis of GHG (excluding nitrous oxides) was carried out for separate 250 cow herds located in Waikato (pastoral grazing) and Canterbury (cropping land for the TMR). This demonstrated much higher methane and carbon dioxide emissions, (kg CO2 equivalents/kg milk) from cows fed TMR (1.53) relative to pasture (0.84). The principal cause of the high value for TMR were carbon losses from soil cultivation which accounted for 64% of emissions, expressed as CO2 equivalents compared to 24% from pasture. Enteric methane accounted for 28% of GHG from TMR and 64% from pastoral systems. The remaining 8% and 12% from TMR and pastoral grazing respectively, were attributed to fertilisers, cultivation and processing.

Modelling optimum switch date from twice- to once-daily milking in dairy herds - Westbrooke VCF; Dooley AE; Vetharaniam I (Proceedings of the New Zealand Society of Animal Production, 2003)
The production of a dairy herd was simulated at two different stocking rates (3.4 cows/ha and 4.0 cows/ha) and two seasonal conditions (an average and a dry Waikato summer). Cows were milked twice-daily (TDM) for varying periods, before being switched to once-daily milking (ODM) for the remainder of the lactation. Switching from TDM to ODM during the milking season reduced the total production of the herd. With 3.4 cows/ha in an average summer, at a break-even value of labour of $100 /milking ($200 /milking) the optimum switch-over date was January 13 (October 21); a dry season brought forward this date by approximately two weeks. Increasing payout increased the break-even value of labour at a given switch-over date. Under a commonly used farmer industry guideline, break-even labour values under average (dry) conditions were $53.47 /milking ($61.47) for 3.4 cows/ha and $36.07 /milking ($33.98) at 4.0 cows/ha. A stocking rate of 4.0 cows/ha switching to ODM after peak production had a lower cash surplus than a 3.4 cows/ha stocking rate with TDM due to additional ($30,000) feed costs with the higher stocking rate. These results suggest a formal approach could be used to complement industry guidelines in deciding when to switch from TDM to ODM.

Optimising calf growth of red deer in summer and autumn - Stevens DR; Corson ID (Proceedings of the New Zealand Society of Animal Production, 2003)
The potential for red deer calves to grow is at its maximum during lactation and the early autumn before the first winter. Capturing this potential is one key to economic success in venison production. On-farm and experimental results have shown a wide range of live weight gains during these periods. Feed allowance during this time should ensure that residual pasture mass should not be below 1200-1500 kg DM/ha, while pasture allowance should be above 4 kg DM/d. Feed quality needs to be above 11 MJ ME/kg DM or a pasture should contain more than 70% green leaf. Poor liveweight gain in calves during late lactation and autumn delays subsequent slaughter and may lead to a substitution of weaners for hinds, decreasing the net productivity of a farming system. Strategies for improving both the amount and quality of feed on offer during summer and autumn include improved spring management, use of grasses with later flowering dates, increasing the use of specialist high-quality feeds such as red clover, chicory and lucerne, using management to increase white clover content and using brassicas or concentrate feeds if other options fail.

Postpartum anoestrous intervals and reproductive performance of three genotypes of Holstein-Friesian dairy cattle managed in a seasonal pasture-based dairy system. - McNaughton LR; Verkerk GA; Parkinson TJ; MacDonald KA; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2003)
An extended postpartum anovulatory interval (PPAI) is the major form of infertility in New Zealand (NZ) dairy cattle. Recently, Holstein cows, originating from North American genetic strains (Overseas; OS), have been widely used in NZ. Worldwide, there is concern over an apparent decline in the fertility of Holstein-Friesian dairy cattle. This study determined whether differences existed in PPAI, BCS and parameters of reproductive performance between NZ and OS Holstein-Friesians. One hundred and forty-six records from 88 NZ animals of high genetic merit for milk production (NZH), 81 records from 48 NZ animals of low genetic merit (NZL), and 137 records from 88 OS high genetic merit animals that calved in Years 1 (all two-year-olds) and 2 (two- and three-year-olds) were included. Over both years PPAI in two-year-olds were significantly shorter in OS (20 days shorter) and NZL (12 days shorter) than in NZH animals (P<0.05). Body condition score at calving, and BCS loss from calving to four weeks postpartum were not different between strains. In Year 1 of the study significantly more NZH than NZL or OS 2-year-olds were treated for anoestrus prior to the start of mating (P=0.001). Other measures of reproductive performance did not differ significantly between strains. The differences in PPAI require further investigation.

Postprandial indole and skatole formation in the rumen when feeding white clover, perennial ryegrass and Lotus corniculatus - Schreurs NM; Tavendale MH; Lane GA; Barry TN; Marotti DM; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2003)
In some international markets, meat and milk products from pasture-fed animals is associated with an undesirable pastoral flavour and odour. Sensory evaluation and chemical analysis of products has associated these flavours and odours with the presence of skatole and indole. Skatole and indole are formed in the rumen from the degradation of dietary protein. Condensed tannins (CT) have been shown to reduce protein degradation in the rumen and could reduce the formation of skatole and indole. This study investigated the concentrations of skatole and indole in the rumen of sheep after feeding white clover (WC), perennial ryegrass (PRG) and the CT forage, Lotus corniculatus (LC). Six rumen-fistulated Romney wethers were fed the cut forages and rumen contents sampled at intervals after the start of feeding. Feeding WC resulted in higher (P<0.05) peak concentrations of indole and skatole in the rumen per kilogram of crude protein eaten (CPI) compared to PRG and LC. There was a higher peak concentration of indole, but not skatole, in the rumen of sheep fed PRG compared to sheep fed LC (P<0.05). Feeding LC resulted in lower peak concentrations of skatole compared to feeding WC and lower peak concentrations of indole than when feeding WC or PRG. White clover in pastures may be a key factor of the high skatole and indole contents in meat and milk products obtained from pasture-based grazing systems. CT forages seem a likely solution to reducing ruminal skatole and indole formation.

Predicting Delta9-desaturase activity and the association with conjugated linoleic acid (CLA) concentration in bovine milk - Thomson NA; Chand A; Kay JK (Proceedings of the New Zealand Society of Animal Production, 2003)
The major source of cis-9, trans-11 conjugated linoleic acid (CLA) in bovine milk is from the post-ruminal conversion of trans-11 C18:1 (TVA) by D9-desaturase. Activity of D9-desaturase is predicted from the product/substrate ratios of fatty acids dependant on the enzyme. Data from three experiments was investigated. Cows selected for having soft or hard milk fat were fed ruminally protected oilseed in spring 1999, and autumn 2000 or crushed full-fat rapeseed in autumn 2001. Cows with harder milk fat had higher concentration of milk fat (P<0.001), and lower concentrations (P<0.001) of TVA and CLA. Feeding ruminally protected oilseed in spring had no effect on milk fat, TVA or CLA concentrations but in autumn increased (P<0.001) milk fat concentration. Feeding crushed rapeseed depressed (P<0.001) TVA and CLA concentrations. Ratios of fatty acid pairs dependent on D9-desaturase (C10:1/C10:0, C16:1/C16:0 cis-9 C18:1/C18:0 and CLA/TVA) were lower in milk from cows with harder milk fat and the C12:1/C12:0, C14:1/C14:0 ratios were similar for soft and hard milk fat cows. Feeding ruminally protected oilseed decreased (P<0.001) all ratios except for C12:1/C12:0 in autumn 2000. Feeding rapeseed had no effect on the product/substraight ratios except the cis-9 C18:1/C18:0 ratio. None of these ratios were associated with milk fat CLA concentrations in spring however in autumn C14:1/C14:0 and C16:1/C16:0 were positively associated (P<0.05). Significant associations (P<0.001) between the milk fat cis-D9 C18:1/C18:0 ratio and CLA concentration and between TVA and CLA concentrations were also evident. This suggests that milk fat CLA concentrations may be influenced more by the availability of TVA than by the variation in the activity of D9-desaturase.

Presidential Address 2002 Where is science taking society and where is society taking science? - Fisher MW (Proceedings of the New Zealand Society of Animal Production, 2003)
Pharming Hildagaard, a fringe theatre production telling of human cloning (Figure 1), is one way our society deals with the contentious nature of modern scientific developments. The fringe theatre production set at a fictitious research organisation in Hamilton, may have been a fantasy, sensationalist, and perhaps contained dodgy science (M. Servian, personal communication), but it was a story that attempted to engage the issues that cloning raises. While this may have been fringe or experimental theatre, opposition to genetic modification is more mainstream and “coming to a field near you”. Questions have been asked over where science is taking agriculture (Anon, 1998) and we might also ask where science is taking society, or where society is taking science? I want to use a number of great thinkers to reflect on how we deal with these questions, and thus how we deal socially with science.

Protein concentration in the rat maternal diet programs appetite and glucose metabolism in the offspring - Barnett MPG; Harris PM; Cooper GJS (Proceedings of the New Zealand Society of Animal Production, 2003)
The effect of dietary protein concentration throughout gestation and lactation on maternal appetite, and appetite and glucose metabolism of the offspring, was investigated. Female Sprague-Dawley rats were fed diets containing either 20% whey protein (control; C, n=20) or 5% whey protein (low-protein; LP, n=30) through gestation and lactation. LP mothers gained less weight during gestation (88 vs. 136 g, SED=18, P<0.01), and consumed less food during lactation (451 vs. 902 g, SED=77, P<0.001). C offspring were heavier at birth (6.5 vs. 5.3 g, SED=0.5, P<0.05), consumed more food (273 vs. 178 g, SED=15, P<0.05), and gained weight more rapidly (5.9 vs. 3.7 g/day, SED=0.4, P<0.001) than LP offspring. LP offspring had lower fasted blood glucose at 40 (2.2 vs. 3.5 mmol/L, SED=0.4, P<0.01) and 50 (2.9 vs. 4.8 mmol/L, SED=0.2, P<0.001) days of age and were more sensitive (P<0.001) in response to a glucose challenge at 30 (498 vs. 615 mmol/L min, SED=24), 40 (557 vs. 700 mmol/L min, SED=24) and 50 (535 vs. 781 mmol/L min, SED=44) days of age. These results show that maternal dietary protein concentration during gestation and lactation programs appetite and glucose metabolism in the offspring.

Ram Focus - matching rams to buyer flocks - Jopson NB; Amer PR (Proceedings of the New Zealand Society of Animal Production, 2003)
A new software package has been developed to assist ram breeders to target rams to buyers` flocks. "Ram Focus" leads the potential buyer through a short series of questions relating to the buyer’s current levels of animal performance, aims and future expectations. The answers to these questions are used to calculate economic values for individual traits, which are subsequently combined into an index customised for the buyer. The end result is that Ram Focus reranks the suitability of rams for alternative commercial flocks. Examples are presented of how the suitability of rams changes between commercial flocks, first using examples of differing reproductive performance, and second, differences in expectations of a drench failure.

