Dagginess and flystrike in lambs grazed on Lotus corniculatus or ryegrass - Leathwick DM; Atkinson DS (Proceedings of the New Zealand Society of Animal Production, 1995)

Development of a management system to intensify and increase beef production in a range suckler herd in Israel - 'the Amaziah project' - Lehrer AR; Kahn HE; Kreitzer J; Gacitua H; Mizrachi Y; Kali J (Proceedings of the New Zealand Society of Animal Production, 1995)
Repeated sheep treatment with the anthelmintic drug benzimidazole (BZ) resulted in selection of genetically benzimidazole-resistant (BZ-R) nematodes, which code for a specific allele of isotype 1Beta-tubulin. The presence of this allele was tested in the Waikato ovine nematode, using an allele specific PCR. Two isotype allele specific oligomers for O. circumcincta (O.c.) Beta-tubulin gene were designed. The last base at the 3

Differences in propensity of wool to develop yellow discolouration in flocks of Perendale sheep selected for and against - Reid TC; Botica KJ; Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1995)
CONFIRM is a recently developed test kit for verifying pregnancy in dairy cows on the basis of the concentration of oestrone sulphate (OS) measured in a milk sample taken at least 120 days after mating/insemination. In this study, the performance of CONFIRM was evaluated using milk samples from non-pregnant cows returning a

Discovery of the Inverdale gene (FecX) - Davis GH; McEwan JC; Fennessy PF; Dodds KG (Proceedings of the New Zealand Society of Animal Production, 1995)
Selection for ovulation rate in a screened prolific flock identified a prolific family of Romneys in 1984 that descended from one ewe, and progeny tests for her male descendants carried out from 1985 to 1990 indicated the presence of a major gene (Inverdale) on the X- chromosome. One copy of the gene increases ovulation rate by about 1.0 and litter size by about 0.6. However, research in 1991 found that ewes with two copies of the gene have small non-functional 'streak' ovaries and are infertile. Many of these infertile ewes develop tumour-like structures on their ovaries and these are currently the subject of intensive research. In 1993 a prolific Romney flock in Tokoroa, with no known connection with A281, was also found to have the Inverdale gene. The place of the Inverdale gene in industry will be to increase prolificacy in ewe flocks mated to terminal sires, and a research programme has been established to identify a genetic market for ram breeders.

Early lactation response of dairy cows to pasture under two different nitrogen fertiliser regimes - Mackle TR; Parr CR; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1995)
Near-infrared (1100-2500 nm) reflectance spectra were measured on 128 beef ribeye samples using a scanning monochromometer and calibrated against standard laboratory analysis to develop a rapid method for measuring intramuscular fat of beef. A pilot run was conducted on 38 frozen ribeye samples, ranging in fat content from 94 to 325g/kg dry weight, to evaluate sample preparation methods (frozen slices, thawed slices, coarse mince. After scanning of subsamples, fat content of the sample was then measured using Soxhlet extraction. Standard error of calibration (SEC) was 9g/kg dry weight for spectra collected from minced samples compared to 25g/kg for frozen slices and 15g/kg for thawed slices. A second set of 90 frozen ribeye samples (fat content range 56-305 g/kg dry weight) was used to test and improve this calibration, using 3 subsamples of minced beef per sample. The ability of the initial calibration equation to predict fat content of these samples was poor. A more robust calibration was then attempted by pooling the data from the two sets. The SEC of this extended set was 16 g/kg dry weight (10% of the sample set mean) and the multiple R2 of calibration was 0.92. The standard error of prediction for new samples was estimated from internal cross-validation runs as 19 g/kg. Prediction of fat content of an independent validation set of 24 samples had a standard error of 20 g/kg dry weight. Analysis of the calibration results suggested that a major source of error in the calibration was hererogeneity between subsamples, with the standard deviation of prediction of different subsamples from the same ribeye being larger than the standard error of cross validation. These results indicate that Near-Infrared reflectance spectroscopy may provide a rapid objective method for estimating intramuscular fat of beef.