Ranking maize hybrids for silage quality and milk production in pasture-based dairying - Kolver ES; Densley R; Miller D; Williams I; Sapienza DA (Proceedings of the New Zealand Society of Animal Production, 2003)
A large database (n=1611) of maize hybrid nutritive characteristics was developed by sampling 42 maize hybrids from three replicate plots at 100 Pioneer Research sites during 2000, 2001, and 2002. Compared to changes from year to year, differences in nutritive quality across hybrids of different maturity were small. Differences in maize hybrid quality accounted for $34 extra milk income per tonne of maize silage DM, whereas the differences in hybrid yield had a much larger impact on milk income ($8672/ha maize grown). Maize hybrids were ranked similarly for milk production potential, although the rankings were much closer, and sometimes equal for hybrids when fed in a New Zealand pasture system compared to a US total-mixed-ration system. Being able to select maize silage hybrids in New Zealand based on the extra milk they are likely to produce will be of benefit to dairy farmers, especially as inclusion rates of maize silage increase.

Recognising the limits to live weight-reproduction relationships in ewes - Rutherford L; Nicol AM; Logan CM (Proceedings of the New Zealand Society of Animal Production, 2003)
The relationship between joining live weight and ovulation rate and number of lambs born was examined in a composite flock of small- and large-framed ewes. Approximately equal numbers of small- (n = 315) and large (n = 305) framed, mixed-age ewes of equal average condition score, selected in the same proportion from 9 commercial flocks (mainly Coopworth), were managed together from early March to pre-lambing. The average pre-joining live weight (±SD) of small-framed ewes (61.3 ±6.35 kg). was significantly (P<0.001) lower than that of large-framed ewes (71.1±6.58 kg). Ewes were joined with 14 Coopworth ram hoggets fitted with ram harnesses on 8 April. Ewes marked by rams were temporarily removed from the flock every 7 days for 21 days and ovulation rate (0, 1, 3, 4) recorded by laparoscopy the following day after fasting. Pregnancy status (0, 1, 2 or more) was recorded by ultrasonography on 4 July. Ewes were fully recorded at lambing. The mean ovulation rate (OR) of small-framed ewes was significantly lower (1.76, P<0.05) than that of large-framed ewes (1.92). The regression of OR on joining live weight (jLW) was significant (P<0.001) for small-ewes (OR = 0.0216 x jLW + 0.463) but there was no relationship between OR and jLW in large-framed ewes. Maximum OR (1.92) was predicted to occur at 67.5 kg jLW. The results of this study indicate an upper limit to the live weight ovulation rate relationship. Compared on the basis of equal ewe live weight per ha, OR per ha was 12% higher for small- than large-framed ewes.

Reflections and visions in the deer industry - Loza MJ (Proceedings of the New Zealand Society of Animal Production, 2003)
The deer industry has changed markedly in the last 10 years in terms of productive capacity, market size, the nature of industry participants and their representative structures. It has survived and generally thrived despite significant business and global upheavals over this period. However, a number of fundamental issues remain unresolved and represent the industry`s greatest challenges. As the pace of change in technology, consumer needs and global markets picks up, the ability of the deer industry to continue to adapt to change and to respond decisively to local and global issues that arise will be increasingly important for its continued growth and success. Even within a two year horizon there are a number of critical decisions that will need to be taken that will determine the industry’s performance longer term.

Relationships between milk protein percentage and reproductive performance in Australian dairy cows - Fahey J; Morton J; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 2003)
The InCalf Project included a large, prospective, observational field study that described the reproductive performance of 29,462 dairy cows in 168 herds throughout Australia. Milk protein percentage was identified as one of six factors associated with herd reproductive performance. In this further study, a subset of the original database was used and then refined to only include Holstein cows with between one and five milk production records during the first 120 days of lactation in seasonal-calving herds which carried out artificial insemination (AI) for at least the first six weeks of the mating period. This subset then comprised 8,795 cows in 66 herds. Cows in the subset were divided into four quartiles based on early lactation milk protein percentage and five intervals from calving to mating start date (MSD). Three week submission rate and six-week in-calf rate were lower (P<0.001) and the 21-week not-in-calf rate was higher (P<0.001) for cows in the lowest compared to the highest quartiles for milk protein percent. The association between milk protein percentage and reproductive performance was driven mainly by the incidence of non-cycling cows with consequent effects on submission rate in the first three weeks of AI as well as in the second three weeks. In conclusion, late calving cows with low milk protein percentage were at the greatest risk of not being submitted for AI and remaining not in-calf at the end of a relatively long mating period of 21 weeks.

Reproductive productivity of young red deer hinds - Asher GW (Proceedings of the New Zealand Society of Animal Production, 2003)
Reproductive productivity of rising-two-year old red deer hinds on New Zealand deer farms has been a prominent issue over the last 10 years. On average, 16% of young hinds fail to establish pregnancy in their second year, although this figure masks wide between-farm variation. A growing body of ultrasound scanning data implicates failure of ovulation and/or conception at 16 months of age as the main influence on pregnancy rate. While such puberty failure in red deer has often been attributed to poor nutrition and failure of hinds to attain a critical threshold live weight of 65 -70 kg at 16 months, data on growth rates of young hinds from numerous farm monitoring programmes around the country largely debunk this concept. This paper reviews the potential causes of reproductive failure in young red deer, including the putative and actual influences of seasonal, social, stress and genetic factors on puberty failure. An emerging theme is the strong interplay of various environmental and genetic factors in determining the incidence of puberty.

Research on calving environments for farmed red deer: a review - Pollard JC (Proceedings of the New Zealand Society of Animal Production, 2003)
This review describes past research on suitable calving environments for farmed red deer and presents ideas on future topics for research. Neonatal mortality on deer farms is common, claiming 10-12% of calves born on average. Research carried out in the 1970s and observations of wild red deer identified three factors that were required to minimise behavioural problems and subsequent mortality of young calves: isolation of the hind from other deer, vegetative cover for the calves to hide in, and lack of disturbance by people. Subsequent studies have substantiated these observations but the needs for isolation and lack of disturbance cannot be readily fulfilled on intensive deer farms. Selection for deer that are tolerant of other deer and humans at calving time, and taming deer so that disturbance by humans is lessened, are areas in which future research may prove worthwhile.

A single-nucleotide polymorphism on Calpain-1 is associated with meat tenderness in cattle - Cullen NG; Page BT; Morris CA; Hickey SM; Dobbie PM (Proceedings of the New Zealand Society of Animal Production, 2003)
Variability in tenderness remains a major concern to the meat industry, and our objective was to identify genetic effects on beef meat tenderness, in animals treated alike, and under similar post-mortem processing conditions. A quantitative trait locus (QTL) for beef tenderness has been located on the same region of chromosome 29 in a United States Department of Agriculture (USDA) study and in our research. Micro-calpain, or calcium-activated neutral protease (CAPN1), has been identified as a candidate gene. The calpain/calpastatin system is involved in the change of tenderness with time, by regulating post-mortem proteolysis. The CAPN1 gene was sequenced by USDA workers who identified single-nucleotide polymorphisms (SNPs) in two exons. These results were followed up as part of the AgResearch Jersey-Limousin Beef QTL trial, where steak samples were obtained from the longissimus dorsi of 416 animals slaughtered at about two years of age. The segregating USDA and NZ families were both heterozygous for one of these SNPs, on exon 9, and this region was predicted to alter the protein sequence by the substitution of alanine for glycine in Domain II. Both families were genotyped for these two SNPs, as well as for six intronic polymorphisms, to define haplotypes. Analysis of tenderness measurements in the NZ data (n=81 animals) showed a difference between paternal CAPN1 haplotypes, with the SNP encoding alanine at amino acid number 316 being associated with more tender meat (decreased shear force) relative to the SNP encoding glycine (P<0.00001). The association of the maternal haplotypes with meat tenderness phenotypes (P<0.01) was also consistent with the hypothesis of CAPN1 as the gene underlying the QTL effect. The sire and dam effects together accounted for over 30% of the residual variance in tenderness. Our results show that a single SNP test in the laboratory can distinguish genetically tender and genetically tough animals at any age.

Strategies to encourage adoption: a case study of New Zealand farmers and their possum control practices - Parminter TG; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 2003)
Ecological scientists and policy agencies have identified possums (Trichosurus vulpecula) as a pest of both biodiversity and agricultural production. However it has been unclear whether farmers would take action to control possums for biodiversity reasons if their potential threat to agriculture was reduced. In 2002 a survey was made of New Zealand livestock farmers, of whom 85% had control measures in place. From the data, a regression model was developed for predicting farmers’ intentions to control possum numbers. The model had a squared multiple regression co-efficient of 62%. The individual regression coefficients all had F probabilities <0.001. It is apparent that possum control on farms is mainly undertaken to reduce the threat of bovine tuberculosis (Tb) in cattle. Farmers are also more likely to take steps to control possum numbers when they consider it will reduce pasture damage, contribute to an overall reduction in farm pests, and reduce damage to their fruit trees and gardens. Control is discouraged by risks of poisoning farm dogs and high costs. Policy agencies will need to work with scientists to provide the information landowners need to encourage their greater commitment to possum control even when the Tb threat has been reduced.

Structure and role of SIL in sheep genetic improvement in New Zealand - Cruickshank GJ (Proceedings of the New Zealand Society of Animal Production, 2003)
Sheep Improvement Ltd (SIL) has been developed to manage the national genetic database for the New Zealand sheep industry. Since its launch in 1999, SIL has gained acceptance as the provider of the industry standard sheep genetic analysis. As part of the greater industry, SIL has a key role to play in fostering the uptake of performance recording to maximise the rate of genetic improvement in the commercial flock, through improved ram breeding and selection decisions. Long-term benefits of genetic improvement are dependent on delivering scientifically advanced analysis to all members of an informed industry. This requires consistency of information, supplied at varying levels of complexity, but always in a simple, accurate and relevant form. SIL provides information in a flexible and easy to understand format, backed up by a strong focus on industry education. Continuous development focuses on delivering new outputs related to improved profitability, more accurate analysis, including major-gene effects as they become available, and greater flexibility at a computational level. Equally importantly, SIL will develop outputs to provide greater flexibility, relevance, ease of use and understanding by all users of genetic information.

Survival of in vitro-produced cattle embryos from embryo transfer to weaning - Smeaton DC; McGowan LT; Scott ML; Tervit HR; Cameron CA (Proceedings of the New Zealand Society of Animal Production, 2003)
New reproductive technologies present both the beef and dairy industries of New Zealand with numerous opportunities. A key factor in the successful use of these technologies is the reproductive rate obtained from their use. MOET (multiple ovulation and embryo transfer) is a fairly well established procedure to achieve pregnancy by embryo transfer. As an alternative, harvesting of oocytes, in vitro fertilization, culture, and subsequent embryo transfer (IVP-ET), also has potential. The technology is still relatively new and pregnancy rates of 30% have been reported. This is at least 10% lower than that achieved with MOET. As part of another project, approximately 400 recipient cows, in each of three years, were subject to ET using fresh IVP embryos. Pregnancy rates to calving, per embryo transferred, averaged 40, 44 and 33% in 1999, 2000 and 2001 respectively. Within years, average pregnancy rate varied from less than 20% to over 50% depending on recipient source (P<0.05), breed (P<0.01) and condition score (P<0.05). Once cows could be detected pregnant, at about 50 days after embryo transfer, they tended to stay pregnant through to calving. Neither embryo breed nor the type of oestrus-synchronizing device had a significant effect on pregnancy rate.

Valuing our farm environment - McCallum L; McCallum K (Proceedings of the New Zealand Society of Animal Production, 2003)
Lloyd and Kathy McCallum farm 447 ha at Lochiel on the Central Southland Plains. The milking platforms consist of two units each of 147 ha and 152 ha, the remaining being run-offs. We milk 850 Freisan/ Jersey X cows through two herring bone sheds on adjoining farms. The milking platform has two supporting run-offs one leased and the other owned. We have always been in the top 5% for production in the Southland area.

What is a better ram worth? - Meikle A; Amer PR (Proceedings of the New Zealand Society of Animal Production, 2003)
This paper presents equations that can be used to quantify the differences in value to a commercial farmer among rams available for purchase from a single ram breeder. The same approach can be taken for a group of breeders for which across-flock genetic evaluation results are available. Separate equations are presented in detail for buyers of both dual-purpose and terminal sire rams. A working version of the terminal sire equation incorporates the difference in the terminal sire index value between two rams, the number of years, and the number of ewes per year, to which the ram is to be mated and the tailing percentage in the commercial flock as variables. A working version of the dual-purpose sire equation incorporates the same variables as the terminal sire equation, but with the percentage of the ram`s daughters to be kept as replacement ewes also added.

Wintering systems for weaners in Otago and Southland - Lawrence D (Proceedings of the New Zealand Society of Animal Production, 2003)
Low winter temperatures, high rainfall and high incidences of poor draining soils in Southland combine to created potential problems with winter "pugging" and soiled pastures by red deer weaners. Four wintering options presently exist for weaners in this region; pasture grazing, winter brassica grazing, outdoor enclosures and indoor enclosures. While pasture wintering is still the most common system used, the other options are becoming increasingly popular to mitigate against pasture/soil damage. This review contrasts these various options, particularly with respect to outdoor and indoor enclosures, and highlights recommendations for successful adoption of these systems.

Wool yellowing and pH within Merino and Romney fleeces - Sumner RMW; Young SR; Upsdell MP (Proceedings of the New Zealand Society of Animal Production, 2003)
Fleece samples were taken from the back, side and belly of three adult ewes in one Merino flock and three adult ewes in one Romney flock in each of six regions of New Zealand (Waikato, Manawatu, Wairarapa, Marlborough, Canterbury, Otago). Each fleece was 12 months growth. These samples were used to compare factors associated with wool yellowing as measured by tristimulus (Y-Z) values. Neither the region of New Zealand where the sheep grazed nor the measured dimensional fleece characteristics, were related to fleece yellowing. The pH of an aqueous extract of greasy wool was strongly related (R2 = 0.93) to tristimulus (Y-Z) (base yellow) at shearing but less strongly related (R2 = 0.70) to tristimulus (Y-Z) after the sample had been incubated at 40°C and 100% RH for 6 d. Merino samples had a lower tristimulus (Y-Z), both before and after incubation, at a particular pH than Romney samples. Back wool did not increase in yellowness as much during incubation as side or belly wool possibly on account of photo-oxidation following prolonged exposure to sunlight. These data indicate a close relationship between pH of a water soluble component of greasy wool and the extent of wool yellowing that was influenced by sheep breed and body site.

Ammonia and urea utilisation in lambs infected with Trichostrongylus colubriformis and fed fresh lucerne (Medicago sativa) - Bermingham EN; Roy NC; Reynolds GW; Sinclair BR; Peters JS; Sutherland IA; Waghorn GC; Revell DK; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2002)
The effect of a Trichostrongylus colubriformis infections on ammonia and urea fluxes across the mesenteric-drained viscera (MDV), portal-drained viscera (PDV), and liver was investigated using an arterio-venous preparation in lambs fed fresh lucerne (Medicago sativa). The lambs were infected with 6000 T. colubriformis L3 larvae per day for 6 days (n=5) or kept as parasite free controls (n=5). On day 48 of the experiment, the lambs were infused continuously for 8 hours with r-aminohippuric acid (688 mg/h) into the mesenteric vein in order to measure plasma flow across the MDV, PDV and liver. Blood was continuously collected from the mesenteric artery and vena cava for consecutive two hour periods throughout the infusion period and plasma was harvested. Plasma concentrations of ammonia and urea were unaffected by the presence of intestinal parasites. Ammonia fluxes across the MDV, PDV, and liver were similar between treatment groups. Urea fluxes were also similar between treatment groups with the exception of the PDV, which showed a net release of urea in the parasite group and a net uptake by the control group (P=0.03). This suggests that the presence of a sub-clinical T. colubriformis infection does not increase the demand on the lamb for amino acids for ureagenesis.

Analgesia for velvet antler removal - Wilson PR; Bartels MM; Stafford KJ; Mellor DJ (Proceedings of the New Zealand Society of Animal Production, 2002)
This paper briefly reviews methods for analgesia of the velvet antler. Injection of 2% lignocaine hydrochloride (L) provides the most rapid and repeatable analgesia when given as a "high" dose ring block (1 ml/cm pedicle circumference). A "low site" regional nerve block has a long latency and low repeatability while a "high site" regional block also has a long latency but gives more repeatable analgesia after 4 minutes. Comparison of the dynamics of the alternative local anaesthetics showed L to have a mean analgesia onset time of 31 seconds and duration of 88 minutes. Mepivacaine (M) had a similar onset time, but a duration of 270 minutes, while two formulations of bupivacaine (B) had onset times averaging 48 and 87 seconds, and duration 270 and 460 minutes, respectively. Combinations of L+M, L+B and M+B had onset times equivalent to the most rapidly-acting component and duration equivalent to the longest-acting component. Electronic analgesia provides insufficient and non-repeatable analgesia and its application is a noxious stimulus in itself. Compression bands are approved in yearling stags in New Zealand. The effectiveness and possible aversiveness of high pressure compression bands on adult stags is under investigation. Pain and its control after antler removal, are yet to be studied comprehensively.

Analgesics: what use are they in farm animals? - Chambers JP; Stafford KJ; Mellor DJ (Proceedings of the New Zealand Society of Animal Production, 2002)
The use of analgesic drugs in veterinary practice is increasing, particularly in companion animals. However, farm animals often suffer from conditions (such as foot rot), or are subjected to operations (such as dehorning), which are likely to be painful. Assessment of pain in farm animals can present difficulties and analgesic drugs have not been investigated in any systematic way. Most assessment of analgesic drugs in ruminants has been carried out using experimental models of pain rather than clinical cases. Some indications for analgesics are obvious, such as castration and dehorning. Others are not so obvious, such as mastitis, which is very painful in women, and presumably in cows. Animals in pain are likely to be less productive and there is good evidence that chronic pain will change an animal`s metabolism adversely. Valid reasons for not using analgesics include cost and concerns about residues, which ultimately also means cost. There are several different classes of analgesics, with different attributes. Local anaesthetics are cheap, but short acting. Residues in food have not been an issue in the past, but concerns have been raised in Europe about some metabolites being carcinogenic. Morphine-type drugs are cheap, but less effective in ruminants than other species, are likely to cause residues in food and are strictly controlled by law. Adrenergic alpha-2 agonists are effective, but also cause sedation. Residues can be managed by relatively short withholding times. Probably the most effective analgesics for ruminants are the non-steroidal anti-inflammatory drugs, such as ketoprofen. These have long withholding times for meat, but zero for milk.

An attempt to suppress the rut- associated loss of live weight in stags by immunocastration - Barrell GK; Nicol AM; Keeley MJ (Proceedings of the New Zealand Society of Animal Production, 2002)
Two trials were conducted to study the effectiveness of vaccination of stags against gonadotrophin-releasing hormone (GnRH) for minimising the deleterious effects of the rut on their live weight and body condition. In March 2000, mature red deer stags (n = 10) received a s.c. injection of 1.0 ml of vaccine (Improvac®) or saline solution (controls) and a second injection three weeks later. Liveweight loss in the 10 weeks following the initial injection was not affected by the treatment (mean loss 28.6 ± 4.0 kg and 28.1 ± 4.2 kg for vaccinated and control groups, respectively). Plasma testosterone concentration was lower (P<0.05) in the vaccinated stags but there was no effect on scrotal diameter. In the following year, stags (n = 10) were injected with 2.0 ml of the vaccine or saline on 18 January and 8 February. Mean liveweight loss in 21 weeks was similar for vaccinated and control groups (41.2 ± 8.2 kg and 38.8 ± 7.2 kg, respectively) and there was no treatment effect on the reduction in body condition score. Although vaccinated stags had a lower (P<0.05) mean plasma testosterone concentration than control stags, this effect can be entirely attributed to stags (3 out of 4) that had been vaccinated in the previous year’s trial. It is concluded that vaccination of stags against GnRH does not overcome the loss in live weight which is associated with the rut in these animals.

Can forages match concentrate diets for dairy production? - Waghorn GC (Proceedings of the New Zealand Society of Animal Production, 2002)
Comparisons have been made between concentrate based total mixed rations (TMR) and grass dominant pasture for dairy production. Limitations to further improvement in cow performance have been indicated by the very high reticulo-rumen fill in New Zealand cows fed pasture, exceeding 22% of live weight, relative to United States cows fed either TMR or forage diets. The importance of high concentrations of structural fibre in ryegrass dry matter, moisture content of fresh forages and the very rapid eating associated with high utilization of pasture on New Zealand dairy farms will limit increases in feed intake and cow performance. Responses to ryegrass supplementation with high quality forages have been summarised together with suggestions for future research and farming systems to improve performance and profitability of cows fed forage diets.

Climate Change: The global problem requiring a global response - Rys GJ (Proceedings of the New Zealand Society of Animal Production, 2002)
The New Zealand Government has stated its intention to ratify the Kyoto Protocol to address climate change. This has set in train a period of intensive policy development to assess the implications, derive policy measures and establish the appropriate legislative framework to carry out these intentions. Agricultural emissions in New Zealand, and particularly ruminant emissions, place New Zealand in a unique position compared to other developed countries. Ruminant agriculture provides both a potential solution and a threat to New Zealand meeting its targets under the Kyoto Protocol. The Convenor of the Ministerial Group on Climate Change has indicated that research is an important element in seeking to reduce New Zealand’s greenhouse gas (GHG) emissions from agriculture. Animal science has an important role to play. Animal science in New Zealand is at the cusp of a new and exciting era. Any advances that scientists can make in unravelling, and finding practical solutions to reducing nitrogen throughput and methane emissions, whilst maintaining or increasing animal productivity, will have significant economic value to New Zealand. The background to the Kyoto Protocol, the Government’s response, and the opportunities provided to animal scientists, are discussed.