Effect of allowance and the rate of adaptation of weaned calves to two brassica types - Muir PD; Wallace GJ; Slay MWA (Proceedings of the New Zealand Society of Animal Production, 1995)
Groups of 10 Friesian bull calves averaging 142 kg were offered Winfred forage brassica (62% leaf) at allowances of 3, 6, 9, 12 or 15% of bodyweight (BW) for 6 weeks. Similarly, groups of 8 Friesian bull calves averaging 150 kg were offered Wairoa forage brassica (67% leaf) at allowances of 3, 5, 7, 9 and 12 % of bodyweight. Calves were weighted weekly and offered fresh allowances each week. The two experiments were conducted between January and March of the same year but were not run concurrently. There was a significant effect (P<0.01) of allowance on liveweight gain for calves offered Winfred, with calves on the lowest allowance (3% of BW) growing at 0.90 kg/day, compared to 1.20 kg/day for calves grazing the other four allowances. Calves grazing the low allowance (3% of BW) utilised 77% of the total crop, but only 43% of the stem. On the other hand, calves grazing the low allowance of Wairoa utilised 90% of the total crop and 72% of the stem without suffering a liveweight penalty. There was no effect of allowance of Wairoa on calf growth rate and overall, calves on Wairoa grew at an average of 1.03 kg/day. Choice of a leafy type of brassica maybe important if the objective is a high degree of utilisation coupled with good animal performance. Alternatively, on

The effect of anthelmintic treatment of ewes during pregnancy - Familton AS; McAnulty RW; Thompson KF; Sedcole JR (Proceedings of the New Zealand Society of Animal Production, 1995)

Effect of continuous stocking of breeding ewes at different sward surface heights during the late summer-autumn on herbage intake and productivity - Panggabean AU; Morris ST; Parker WJ; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1995)
This study aimed to raise GnRH antibodies in young bulls (immunocastration) and determine the subsequent effect on behaviour, sexual development, carcass characteristics and meat quality. Thirty Friesian bull calves were assigned to one of three groups balanced by liveweight (control bulls, immunocastrates and steers). At nine months of age (Day 0) immunocastrates were vaccinated against GnRH (Vaxstrate) and boosted one month later (Day 31). Following immunisation there was a rise in GnRH antibody titre and a decrease in testosterone. Control animals gained significantly more weight than immunocastrates and steers in the first 157 days. Overall there was no difference in weight gain between controls and immunocastrates. Mean scrotal diameter of immunocastrates decreased from Day 31 to Day 110 and then rose to reach a diameter similar to those of the control bulls by Day 322. Leg wear scores were lower for treated animals compared to controls until Day 230 of the trial, although these differences were not significant. Immunocastrates had a significantly higher mean ultimate pH than both control bulls and steers. Bulls were significantly leaner than immunocastrates, and both groups were leaner than steers.

Effect of control of internal parasitism on productivity of Merino breeding ewes - Sumner RMW; Watson TG; Hosking BC (Proceedings of the New Zealand Society of Animal Production, 1995)

Effect of diluent type and storage time on the pregnancy rate of ewes inseminated laparoscopically with chilled ram semen - Smith JF; Parr J; Murray G; Oliver JE; Beaumont S; Upreti GC (Proceedings of the New Zealand Society of Animal Production, 1995)
Five trials involving 879 ewes were conducted in November, December 1993, February, March and April 1994. Ewes were synchronised with CIDR

The effect of immunological castration on behaviour and growth of young bulls - Jago JG; Lasenby RR; Trigg TE; Claxton PD; Matthews LR; Bass JJ (Proceedings of the New Zealand Society of Animal Production, 1995)