Computer simulation of Johne's disease in New Zealand cattle - Soons R; Heuer C; Jackson R; Groenedaal H (Proceedings of the New Zealand Society of Animal Production, 2002)
Control options for Johne’s disease (JD) are explored by computer simulation because intervention trials under field conditions would be too costly. The purpose of this review is to describe a simulation model developed in The Netherlands and adapted to dairy herds in Pennsylvania (USA). The paper consequently derives what information is required for the adaptation to New Zealand dairy herds and explains the methods by which that information is currently collected. The model ‘JohneSSim’ simulates the within herd development of JD based on time related changes. Time intervals are six months. JD is transmitted vertically through the placenta or from dam to calf around calving through direct contact, colostrum, rest milk or bulk milk, infected pasture, or through contact with adult replacement stock from other herds. Control options include test-and-cull, measures to prevent the infection of calves, vaccination, and grouping of animals by age. The simulation suggested that, in The Netherlands as well as in Pennsylvania, progressively improving calf-hygiene with little reliance on test-and-culling would decrease the prevalence considerably and was economically feasible (average benefit-costs-ratio excluding extra labor = 1.58). Test-and-cull was not economical even if a test with 80% sensitivity was available. Contract heifer rearing, colostrum management, and seasonal calving appear to be risk factors for transmission that have specific relevance for New Zealand dairy herds.

Concentrations of conjugated linoleic acid in milk from cows grazing pasture of fed a total mixed ration for an entire lactation - Audlist MJ; Kay JK; Thomson NA; Napper AR; Kolver ES (Proceedings of the New Zealand Society of Animal Production, 2002)
Conjugated linoleic acid (CLA) is a collective term for the range of conjugated isomers of linoleic acid (C182). These fatty acids occur naturally in milkfat and have proven anticarcinogenic properties in laboratory rodents (Ip et al., 1999). Additionally, the various isomers have other reputed benefits for human health such as enhanced bone mineralisation, antidiabetic effects, reduced atherosclerosis and immune system modulation (Whigham et al., 2000). Such potential benefits for human health have focussed international research on enhancing concentrations of CLA in milk and dairy products. Overseas data show that one way to increase the concentrations of CLA in milk is to change the diet of cows from a typical total mixed ration (TMR) to pasture (Kelly et al., 1998; White et al., 2001). This points to a potential competitive advantage for the New Zealand dairy industry, in which pasture is already almost the sole source of feed. Despite this there are no data confirming the beneficial effects of pasture for enhancing CLA under New Zealand grazing conditions. The experiment described here used an existing experiment to compare the concentrations of CLA in milk from cows fed TMR or grazing pasture for an entire lactation under New Zealand conditions.

Control of Johne's disease in dairy cattle - Burton L; Voges H (Proceedings of the New Zealand Society of Animal Production, 2002)
Control of Johne`s disease caused by Mycobacterium avium subspecies paratuberculosis (MAP) in dairy cattle has assumed significantly greater attention over recent years. The primary reasons are; possible increasing prevalence, an increase in the number of overseas control programmes, the continued scientific debate about the link with Crohn`s disease in humans, and the reported presence of MAP in commercial pasteurized milk sold in retail markets. Johne`s disease is a chronic wasting disease of ruminants worldwide. Accurate prevalence data does not exist for New Zealand. The best estimates available currently estimate the annual cost in New Zealand for dairy farmers to be between $3.8 million (based on 12% herd infection) and $31.7 million annually. It is likely that with the current control technology available the cost of control would exceed the on farm benefits, and therefore significant market access issues will have to be the basis for implementing a national control programme. For New Zealand to achieve control it is essential that the current prevalence be established and an understanding of the epidemiology within the New Zealand farming system be developed. Unlike many other diseases current tests available for Johne`s disease have low sensitivity which results in any testing programme failing to detect significant numbers of infected animals. Current areas being examined include test methods, vaccine and management practice modification. Additionally the possibility of genetic selection for resistant animals may be possible with the molecular genetic capabilities that are currently being developed in the bovine.

Is Crohn's Disease caused by M. avium subsp. Paratuberculosis? - Davies PR (Proceedings of the New Zealand Society of Animal Production, 2002)
Speculation that M. avium subsp. paratuberculosis (MAP), the infectious agent of Johne`s disease, might be involved in the aetiology of Crohn’s Disease (CD) in humans was first voiced in 1913. No supportive evidence was obtained until the organism was identified in cultures from a small number of CD cases in the 1980`s. Evidence accumulated over the last 15 to 20 years has left the medical community somewhat polarised about the possible role of MAP in Crohn`s disease. Technological advances enabling more sensitive detection of bacteria or their components (e.g. PCR, immunohistochemistry), or immunological responses to them, have not clarified the fundamental question of whether an apparent association between the presence of MAP and CD lesions may have any causal significance. The basis for concluding that MAP has a causal role in the aetiology of CD is unconvincing.

Dairy industry perspectives of methane emissions and production from cattle fed pasture or total mixed rations in New Zealand - Robertson LJ; Waghorn GC (Proceedings of the New Zealand Society of Animal Production, 2002)
This paper examines the significance of ruminant methane emissions for the NZ dairy industry at a time when NZ is about to ratify the Kyoto Protocol. We consider factors for practical methane mitigation, and a broad based research strategy for the development of measures to reduce methane emissions. A key factor in the process is the integration of methane mitigation research into existing research programs. We were able to incorporate methane measurements into a trial evaluating the performance of two dairy cow genotypes fed contrasting diets. Overseas genotypes produced 8-11% less methane, as a percentage of gross energy (GE) intake, compared to New Zealand genotypes and total mixed rations (TMR) resulted in similar energy losses to methane (% of GE) as pasture.

The dairy product value chain: new opportunities from a holistic approach? - Boland MJ (Proceedings of the New Zealand Society of Animal Production, 2002)
The value chain for dairy products extends from on-farm production, through manufacturing and distribution, to the final consumer. Using an integrated approach across the value chain, it is possible to produce products that better suit consumers’ needs or preferences and that return more value to the farmer using on-farm methods. This approach requires a change in mindset for the manufacturing industry, and can be successful only in an industry that is fully integrated from cowshed to consumer. Some examples are described in the context of the value chain, and set the framework for the following papers.

Digestion kinetics of ryegrass - Chaves AV; Waghorn GC; Brookes IM; Hedderley D (Proceedings of the New Zealand Society of Animal Production, 2002)
Changes in ryegrass maturation, with accompanying decreases in nutritive value and feed intake, have significant consequences for the dairy industry. Thus digestion kinetics of ryegrass were measured in samples differing in both physiological age (days after cutting) and calendar date to form a database that can be used as a guide to calculate the extent and type of supplement needed to match nutrient supply with requirements of grazing dairy cattle. Ryegrass pasture was mown on 21 August, 11 September, and 21 September and samples of approximately 2 kg were harvested from those dates at 7-14 day intervals for chemical analyses by cutting to 5 cm above soil level. These samples were used for in sacco and in vitro incubations to determine rate of digestion and proteolysis. The principal finding was a rapid decline in crude protein content from about 22.5% of DM harvested at 21 days to 7.2% for that harvested after 67 days. These changes were associated with increases in the neutral detergent fibre (NDF) fraction of the DM (42.1% to 56.3%) and in lignin concentration (2.49% to 3.07%). Changes were more rapid in late-cut than early cut forages. The principal consequences of increased maturity were slower degradation rates of DM (k= 0.067 to 0.038/hour) and CP (k= 0.122 to 0.052/hour) and less degradation of crude protein to ammonia. This data can be used in conjunction with dairy cow models (e.g., CNCPS) to predict animal performance.

Does an increase in lamb birth weight through mid-pregnancy shearing necessarily mean an increase in lamb survival rates to weaning? - Kenyon PR; Morris ST; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 2002)
Lambing percentages in New Zealand have risen over the past decade and will most likely continue to rise, while the price for lamb remains high in relation to wool. Any technique that can increase the birth weights of lightweight multiple-born lambs may increase survival rates to weaning. Mid-pregnancy shearing as a possible technique to increase lamb survival under commercial conditions was examined in the present study. Mid-pregnancy shearing was found to significantly (4.7 vs 5.1kg, P<0.05) increase the birth weights of twin-born lambs but had no effect on birth weight of singletons or triplet-born lambs. Both the magnitude of the response, and the fact that it did not occur in all birth ranks, are consistent with previous mid-pregnancy shearing studies. Mid-pregnancy shearing had no significant effect on lamb survival rates to weaning. To achieve an increase in survival rate to weaning through an increase in lamb birth weight alone, the lamb must be born within a birth weight survival range below optimum, and the increase in birth weight must be large enough to move a significant proportion of these lightweight lambs into a higher survival rate range.

Does feeding sulla (Hedysarum coronarium) reduce methane emissions from dairy cows? - Woodward SL; Waghorn GC; Lassey KR; Laboyrie PG (Proceedings of the New Zealand Society of Animal Production, 2002)
Most of New Zealand’s methane is generated as a by-product of feed fermentation in the rumen of livestock and is released through the mouth and nose. An experiment conducted in late summer using Friesian and Jersey dairy cows investigated whether feeding sulla (Hedysarum coronarium), a condensed tannin (CT)-containing legume, reduced methane emissions without compromising milksolids production. Cows grazing sulla had higher intake (DMI; 13.1 vs. 10.7 kg DM/cow/d, P<0.001) and milksolids production (1.07 vs. 0.81 kg MS/cow/d, P<0.001) than cows grazing perennial ryegrass pasture. Total daily methane emissions were similar (253.9 vs. 260.0 g CH4 /cow/d, ns). However, cows fed sulla produced less methane production per unit DMI (19.5 vs. 24.6 g CH4 /kg DM, P<0.05) and per unit milksolids yield (243.3 vs. 327.8 g CH4 /kg MS, P<0.01) than those fed ryegrass due to the higher nutritive value of sulla compared with the ryegrass, and possibly the presence of CT. Further research will determine whether feeding alternative, high quality forages is a viable methane mitigation option for New Zealand dairy farm systems, but results of this study clearly indicate that CT-containing legumes, such as sulla, do effectively reduce methane emissions from dairy cows without compromising milksolids production.

Does mid-pregnancy shearing affect lamb fleece characteristics - Sherlock RG; Kenyon PR; Morris ST (Proceedings of the New Zealand Society of Animal Production, 2002)
Mid-pregnancy shearing has been promoted as a technique to increase both lamb birth weight and survival in multiple-born lambs. Mid-pregnancy shearing has also been shown to increase dam wool quantity and quality and, in some instances, increase lamb growth rates until weaning. It has also been suggested that shearing of the dam during pregnancy results in a change in the lamb’s fleece characteristics. The aim of this study was to further investigate the effect of dam shearing treatment on lamb fleece characteristics. Thirty-one singleton and 29 twin-born lambs were born to either mid-pregnancy shorn or unshorn Romney ewes. At 6 months of age the lambs were midside sampled (to allow measurement of staple length (SL), washing yield, loose wool bulk, colour and mean fibre diameter (MFD)). A skin biopsy was taken from the midside to measure the ratio of secondary to primary follicles. The lambs were shorn three weeks later and a fleeceweight was obtained. Lambs born to shorn dams had a higher MFD (32.9 vs. 31.3mm, P<0.05) and had slightly whiter wool (0.1 vs. 0.3, P=0.07) than their counterparts born to unshorn ewes but did not differ for yield, SL or bulk. The higher MFD found in the lambs born to shorn ewes was associated with a decrease in the number of secondary follicles (P<0.05) without a significant decrease in the number of primary fibres. There was a significant interaction (P=0.05) between birth rank and shearing treatment on fleeceweight such that twin-born lambs born to shorn dams tended to have heavier fleeces (by 170g) than those born to unshorn dams, this relationship was not observed in singleton lambs. This study suggests that for singleton lambs, mid-pregnancy shearing of the dam will have no appreciable effect on wool value. However in twin-born lambs an increase in fleece weight may offset any decreased value due to higher MFD.

Dynamic selection for sheep genetic improvement - Amer PR; Jopson NB; McEwan JC (Proceedings of the New Zealand Society of Animal Production, 2002)
Dynamic selection is a process used in livestock improvement programmes to maximise genetic progress while constraining the long term rate of inbreeding. An optimisation algorithm identifies proportions of genes each selection candidate should contribute to the next generation. Application of dynamic selection procedures to select cull and replacement ewes, and then subsequently to select a ram team, was demonstrated using data from a Romney sheep breeder. When compared with selection based on an index of breeding values alone, dynamic selection of cull and replacement ewes reduced the accumulation of relatedness by approximately 85% of the average annual accumulation from 1994 to 2000. To achieve this, approximately 33% of the average annual genetic progress in average index value was sacrificed. Using dynamic selection to identify a ram team to be mated to selected ewes resulted in a saving in relatedness by an amount equal to the average annual accumulation from 1994 to 2000 with only a very modest drop in genetic progress of 9% of the average annual genetic progress in average index value. This study has demonstrated that dynamic selection tools could, when practically applied to sheep breeding populations, provide a transparent and efficient means of managing the tradeoff between rate of genetic progress and rate of accumulation of relatedness.

Effect of a Total Mixed Ration diet on the concentration of amino acid-derived volatiles in milk - Lane GA; Fraser K; Kolver ES; Rowan DD; Allen JM; Mills OE; Abraham AS; Olney SD (Proceedings of the New Zealand Society of Animal Production, 2002)
The flavour chemistry of milk from Holstein-Friesian cows of two genotypes fed total mixed rations (TMR) or pasture has been compared over three years. Mean concentrations of selected milk aroma compounds, namely skatole, indole, dimethylsulphide, toluene, and of total p-cresol (determined after hydrolysis of conjugates) were significantly lower (10% to 39% of pasture treatment, P < 0.01) in the milk from the TMR-fed cows. Mean milk non-protein nitrogen (NPN) and dietary crude protein content (CP) were lower (93% and 67% of pasture treatment respectively) for the TMR diet. These results are consistent with an origin for these aroma compounds in the degradation of dietary protein amino acids in the rumen. However, concentrations of total m-cresol, which is not thought to derive from dietary protein, were also lower in the milk from TMR-fed cows (19% of pasture treatment). In addition, for the pasture treatment, the patterns of variation of concentrations of skatole, indole and p-cresol and NPN in milk and of dietary CP differed considerably between different periods within a dairy season. These findings indicate that factors additional to CP supply are important in the metabolism of these flavour compounds.

Effect of body condition at calving of milkfat composition of Friesian heifers during the first ten weeks of lactation - Thomson NA; Bryant MO; Chand A; MacGibbon AKH; Chagas LM (Proceedings of the New Zealand Society of Animal Production, 2002)
The effects of live weight and body condition score (CS) at calving on milksolids production has been well documented. The effects of CS at calving on detailed composition of milk, the physical characteristics, or, product quality are largely unknown. Milkfat yield, fatty acid profile (FAP), solid fat content (SFC) of milkfat during the first 10 weeks of lactation were monitored for Friesian heifers with a pre-calving CS of 4.1 (LCS) or 5.2 (HCS). Once calved, all heifers were grazed as one herd and offered pasture ad libitum. Composition and characteristics of milkfat were determined at four, six, and 10 weeks postpartum. At four weeks postpartum the HCS heifers, produced 23% more (P<0.001) milkfat, lost 59% more (P<0.001) live weight and CS declined 30% more (P<0.05) than did LCS heifers. Associated with these changes were compositional changes in milkfat. CS at calving had no effect on milkfat concentration. HCS heifers produced milkfat with lower concentrations (P<0.01) of de novo synthesised fatty acids (C4:0-C15:1) and higher (P<0.01) concentrations of preformed fatty acids. Concentration (mg/100 mg milkfat) of oleic acid (C18:1) was higher: 27.4% c.f. 24.8%, s.e.d. 0.94 (P<0.001) for HCS compared with LCS heifers. Milkfat from HCS heifers was softer, SFC at 5°C (55% c.f. 59%, s.e.d. 1.2, P<0.01) than from LCS heifers. Six weeks postpartum, the differences in FAP persisted but changes in live weight and CS were small compared with the first four weeks of lactation. Ten weeks post calving both groups were gaining live weight, but although differences (P<0.01) in live weight, CS, and daily milkfat yield persisted, no differences in FAP or SFC were found. These results show that differences in pre-calving live weight and CS cause differences in the composition and characteristics of milkfat. Milkfat from HCS heifers was more desirable (softer and higher in unsaturated fatty acids) than from LCS heifers. These differences disappeared once the two heifer groups were in positive energy balance by 10 weeks postpartum.

The effect of condensed-tannins in fresh Sulla (Hedysarum coronarium) on the net flux of fatty acids across the mammary gland and their secretion in the milk of lactating ewes - Roy NC; Knight TW; Reynolds GW; Deighton MH; Death AF; Sinclair BR; Peters JS; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2002)
Twelve sheep were surgically prepared with catheters in the mesenteric artery and mammary vein and a transonic flow probe around the pudendal artery to quantify the effect of condensed-tannins (CTs) on net mammary flux of fatty acids (FAs) and their secretion in milk. Two weeks later (Day 0), sheep were fed fresh Sulla (1500 g DM/d), which contains medium to high concentration of CTs (43.7 g CTs/kg DM). Six ewes were orally drenched (four times/d) with polyethylene glycol (160 g/d in water) to remove the effects of CTs; the remaining ewes received water. On Day 28, the mammary plasma flow and net flux of most FAs were similar between treatments. Arterial supply of C23:0, C18:2, C18:3, C20:1 and C22:5 to the mammary gland was increased (P<0.10) with CTs. The increase for C18:2 and C18:3 was concomittant with increased (P<0.10) concentrations in milk. No effect of CTs on total fat concentration and yield in milk was observed. Conclusions from this study indicate that CTs in Sulla increased the milk concentration of C18:2 and C18:3 by increasing arterial supply of these FAs to the mammary gland.

The effect of cysteine and glutamine supplementation on sheep infected with Trichostrongylus colubriformis - Hoskin SO; Lobley GE; Coop RL; Jackson F (Proceedings of the New Zealand Society of Animal Production, 2002)
This indoor study investigated the effect of direct daily abomasal supplementation of both cysteine (cys; 1g) and glutamine (gln; 5g) on a 12-week subclinical Trichostronglylus colubriformis trickle infection in lambs. Parasite infection increased the total number of leucocytes and eosinophils in peripheral circulation, nitrogen excreted in faeces and urine (P≤0.01) and plasma total protein concentration (P<0.05). Infection also reduced liveweight gain and plasma albumin concentration (both P<0.001), but did not alter feed intake. Supplementation increased nitrogen retention (P<0.05), tended to increase phe (P=0.056) and cys (P=0.097) flux, reduced the number of circulating eosinophils (P<0.001) and changed the pattern of faecal egg counts (P≤0.05), with no effect on final nematode counts. This experiment showed supplementation with two non-essential amino acids alone can elicit changes in the response of sheep to internal parasite infection.

The effect of endophyte alkaloids on diet selection by sheep - Cosgrove GP; Anderson CB; Phillot M; Nyfeler D; Hume DE; Parsons AJ; Lane GA (Proceedings of the New Zealand Society of Animal Production, 2002)
Sheep have a strong preference for clover in summer. One explanation for this may be the avoidance of alkaloids such as lolitrem B, ergovaline and peramine that are produced at that time of the year by endophytic fungi in ryegrass. We tested this hypothesis by exposing groups of three sheep to three food items (ryegrass with wild-type endophyte (E+), ryegrass with no endophyte (E-), and white clover (CL)), in December and in February. Each food was offered singly and in pairs, and time spent grazing on each food, short-term dry matter (DM) intake rate, and preference was measured. In February, sheep given E+ or E- ryegrass alone, grazed for 400 mins/day, compared with 370 mins/day when given a choice between them (P=0.15, SEM=14). The time spent grazing on the E+/E- choice was comprised of 280 mins/day on E- and 90 mins/day on E+ indicating a strong preference for E-. When offered ryegrass and white clover, the total grazing time (335 mins/day), and the grazing time on clover (285 mins/day) and on ryegrass (50 mins/day), were similar for E+/CL and E-/CL. Short-term dry matter intake rate of grass (3.4 g DM/min), and the strong preference for clover in this study, were unaffected by the presence of endophyte. We conclude that while sheep detect endophyte alkaloids, they avoid eating them only when doing so does not reduce daily intake or change the proportion of grass and clover in their diet.

Effect of grazing undrenched weaner deer on chicory or perennial ryegrass/white clover pasture on gastrointestinal nemotode and lungworm viability - Schreurs NM; Molan AL; Lopez-Villalobos N; Barry TN; McNabb WC (Proceedings of the New Zealand Society of Animal Production, 2002)
Internal parasites can reduce animal performance (Moss & Vlassoff, 1993) and lungworm has been known to cause death in young deer (Mackintosh et al., 1984). Increasing numbers of drench resistant parasite populations being found on farms throughout New Zealand (Sangster, 1999) and pressure from consumers to reduce anthelmintic input for fear of residues in pastoral-based food products (Williams, 1997), signifies a need to find alternative methods of internal parasite control. Hoskin et al. (1999) found that undrenched weaner deer grazed on chicory did not have impaired growth rates and faecal egg counts were lower compared to similar animals grazed on perennial ryegrass/white clover pastures. This suggests that chicory has the potential to be used in farming systems to reduce the negative impact of internal parasites. This study looked at the viability of internal parasites that had travelled through the digestive tracts of deer grazing chicory (Cichorium intybus) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens)- dominant pasture. The hatching ability of gastrointestinal nematode eggs, the development of gastrointestinal nematode and lungworm larvae and the motility of L1 lungworm larvae were measured. The study also determined the effect of adding condensed tannins (CT), extracted from chicory, to rumen and abomasal fluid on L1 lungworm larval migration. CT are a group of phenolic secondary plant compounds found in chicory at concentrations of approximately, 4.2g/kgDM (Terrill et al., 1992).