Effect of level of nutrition on age of puberty and reproductive performance of Friesian heifers - Penno JW; Macmillan KL; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1995)
Muscle proteolysis is controlled by a number of enzyme systems. The reported effects of the calcium dependent proteinases (or calpains) on myofibrillar structure have led to the speculation that this enzyme system may have an important role in regulating muscle growth and the post mortem ageing process. Although at present there is no clear economic incentive, meat quality has to be taken into account since the white meats of poultry and pork are out competing the traditional red meats of lamb and beef. Meat quality attributes may largely depend on slaughtering and post mortem ageing regimes, however, variability also originates from the biological characteristics of muscles which are undoubtedly environmentally and genetically controlled. The aim of the present experiment is to examine the effect of genotype, nutrition and their interactions on the calpain system. Progeny from 3 sire breeds (Texel, Fat Southdowns and Lean Southdowns) were weaned in December and placed onto one of two growth paths until May (high (H) or low (L) rate of gain), from May until July these groups were further divided into groups HH, HL, LL and LH. Animals were slaughtered at the Ruakura commercial slaughter facility, samples for calpain analysis were taken from the distal portion of the longissimus dorsi of the animal within 20 minutes of slaughter. The assays were performed as outlined by Dobbie et al., (1995). Calpain-I differed significantly (p<0.05) between genotype (Texel 0.57 SDFat 0.50 SD Lean 0.41 U/g (SED 0.060). Calpastatin was significantly (P<0.05) affected by plane of nutrition immediately after weaning. (H:2.61 L:2.35 U/g SED 0.126). The results taken together suggest that complex physiological interactions exist between genotype and nutrition with respect to the calpain system.

Effect of Monensin capsules on blood metabolites near calving in twin- pregnant and single-pregnant beef cows - McMillan WH; Oakley AP; Hewitt W (Proceedings of the New Zealand Society of Animal Production, 1995)
The aim of this study was to test the hypothesis that Rumensin capsules administered during late pregnancy would have equally beneficial effects in single- and twin-pregnant beef cows, on circulating levels of beta- hydroxy butyrate (BOH), magnesium (Mg) and glucose. Forty cows, half of which were twin pregnant, were treated with either a single Rumensin capsule from a mean of 66 d prior to calving, or remained as untreated controls. Plasma samples were taken on d66, 38, 23, 13 and 5 prior to calving. Rumensin lowered BOH concentration by the second sampling time (0.53 vs. 0.765 mmol/l, P<0.01) and maintained this concentration until calving. Rumensin was without effect on Mg or glucose concentrations. The effects of Rumensin were additive to those of pregnancy status (twin vs. single) for all three metabolites thus confirming our hypothesis. Rumensin may therefore be useful in the late pregnancy management of twin pregnant cows.

Effect of nitrogen fertiliser and summer rotation length on milk production in a dry Waikato summer. - Penno JW; Bryant AM; Carter WA; MacDonald KA (Proceedings of the New Zealand Society of Animal Production, 1995)
Muscling is considered important by the New Zealand meat industry. As Texel cross lambs contain more muscle than most other sheep genotypes, a muscling trial was undertaken using Texel and Oxford cross and High Romney mixed sex lambs. Eighteen lambs were slaughtered from each breed. The muscle, bone, subcutaneous and intermuscular fat were separated from the leg and shoulder of the 54 right sides. The leg comprised on average 64.4% lean in the High Romneys, 66.2% in the Oxford cross lambs and 67.4% in the Texel cross lambs (p<0.05). The corresponding figure for shoulder lean 58.8% (Romney), 59.9% (Oxford) and 62.1 (Texel) (p<0.05). The eye muscle area (cm2) for these lambs was 9.8 (Romney), 11.0 (Oxford) and 11.7 (Texel). The muscle:bone ratio (weights) for 4 leg muscles to the femur were 7.0 for the Romneys, 7.6 for the Oxford and 8.3 for the Texel cross lambs (p<0.10). Only 2 non Texel lambs were classed E under the European classification system.

Effect of once daily milking (ODM) on enzyme activities in the bovine mammary gland - Farr VC; Stelwagen K; Kerr MA; Davis SR; Eichler SJ (Proceedings of the New Zealand Society of Animal Production, 1995)
Maintenance diets containing two levels of energy (9.6 v. 11.5 MJME per kg DM) and two levels of protein (10.7 v.21.7 g nitrogen per kg DM) were fed to four groups, each of ten Romney (five low and five high staple tenacity) and four Drysdale yearling rams, for six weeks from mid March. Protein supplementation increased protein intake by 114% (P<0.001). It increased clean wool growth in the treatment period (6.2 v. 10.2 g.um- 2.d-1, P<0.001), more so in Drysdales than Romneys (89 v. 46%; P<0.001). It also increased mean fibre diameter (38.1 v. 34.3 um, P<0.001) without changing the proportion of fibre that was medullated. Responses to the nutrient supplements were similar in low and high staple tenacity Romney rams. It is concluded that during the photoperiod-induced decline in wool growth in autumn, sheep on a maintenance diet responded to the increase in dietary protein with an increase in the volume of fibre and volume of keratin produced with no net change in the proportion of fibre medullated.