Effect of transport stress on somatic cell counts in dairy goats - McDougall S; Anniss FM; Cullum AA (Proceedings of the New Zealand Society of Animal Production, 2002)
Somatic Cell Counts (SCC) are commonly used as an indirect measure of prevalence of bacterial infection and of milk quality in dairy cattle. However, interpretation of SCC in dairy goats is more complex due to a higher basal SCC and the fact that SCC appear to be influenced by a number of factors other than bacterial infection. Increased SCC is associated with bacterial infection of the udder in goats (Dulin et al., 1983; Ryan et al., 1993; Poutrel et al., 1997). However, SCC in goats also increases with age (Dulin et al., 1983), increases as lactation progresses (Dulin et al., 1983; Kalogridou-Vassiliadou et al., 1992; Wilson et al., 1995), varies among breeds (Sung et al., 1999) and increases as milk production declines (Zeng & Escobar, 1994; Pizzillo et al., 1994). Stressors such as change in nutrition, kidding, oestrus and vaccination have also been suggested as causes of increased SCC in goats (Lerondelle et al., 1992; Aleandri et al., 1994; Pizzillo et al., 1994; Zeng et al., 1997). The stress response includes both corticosteroid release from the adrenal cortex in response to adrenocorticotrophic hormone (ACTH) and adrenal medulla release of the catecholamines adrenaline and noradrenaline (Tyrrell et al., 1991). Injection of dairy cattle with exogenous ACTH results in an elevation in circulating leukocyte counts but no change in the SCC (Paape et al., 1973, 1975). However, transportation is likely to release both corticosteroids and catecholamines and has been used to examine various physiological responses in goats (Sanhouri et al., 1989; Greenwood & Shutt, 1992) …

Effect of udder health on milk - Lacy-Hulbert SJ; Auldist MJ (Proceedings of the New Zealand Society of Animal Production, 2002)
Mastitis is an inflammation of the udder tissue, normally arising from a bacterial infection. The effects of mastitis on the processing properties of milk have been widely researched over the past 40 years. This paper summarises the main effects of udder health on raw milk composition and its processing properties, reviews the progress made to date by the New Zealand dairy industry with regard to reducing the impact of mastitis on milk processing, and highlights continuing avenues of enquiry.

The effects of mid-pregnancy nutrition and shearing on ewe body reserves and foetal growth - Jopson NB; Davis GH; Farquhar PA; Bain WE (Proceedings of the New Zealand Society of Animal Production, 2002)
In an experiment replicated over three years, ewes were individually fed concentrate diets containing two levels of protein (12 and 18%) at either maintenance or 1.5 x maintenance from days 35 to 74 of pregnancy, and then at an allowance of approximately 2.0 kgDM/head/day on pasture until parturition. Half of the ewes within each treatment were shorn on day 74. Ewes were CT scanned to measure body composition at days 35, 74, 115 and 140 of pregnancy. Neither protein nor energy level fed during mid-pregnancy had any significant effects on conceptus growth, birth weight or lamb skeletal measurements. Shearing resulted in changes in ewe body composition as well as an increase of 0.36 kg (P<0.01) in lamb birth weights. Lambs from the shorn ewes were 14 mm longer in length (P<0.05) but 8 mm shorter in height (P<0.05) than those from unshorn ewes. Shorn ewes lost 1.3 kg more body fat (P<0.001) than their unshorn contemporaries over the second half of pregnancy. Unshorn ewes lost 0.74 kg of carcass lean over this period, while the shorn ewes gained 0.22 kg (P<0.001). The results show that ewes can be fed maintenance during mid-pregnancy if this allows good quality feed reserves to be built up in front of them for the third trimester. Mid-pregnancy shearing is likely to increase lamb survival in multiple born lambs through higher birth weights.

Effects of pregnancy on the fever response of sheep to a Gram-negative pyrogen - Breen GP; Barrell GK (Proceedings of the New Zealand Society of Animal Production, 2002)
Ewes commonly display a reduction of immunity to gastrointestinal parasites during the periparturient period, so it is possible that other components of immunity change at this time. To determine whether the reported absence of fever in full-term-pregnant ewes occurs in a breed farmed commercially in New Zealand, 12 pregnant and 9 non-pregnant Coopworth ewes were treated with injections of Escherichia coli lipopolysaccharide (LPS) at five-weekly intervals for 3.5 months. An initial dose-response study, conducted in a separate group of ewes, determined that a dose of 200 ng/kg LPS induced fever (≥ 0.7°C increase in rectal temperature) in our sheep. Rectal temperature and plasma glucose concentration were monitored at the time of LPS injection and 4 h later. The magnitudes of both the mean increase in rectal temperature (range 0.4 to 2.1°C) and the mean reduction of plasma glucose concentration (range 2.9 to 17.7 mg/dl) appeared to vary throughout the study but they were not affected by pregnancy, nor was there any difference in these parameters between the two groups of sheep at the periparturient period. However, there was a reduction in the incidence of fever generated by LPS in the post-lambing period, lactating ewes appearing to have smaller increases in rectal temperature (mean increase 0.4°C, n = 11) than their non-lactating counterparts (mean increase 0.8°C, n = 8). We conclude that at least part of the immune response to LPS, i.e., fever and the reduction of plasma glucose concentration, is maintained in our Coopworth ewes at full-term of pregnancy.

The effects of sheep breed on the defects pinhole and raised rib - Cooper SM (Proceedings of the New Zealand Society of Animal Production, 2002)
The effect of sheep breed and wool type on the incidence of the skin defects "pinhole" and "raised rib" was investigated. Six breeds/crosses were used - pure Romneys and Suffolk x Romney, Dorset x Romney, East Friesian x Romney, Texel x Romney and Merino x Romney crosses. Skins were recovered at slaughter and processed to dyed crust leather, then scored numerically for the severity and extent of pinhole and graded into the "Run" (best quality), "Pinhole", and "Thirds" grades. The presence or absence of raised rib on the skins was noted. Wool bulk and fibre diameter were measured. Skins from Romneys had the least pinhole and Merino crosses the most. Skins from Texel, Dorset and East Friesian crosses were also significantly more likely to be downgraded due to pinhole than those from Romneys. Within-breed differences in the level of pinhole were due to wool bulk differences, with a higher wool bulk correlated with more pinhole. Merino-cross skins were much more likely than the skins from pure-bred Romneys or the other crosses to have raised rib. Texel-Romney-cross skins were more likely than pure-bred Romney skins to have raised rib. There was no difference between the mean wool fibre diameter for ribby and non-ribby skins, but the ribby skins had a significantly higher wool bulk.

Effects of time-of-calving on dairy production: a farmlet study - Audlist MJ; MacDonald KA; Thomson NA; Coulter M; Lancaster JAS; Penno JW (Proceedings of the New Zealand Society of Animal Production, 2002)
Most dairy cows in New Zealand are calved just prior to spring in order to maximise pasture utilisation. This practice is associated with marked irregularities in the volume and composition of milk supplied to factories, which is a major limitation of seasonally-calving, pasture-based dairying systems. The need to accommodate peak milk flow means that manufacturing plants are underutilised for most of the season. Further, changes to milk composition can make it difficult to manufacture dairy products of high quality during some parts of the season, which necessitates the storage of product to meet out-of-season demand. Such irregularities are caused by a number of factors, including nutritional factors associated with the changing quality and availability of pasture, and physiological and hormonal factors associated with the stage of lactation of the cows (Auldist et al., 1997). One way of manipulating the lactation curve of the cows may, therefore, be to adjust the time of the year at which calving occurs. A previous study in New Zealand showed that autumn calving herds could be as profitable as spring calving herds (Garcia et al., 1998). In that study, nutritional demands were matched with pasture availability by adjusting stocking rate and feeding varying amounts of pasture and maize silage when required. A premium for winter milk was also applied. The current study was designed to investigate the effects of calving at four different times of the year on milk production in farmlet systems which were otherwise similar in stocking rate and other farm management variables.

Efficacy of antibiotic treatment at drying off in curing existing infections and preventing new infections in dairy goats - Anniss FM; McDougall S (Proceedings of the New Zealand Society of Animal Production, 2002)
Infusion of antibiotics into the udder at the end of the lactating period (“dry cow therapy”; DCT) is an essential control measure for bovine mastitis (Smith et al., 1967). Dry cow therapy eliminates existing intramammary infections (IMI) and reduces the incidence of new infections over the dry period with a resultant reduced prevalence of IMI at the commencement of the subsequent lactation (Smith et al., 1967; Harmon et al., 1986). The cure rate of existing infections after DCT has been reported as between 60-90% (Pankey et al., 1982; Sol et al., 1994; Browning et al., 1990; Williamson et al., 1995). Dry cow therapy reduces the new IMI rate by approximately 50% (Browning et al., 1994; Williamson et al., 1995). Infusion of antibiotics at the end of lactation in dairy goats (“dry-goat therapy”; DGT) has been reported to cure between 66% and 100% of existing IMI (Fox et al., 1992; Poutrel & de Cremoux, 1995; Poutrel et al., 1997). However, the efficacy of DGT in reducing the new infection rate over the dry period has not been examined. The aim of this trial was to assess the efficacy of intramammary antibiotic treatment of dairy goats at the end of lactation in curing existing mammary gland infections and reducing the incidence of new infections over the dry period and early in the subsequent lactation.

Endogenous synthesis and enhancement of conjugated linolieic acid in pasture-fed dairy cows - Kay JK; Mackle TR; Auldist MJ; Thomson NA; Bauman DE (Proceedings of the New Zealand Society of Animal Production, 2002)
The primary conjugated linoleic acid (CLA) isomer in milkfat, cis-9, trans-11 CLA, is a proven anticarcinogen in rodents and can be derived directly from ruminal biohydrogenation of linoleic acid. The major fatty acid in pasture, however, is alpha-linolenic acid; the biohydrogenation of which does not produce cis-9, trans-11 CLA as an intermediate. Therefore, in grazing cows, cis-9, trans-11 CLA must be produced by other sources, possibly via D9-desaturation of trans-11 vaccenic acid (TVA), a biohydrogenation product of both alpha-linolenic acid and linoleic acid. Studies were conducted to i) determine the importance of endogenous synthesis of cis-9, trans-11 CLA in pasture-fed cows and ii) increase the level of cis-9, trans-11 CLA. The first study involved abomasal infusion of sterculic oil (SO) to inhibit the activity of the D9-desaturase enzyme. Abomasal infusion of SO decreased the concentration of cis-9, trans-11 CLA in milk fat by 71% (P<0.01; 3.6 c.f. 12.1 ± 0.15 mg/g fatty acid). The presence of cis-9, C 1 0:1, cis-9, C12:1 and cis-9, C14:1 in the milk fat of cows following SO treatment indicated D 9-desaturase was not completely inhibited. Using the changes in these fatty acids to evaluate the extent of D9-desaturase inhibition with SO treatment, an estimated 87-100% of cis-9, trans-11 CLA in milk fat was of endogenous origin. In the second study, sunflower oil at 4% DMI/cow/day invoked a 38% increase (P<0.01) in milk fat TVA (61.3 c.f. 44.4 ± 0.51 mg/g fatty acid) and a subsequent 28% increase (P<0.01) in cis-9, trans-11 CLA concentrations compared to control (28.5 c.f. 22.3 ± 0.19 mg/g fatty acid). Results demonstrate that endogenous synthesis is the major source of cis-9, trans-11 CLA in pasture-fed dairy cows and levels can be enhanced by increasing the supply of the ruminally-derived precursor, TVA.