Effect of once-daily milking and bovine somatropin administration in Friesian cows on milk protease activity - Stelwagen K; Whyte JH; Zavizon B; Prosser CG; Davis SR; Farr VC; Politis I (Proceedings of the New Zealand Society of Animal Production, 1995)
Samples of wool from Perendale hoggets born at Whatawhata Research Centre in 1989 from ewes selected for and against loose wool bulk were tested for propensity to yellow. After storage in a laboratory for two years, wool from the high bulk line was significantly more yellow than wool from low bulk line. When the greasy wool was incubated at 40 degrees and 100% relative humidity, differences in all three tristimulus values between high and low bulk wool were significant. Tristimulus Y and Z decreased and Y minus Z increased when clean wool samples were subjected to more extreme challenges similar to those which may occur during processing. These changes did not affect the differences in colour between the selection lines. These results suggest that management changes may be required to restrict yellowing of high bulk wool during growth and storage. Simultaneous selection for reduced propensity to yellow and increased bulk may reduce the genetic progress attainable in either characteristic.

The effect of peramine ingestion in pen-fed lambs - Pownall DB; Familton AS; Field RJ; Fletcher LR; Lane GA (Proceedings of the New Zealand Society of Animal Production, 1995)
Little research has been done on within breed differences in seasonality of reproduction in rams. We took 16 Dorset x Romney rams (8 BV+ and 8 BV-, selected on the basis of their breeding value for date of lambing derived for the lambing performance of their female relatives). These rams were housed indoors under natural light conditions and fed a ration of pellets and hay. Semen samples, testis diameter and body weight measurements were taken weekly. Blood samples were taken monthly (every 20mins for 26hrs, and then every 10mins for a further 4hrs following a 1 ml IV injection of 0.001 mg GnRH). Samples were assayed for oLH and oFSH. The trial ran from September 1993 to August 1994. More BV- (early lambing group) rams (70% vs 25%) produced ejaculates in the first 3 months of the trial. The BV- rams had significantly (P<0.001) lower ejaculate volumes than the BV+ rams with both showing significant (P<0.001) seasonal changes. There were significant (P<0.01) seasonal effects on semen concentration with a January maximum of 6300 x 10 6 sperm/ml and a minimum in July of 3350 x 10 6 sperm/ml. There was a seasonal effect on testis diameter (55mm in Dec-Feb and 38mm in July). There was a significant (P<0.05) seasonal shift in live weight between Feb-Apr (70kg) and July 58kg). There was significant (P<0.01) seasonal effect on basal LH levels and LH pulse frequency, but there were no detectable BV effects. The BV- rams had greater pulse amplitude and longer durations of peaks than did the BV+ animals. LH response to GnRH was significantly different only in Nov (BV- rams showed greater area under the curve 162

The effect of season and Beta-lactoglobulin phenotype on milk composition - Hill JP; Paterson GR; Lowe R; Wakelin M (Proceedings of the New Zealand Society of Animal Production, 1995)
128 carpet wool ewes, Romneys and Merinos of between 12 and 30 months of age, were set stocked for 13 months on a property at Oberon NSW. Live weights (LW) for Carpetmasters, Drysdales, Romneys and Tukidales were similar with Elliottdales being slightly lighter and the Merinos lighter again, giving rise to significant breed effects for maximum live weight (LW MAX) and minimum live weight (LW MIN). Wool growth (WG) of each breed was similar during winter, with significant differences between breeds appearing during summer. Breed had a significant effect on amplitude of live weight (LW AMP) and wool growth (WG AMP). There is a strong positive correlation between LW MAX and LW MIN and negative correlations between LW MIN and LW AMP, and minimum wool growth (WG MIN) and WG AMP. Regression analysis for predicting WG from LW and change in LW was unsuccessful with low R2(%) values especially during winter. It appears that nutritional influence on WG during winter may be minimal.