An evaluation of sulla (Hedysarum coronarium) with pasture, white clover and lucerne for lambs - Burke JL; Waghorn GC; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 2002)
Pasture-based diets restrict animal performance, due to limitations in voluntary feed intake and release of nutrients during digestion failing to meet nutrient requirements. Opportunities for improving the efficiency of pasture utilisation include the addition of a soluble carbohydrate source to enable an improved capture of ammonia by rumen bacteria, or the inclusion of condensed tannins (CT) to reduce protein degradation. A feed evaluation trial was conducted at AgResearch Grasslands to investigate the ability of sulla, a forage containing high concentrations of soluble carbohydrate and CT, to complement pasture and legume species. Fifty-six weaned ram lambs were allocated to seven diets: pasture (80% ryegrass and 20% white clover), white clover, lucerne, sulla, and 50:50 mixtures (DM basis) of pasture:sulla, white clover:sulla and lucerne:sulla. Lambs fed sulla, white clover, white clover:sulla and lucerne:sulla had the most rapid daily gains (256-263 g/day) while lambs fed pasture gained 105 g/day, respectively. Wool growth was influenced by diet. Sulla added to pasture, white clover and lucerne diets significantly reduced rumen ammonia concentrations and acetate:propionate ratios in lambs. Lamb performance can be improved by combining sulla with pasture and lucerne, and rumen parameters can be used to explain animal performance differences.

Factors associated with yellowing within Romney - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 2002)
Four two-year-old Romney ewes born in the Waikato and four two-year-old Romney ewes born in Canterbury that had been grazed together in the Waikato for 12 months, were used to investigate aspects of yellowing in wool samples grown on the mid-back, mid-side and mid-belly. Two sheep in each sub-group had a history of having a relatively high and two sheep a relatively low, propensity for their fleece to turn yellow during the previous year. Dimensional fibre characteristics, with the exception of staple length, were not significantly different between body sites, between the propensity groups or between birth farm groups. Wool was shorter on the belly than on the other two sites. Incubating greasy sub-samples of each fleece at 40°C and 100% relative humidity for 6 d induced a curvilinear increase in yellowness with the CIE Y - Z value approaching an asymptote. A significant amount of the variation in yellowing was explained by the concentration of K, Ca and possibly Na, elements secreted in the suint. These data suggest that the propensity of a fleece to turn yellow is not related to fleece architecture or the elemental composition of the fibres, but may have a physiological basis possibly related to sweating behaviour.

Factors influencing inducing decision-making in dairy cows: a case study of scientists' and producers' views - Botha CAJ; Verkerk GA (Proceedings of the New Zealand Society of Animal Production, 2002)
The purpose of this investigation was to identify and describe the on-farm decision-making context of dairy farmers when they decide to induce dairy cows. A social researcher facilitated the meetings between a Waikato dairy farmer and two collaborating groups, to gather and record data regarding on-farm induced parturition decision-making over a year. These sessions took place at times when decision-making would impact most on induction. Cognitive mapping was used to capture the context within which decision-making in connection with inducing dairy cows took place. The following main conclusions were made: a long term perspective of induction is required; the induction decision-maker does not have control over all the factors that influence induction but could foresee and manage several of them by appropriately using applicable records; cow condition plays a critical role; the focus farmer had a much more straightforward view than scientists of induction and viewed it on a time line; decision-making with regards to inducing cows is a continuous process and capturing it requires a systems perspective; the interactions between different factors that influence induction become more apparent and more obvious to participants when these factors were made visual through the cognitive mapping technique.

Genes with major effects on wool traits detected in Finn cross sheep - Bray AR; O'Connell D; Saville DJ (Proceedings of the New Zealand Society of Animal Production, 2002)
Two Finn sires with short wool staple lengths (Finn-S1 91 mm, Finn-S2 107 mm) and two with long staple lengths (Finn-L1 147 mm, Finn-L2 133 mm) were joined with Dorset Down (staple length 37-120 mm) and Romney (staple length 105-166 mm) ewes. Over two years, each ram sired between 83 and 210 progeny. Wool characteristics of progeny were measured at 6 months of age. For all sire groups, distributions of fibre diameter, fibre curvature, fibre medullation and clean fleece weight were not significantly different from single normal distributions. Similarly the distributions of fibre diameter coefficient of variation (FDCV), staple-crimp frequency and staple length for progeny of Finn-S1, Finn-S2 and Finn-L1 were close to unimodal. In contrast, the same three traits for progeny of Finn-L2 fitted two normal distributions. For all three traits, the mean value of one of the distributions of Finn-L2 progeny was similar to the means of the other three sire groups, while the mean of the second distribution was 41% greater (FDCV), 65% greater (staple length) or 67% less (crimp frequency) than that of the first. These results suggest the presence of a gene or genes with major effects on fibre traits.

Genetic engineering and the public: Attitudes, beliefs, ethics and cows - Small BH; Peddersen JA; Wilson JA; Parminter TG (Proceedings of the New Zealand Society of Animal Production, 2002)
A postal survey (n = 1682, margin of error 3%) used a hypothetical milk product with medical benefits produced by genetically engineered (GE) cows as a stimulus to examine New Zealanders` support and attitudes towards GE for food and medicine. Beliefs about proposed benefits of GE, ethical issues associated with GE, and ethical perceptions about the status and treatment of cows were canvassed. Ten times as many respondents totally opposed GE food as totally supported it. Medical applications (15.6%) received significantly more total support than GE food production (3.4%). A majority of respondents were prepared to support GE under some circumstances (medicine 61.8%, food 51.7%) - implying their need for case-by-case analysis. Respondents disagreed GE will: cure the world`s major diseases, solve the world`s food problems, improve the quality of animal lives, be environmentally benign, or that the spread of GE organisms can be controlled. GE did not fit with respondents’ cultural and spiritual beliefs or basic principles. Although agreeing the instrumental use of cows by humans was acceptable, respondents strongly disagreed genetic modification of cows for human benefit was acceptable. Consistent significant differences were found between males and females on all the above issues.

Genetic opportunities to improve milk value in New Zealand - Lopez-Villalobos N; Garrick DJ; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 2002)
The value of milk in New Zealand can be improved by altering its composition by genetic means (crossbreeding, selection, and biotechnology). Breed changes and crossbreeding influence the value of milk, but the choice of breed is usually dominated by attributes other than milk composition. Responses to within-breed selection are influenced by the emphasis placed on milk components relative to other animal attributes. The relative economic emphasis among the traits in the objective, and the genetic and environmental relationships between measured performance attributes will influence the rate of progress in milk quality, milk value and farm profit. Transgenic modification of the bovine genome offers the possibility of quantum shifts in milk characteristics but requires further research, education and testing in order to gain consumer acceptance. The manufacture of high-value dairy products for specific markets will likely require the segregation of milks from different farms. The long-term nature of genetic improvement dictates that today`s vision shared by producers, processors and AB companies must be in concert with future needs of consumers if real opportunities are to be realised.

Genetics modification to create novel high quality forages - Roberts NJ; Hancock KR; Woodfield DR (Proceedings of the New Zealand Society of Animal Production, 2002)
Genetic improvements in forage quality can lead to improvements in animal performance. We outline two approaches aimed at generating high quality forages that increase the energy available to the ruminant. These include the heterologous expression of fructan biosynthesis genes in the leaf to produce high molecular weight soluble carbohydrate and the modification of the expression pattern of endogenous triacylglyceride biosynthesis genes to produce triacylglycerides in the leaf. In vitro experiments demonstrated the potential of the rumen to digest fructans with either b(2-6) or b(2-1) linkages, furthermore both in vitro and in vivo experiments showed that fructan reduced the concentration of NH3 in the rumen. We discuss the advantages of raising the lipid content of forage and the ramifications of expressing triacylglcyeride biosynthesis genes in the leaf. The expression of other genes that modify the quality of the fatty acids within triacylgycerol are also discussed briefly.

Giving consumers more reasons to drink milk - Haylock SJ (Proceedings of the New Zealand Society of Animal Production, 2002)
The options confronting consumers when choosing a milk product continue to expand. This is driven from the recognition that consumers have different needs and that milk is perhaps the best nutritional raw material that can be used to deliver a range of enhanced nutrition and health benefits. Products that target the needs of specific age groups, health concerns, or greater affordability, all give consumers greater justification for consuming milk. Similarly, the ever-increasing range of product formats, flavours and new products containing milk that are supported by emotive marketing campaigns will ensure that consumers continue to have plenty of justification for having that extra glass.

Growing grass and clover separately allows animals to sustain a high nutrient intake - Marotti DM; Cosgrove GP; Chapman DF; Parsons AJ; Egan AR; Anderson CB (Proceedings of the New Zealand Society of Animal Production, 2002)
White clover has high nutritive value but the proportion in mixed pasture and therefore the diet, is often low. Offering sheep ryegrass and clover growing side-by-side, for short periods, increases the proportion of clover in the diet and daily intake compared to a mixed pasture. This experiment tested whether sheep offered ryegrass and clover side-by-side could sustain a high proportion of clover in their diet and a high daily intake, compared with sheep grazing ryegrass alone, clover alone and ryegrass and white clover growing as a mixed sward. Forty-eight dry, non-pregnant Romney ewes (56 ± 1.8kg live weight) were randomly allocated to four replicates (two spatial x two temporal) of each treatment (n=3) for 12 days. Average grazing time was 292 ± 16.2 min/day and did not differ significantly among treatments. Short-term intake rate on clover (5.0 g/min) was higher than ryegrass (3.5 g/min) (P=0.02). As a result, clover dominant diets supported higher daily intake (1.36 kg/d for clover alone vs. 1.08 kg/d for ryegrass alone). Sheep sustained a diet of 70% clover and 30% ryegrass, showing that predominance of clover in the diet was not a result of novelty. This improved daily intake would provide significant benefit to animal production systems and can be achieved simply by growing grass and clover separately.

Implementation of environmental regulations on-farm - Clark DA; Lambert MG (Proceedings of the New Zealand Society of Animal Production, 2002)
A case study of the consultative process concerning water clarity in Lake Taupo was used to identify the key elements required to reach consensus between land-owners, users and regulatory authorities. These elements included: the identification of all stakeholders; impacts at the farm level where individual behaviour change must occur; the scientific validity of data used and the decision support models available to assess biological and economic impacts. The importance of the consultative `process` itself and the need for sufficient time for this process to occur were other key elements. The Lake Taupo case study was then compared with the larger scale issue of greenhouse gas emissions (GHG) from New Zealand agriculture. We concluded that a much greater level of scientific uncertainty existed for the effect of GHG emissions on climate change than for Lake Taupo water clarity. This fact, coupled with the potentially much greater economic impacts on agriculture and individual farmers helped explain farmer reluctance to accept proposed solutions. Findings from the Lake Taupo study suggest the way forward in the GHG emission debate requires a major improvement in the underpinning science and a clearer understanding of the implications of GHG emission control at the farm scale. Mitigation options must consider both physical and financial inputs and outputs. The consultative process must involve farmers at policy, economic and science levels and be long enough to cover all issues.