Effect of selection for early lambing on the expression of hogget oestrus activity - Smith JF; Parr J; Murray G; Harris C; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1995)
The effect of grazing parasitised ewe lambs on herbages with and without condensed tannins (CT

Effect of selection for early lambing performance on the seasonal patterns of gonadotrophin levels; response to GnRH and semen characteristics - Brewer JC; Briggs RM; Parr J; Wilkins RJ; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1995)

The effect of six herbages on liveweight gain, wool growth and faecal egg count of parasitised ewe lambs - Robertson HA; Niezen JH; Waghorn GC; Charleston WAG; Jinlong M (Proceedings of the New Zealand Society of Animal Production, 1995)

The effect of stocking rate and breed on the period of postpartum anoestrum in grazing dairy cattle - McDougall S; Burke CR; Williamson NB; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1995)
The effects of stocking rate (low, L; and high, H), breed (Jersey, J; and Friesian, F) and age (2, 3, >3 years old) on the intervals from calving to first ovulation and to first oestrus were assessed in pasture grazed dairy cattle using a 2 x 2 design. Cows in the FH herd had longer intervals from calving to first postpartum ovulation (C-ovn1; 49.2 vs 24.7, 31.1 and 29.4 days) and C-hl (47.1 vs 32.5 days) intervals than older cows, with 3 year old cows intermediate. The high stocking rate herds had reduced CS, liveweight and milk production compared to the low stocking rate herds. Condition score and milksolids production were inversely related to the C-ovnl and/or C-hl intervals. Increased stocking rates were associated with longer periods of postpartum anoestrum.

The effect on incidence of bloat of changing pasture herbage mass and species - Carruthers VR (Proceedings of the New Zealand Society of Animal Production, 1995)
The study involved 128 animals (19 Carpetmasters, 20 Drysdales, 19 Elliottdales, 20 Merinos, 23 Romneys and 27 Tukidales) maintained on improved pastures at Oberon, on the central tablelands of NSW. For the intake measurements, animals were stratified on liveweight into five groups within breed, and one animal selected from each group at random for dozing with controlled-release alkane capsules. The intake of Romneys (1.30 kgOM/day), Merinos (1.20) and Tukidales (1.18) was significantly (P<0.05) higher than that of Carpetmasters (0.98), Drysdales (0.78) and Elliottdales (0.80). There was no significant interaction between breed and season, with all breeds having a lower (P<0.01) intake in July (0.63) kgOM/d) than February (1.43 kgOM/d). When the intakes were expressed in terms of metabolic liveweight, there was again a highly significant difference between the intake in February and July (0.078 and 0.040 kgOM/g/LW0.75, respectively). On a metabolic liveweight basis breed differences also still existed, with Merinos (0.082) having higher (P<0.05) intakes than the other breeds.

Effects of breed and calving liveweight on postpartum ovarian activity in pasture-fed dairy heifers - Burke CR; McDougall S; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1995)
There is little information available on the muscle biology of deer and how this affects meat quality. The reported effects of the calcium dependent protease system (calpains and their inhibitor calpastatin) on protein turnover in vivo and myofibrillar structure posts mortem suggest it may have a pivotal role in regulating muscle growth and meat tenderisation. This study examines inter-muscle variation in the calpain system under two physiological conditions in red deer and its relation to meat tenderness. Nine muscle samples from 3 stags in rut (IR) and 3 out of rut (OR), were processed for calpain and calpastatin analysis within 20 minutes of slaughter. Tenderness of aged muscles was determined by measurement of ultimate shear force. The majority of the inter-muscle differences in the calpain system were associated with calpastatin activity. A positive relationship between muscle calpastatin levels and meat ultimate shear force was found.