Improved nutritional quality of animal products through manipulations of trace element and calcium status - Knowles SO; Lee J (Proceedings of the New Zealand Society of Animal Production, 2002)
Research on the requirements and metabolism of trace elements in grazing livestock is revealing new ways in which the nutritional status of people might be improved. Our understanding of how to manage the mineral status of cattle and sheep can create additional impact through enhancing the quality and value of milk and meat. For example, by optimising the familiar selenium and iodine supplementation strategies used to prevent deficiencies and maintain animal mineral requirements, we can tailor the element content of the resulting animal products. Simple Se and I supplementation produces commensurate increases in milk and meat, but the concentrations of calcium and iron are not so easily manipulated, so other smarter strategies are called for. For these four nutritionally essential elements, maximum concentration and bioavailability to humans is affected by age of animal, stage of lactation, plus element chemical form and distribution among the milk and meat fractions.

Improving animal performance using forage-based diets - Burke JL; Waghorn GC; Chaves AV (Proceedings of the New Zealand Society of Animal Production, 2002)
New Zealand livestock systems are based on ryegrass dominant pastures, but they are unable to maximise animal production. Limitations of ryegrass-based pastures are reviewed, and opportunities for using alternative forage species to complement pasture and improve animal production are discussed. Ryegrass pastures have low dry matter contents and high fibre concentrations which restrict feed intake so animal energy requirements are often not met. High crude protein (CP) concentrations in spring and rapid proteolysis in the rumen produces excess ammonia which must be excreted, whereas summer pastures contain insufficient CP. Chicory, red clover, lotus species, sulla, lucerne and maize silage are examples of forages that can complement ryegrass to improve animal performance. More information is needed to define digestion and fermentation of fresh forages in the rumen, but in vitro and in sacco techniques have been used to evaluate these parameters for grasses, legumes, herbs and silages. This information with feed composition data will be used in computer simulations to predict forage mixtures able to complement pasture at different times of the year. The challenge will be to complement the changing ryegrass pastures with other forages to improve animal welfare, productivity and profit.

Incidence and perceptions of cryptorchid lambs in 2000 - Tarbotton IS; Bray AR; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 2002)
A telephone survey of 400 randomly selected sheep farmers was undertaken to determine the incidence of ram, cryptorchid, and wether lambs in the New Zealand lamb flock in 2000. Respondents were asked why they choose to produce rams, cryptorchids or wethers and how willing they would be to change. The percentage (+/-5%) of male lambs left entire and made cryptorchids was similar at 39% and 41% respectively with the remaining 20% wethers. The primary reasons why farmers produced cryptorchids was to achieve good lamb growth rates and lean carcasses without having fertile male lambs. Published research reports support the perception of leanness relative to wether lambs but indicate that carcass weights are similar to those of ram and wether lambs and that some cryptorchids may be fertile. Secondary reasons given for producing cryptorchids were that they were cleaner and easier managed than ram lambs. Although the production of cryptorchids has declined in recent years, 71% of the farmers who currently produce them have a preference for this method and indicated unwillingness to change from this practice.

Incidence of mastitis among cows of different genogtypes in differing nutritional environments - Lacy-Hulbert SJ; Kolver ES; Williamson JH; Napper AR (Proceedings of the New Zealand Society of Animal Production, 2002)
Over three seasons (1998, 1999 and 2000) groups of Holstein-Friesian cows of New Zealand (NZ) or overseas (OS) origin were monitored for mastitis when managed in two contrasting systems. Cows were fed either on pasture or total mixed ration (TMR) with cows on TMR confined to small loafing paddocks or a concrete feedpad. All quarters were sampled for bacteriology at calving, at dry off, in mid and late lactation and when clinical mastitis was detected. Individual cow somatic cell counts (SCC) were determined weekly throughout lactation. In 1998, there was no difference in incidence of clinical mastitis but in later seasons, cows on TMR experienced significantly more clinical, and sub-clinical mastitis, than cows on pasture, probably reflecting differences in bacterial challenge within the environment. Genotype differences were less evident compared to dietary effects. Compared to NZ cows, OS cows experienced more sub-clinical infections in 1998 and more clinical infections in 1999 whilst in 2000, genotype effects were confounded by diet. Seasonal SCC was higher for OS cows in 1999 and 2000, reflecting differences in incidence of sub-clinical mastitis among treatment groups. Despite the strong influence of environment on mastitis incidence, genotype differences were detectable between NZ and OS cows.

Increased milk lactic acid concentration is an early indicator of mastitis - Farr VC; Prosser CG; Nicholas GD; Lee J; Hart AL; Davis SR (Proceedings of the New Zealand Society of Animal Production, 2002)
The cost of mastitis to the dairy industry in NZ is substantial, with economic losses accruing from antibiotic costs, acute and chronic milk yield losses and reduced longevity of susceptible cows. Early detection and treatment of mastitis is a critical factor in reducing the severity of the infection and tissue damage within the udder (Douglas et al., 1997). However, increases in labour productivity are reducing contact time with cows, making early detection of mastitis increasingly difficult. In particular, the development of robotic milking equipment has highlighted the need for remote detection of mastitis. Apart from visual examination of fore-milk, somatic cell count (SCC) is used as the standard marker of milk quality. An increase in bulk milk SCC or a high SCC at herd test is used to diagnose new infections. However, one of the most widely used methods for cow-side or automated in-line testing for mastitis is the detection of changes in electrical conductivity of milk. This approach has several problems, not least of which is the limited accuracy of the method (see Woolford et al., 1998) and the relatively high cost of sensors (claws). The following study was undertaken as part of a screen of a number of potential markers in milk which could be used to indicate mastitis …

Induced cryptorchidism no solution to the rut - Nicol AM; Keeley MJ (Proceedings of the New Zealand Society of Animal Production, 2002)
Two experiments were made to determine if induced cryptorchidism (short-scrotum) would modify behaviour and reduce liveweight loss during the rut without affecting subsequent velvet production. In the first experiment, groups (n = 10) of entire and induced cryptorchid mixed-age stags were used in a behaviour study in consecutive years. In mid-January, stags in the cryptorchid group were sedated with xylazine, and their scrotum shortened as much as possible (two thirds of the length) by the application of two standard lamb castration rings. Behavioural observations made during the rut showed significant (P< 0.05) reductions in the incidence of roaring, chasing and pacing in the cryptorchid group. In a larger scale experiment on six commercial properties, the live weight and condition score change over the rut, and subsequent velvet production was compared on 100 entire and a similar number of cryptorchid stags. Average liveweight loss during the rut (Feb-June) was 17 kg with no significant difference between entire and cryptorchid stags. There was no difference in mean live weight of the two groups the following Sept/Oct and the average velvet weight was 2.48 and 2.41 kg for the entire and cryptorchid stags respectively (P>0.05). Although induced cryptorchidism influenced stag behaviour during the rut, this was not reflected in reduced live weight or condition score loss during this period.

Influence of milk cytokines on mammary production of nitric oxide - Turner S-A; MacKenzie DDS; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 2002)
Cytokines such as interferon-gamma (IFN-g) can stimulate the production of nitric oxide (NO) from mammary epithelial cells, which in turn may play a role in intramammary defence of the mammary gland. In this study, comparisons were made with the production of IFN-g stimulated NO from Comma-D cells (murine mammary epithelial cell line) and explants of mammary tissue collected from both pregnant (day 12-14 of gestation) and lactating (day 12-14 postpartum) rats. Response to IFN-g was measured as the production of nitrate and nitrite (NOx) in the culture medium. Comma-D cells and explants of mammary tissue from pregnant and lactating rats responded to treatment with 250 U/ml IFN-g with an increase in NOx of 5231, 300 and 373% respectively. The response to IFN-y was lower (P<0.001) in explants than in Comma-D cells. Inclusion of nitric oxide synthase (NOS) inhibitors aminoguanidine (100 mM) and Nw-nitro-L-arginine (1 mM) in the culture medium reduced NOx production by the Comma-D cells to 31 and 19% of stimulated activity respectively. This suggests that Comma-D cells are a good model for investigating effects of cytokines on mammary epithelial cell production of NO, and may also provide a useful means of screening other milk bioactives for their potential role in intramammary defence.

An innovative farm system combining automated milking with grazing - Jago J; Copeman P; Bright K; McLean D; Ohnstad I; Woolford M (Proceedings of the New Zealand Society of Animal Production, 2002)
The harvesting of raw milk for the New Zealand dairy industry is a labour intensive process. Technology to completely automate the milk-harvesting process has been developed in Europe and is operating on an increasing number of commercial farms in several countries. A research programme has been established at Dexcel to develop innovative pasture-based farm systems utilising existing automated milking technology. A new farm layout was designed and implemented on a 10 ha farmlet. The land was radially subdivided into eight paddocks leading to a central collection area. A 200-m two-way race extended between the collection area and a small waiting yard adjoining a Fullwood Merlin automated milking system (AMS). Water was only available in the central collection area, the holding yard and as cows exited the AMS. Cows had access to the AMS for 24h/day where they received a maximum of 2kg concentrate/ 24h. A herd of 41 mixed-age cows was milked in the farm system. Data for a 14-day period in October when cows had settled into the system were analysed. Cows voluntarily visited the AMS 2.7 times/24h and were milked 2.3 times/24h. Visits were distributed over 24h with the lowest number of visits occurring between 0330 and 0600. Cows demonstrated remarkable adaptability in a distributed AMS and there appears to be considerable potential for AMS within New Zealand’s pasture-based farming system.

Johne's disease in deer - prospects for control - Mackintosh CG (Proceedings of the New Zealand Society of Animal Production, 2002)
This paper summarises current knowledge of Johne`s disease (JD) in farmed deer in New Zealand and discusses prevention and control options. JD in deer is caused by "bovine strains" and "ovine strains" of Mycobacterium avium subsp. paratuberculosis. Two clinical syndromes are recognised; sporadic cases in mixed age deer and serious outbreaks, affecting up to 15% of groups, in 8 to 15 month old deer. Over 300 deer farms are known to be infected and the number is increasing. Studies have shown that the gel diffusion test is the most reliable test for confirming JD in clinically affected deer. However, none of the currently available serological or cell-mediated immunological tests is sufficiently sensitive or specific for detecting subclinical paratuberculosis in deer. Farms free of JD should prevent its introduction. Control options on infected deer farms are limited to management options: culling affected stock, culling test-positive animals or depopulation and restocking after 2 years. Vaccination may be the most cost-effective long term control option if a suitable vaccine can be developed. A voluntary market assurance programme for deer farms has been proposed, but implementation depends on the benefits to farmers and on the national deer farm JD prevalence being low enough to warrant it.