Effects of genotype and nutrition on sheep carcass fat and eye muscle development between weaning and 14 months of age - Binnie DB; Clarke JN; Clayton JB; Mowat CM; Purchas RW (Proceedings of the New Zealand Society of Animal Production, 1995)
Although several studies have implicated cortisol in the control of body composition in sheep, the precise mechanisms are unclear. Cortisol basal concentration and response to an ACTH challenge was studied in Coopworth wethers selected for (Fat) or against (Lean) fatness in both the fed and 48 hour fasted states at two stages (15 and 33 weeks). The aim was to investigate whether fasting, age or genotype would influence cortisol secretory parameters. Mean basal cortisol concentration was higher for fasted than fed lambs (13.6 versus 8.9 ng/ml, p<0.001), but did not differ significantly with genotype or overall stage of development. Maximal cortisol response to ACTH was greater for the fat than the lean genotype, at both 15 weeks (86.3 versus 65.3 ng/ml, p<0.01) and 33 weeks (108.2 versus 91.1 ng/ml, p<0.01) of age. Maximal cortisol response was also significantly greater with fasting and increasing age, but the effect of fasting on cortisol increase was greater at 15 than 33 weeks of age. Clearance of cortisol was significantly slower after fasting, but unaffected (p>0.05) by genotype and development. Basal cortisol concentrations was not associated with differences in body composition between the fat and lean genotypes. However the larger maximal response in the fat genotype may indicate that the adrenal gland plays a role in determining body composition.

Effects of induced parturition on mammary function - McFadden TB; Verkerk GA; Clark BA; Hovey RC; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1995)
Four 6.4 ha farmlets each stocked with 24 high genetic merit Friesian cows were used to determine the effect of nitrogen fertiliser (N), and a long summer grazing rotation on pasture and milk production in summer. Treatments were 0 )-N) or 50 kg N/ha (+N) in December, January and March and a 16 day (16) or 40 day (40) rotation. Treatments started 15 December, following a two week uniformity period, and ran until 29 April. On the 16 and 40 day rotations N increased net herbage accumulation by 0.8 t DM/ha, and milksolids (MS) production by 92 and 38 kg/ha respectively. Across both nitrogen treatments, the 40 day rotation increased net herbage accumulation by 1.7 t DM/ha. The MS production was 39kg/ha greater on the -N40 than the -N16 treatment whereas that of the +N16 and +N40 did not differ significantly. The N and long rotation treatments also resulted in higher average herbage mass and cow condition at the end of the experimental period. It is concluded that N in early summer and a long summer rotation are useful management practices to reduce the effects of summer dry periods.

Elucidation of the genetic nature of the Inverdale gene (FecX): Segregation with a twist - Dodds KG; Davis GH; McEwan JC; Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1995)
A major gene, affecting a quantitative trait in farmed livestock, is usually detected by observing segregation of the gene within families such as half-sib sire families. In the case of the Inverdale, a maternal family was observed to contain some highly prolific ewes. Progeny testing of four rams from this family revealed two rams with prolific progeny, but segregation amongst these progeny was not apparent. The data appeared to be consistent with the hypothesis of an X-linked major gene, but were not conclusive. A further progeny test involving six sons and five maternal grandsons of a putative Inverdale ram was undertaken. Three of the maternal grandsons but no sons had prolific daughters, confirming the X-linked hypothesis. Further major gene searches should consider X-linked as well as other modes of inheritance. The mode of inheritance, and effect of one and two copies of the Inverdale gene, have important consequences for its use in research and production.

Endocrine manipulation of the pregnant animal and growth of her offspring: a review - Spencer GSG (Proceedings of the New Zealand Society of Animal Production, 1995)
The Stockpol model was designed for decision support on New Zealand sheep and beef cattle farms. It indicates the biological feasibility of a livestockj system and provides the opportunity for users to test alternative livestock policies. An evaluation of the Stockpol model was made using 44 data sets from farmlet trials at Gore, Ballantrae and Whatawhata Research Centres and data from Massey University

Establishing a flock for gene mapping in wool traits - Wuliji T; Montgomery GM; Dodds KG; Andrews RN; Beattie AE; Turner PR; Rogers J (Proceedings of the New Zealand Society of Animal Production, 1995)
A gene mapping flock for wool traits was established by backcrossing of Merino cross Romney (F1) to both parental breeds. The objectives for this flock were to investigate the segregation of wool and skin characteristics in crosses between the Merino and Romney and to investigate methods for the analysis of genetic markers and quantitative trait loci. Analysis of Merino backcross animals showed no evidence of major genes segregating for any of the wool traits studied. The analysis estimated a finite number of genes affecting fibre diameter and bulk. A genetic marker study of these family groups may provide more powerful analysis for the presence of genes affecting wool traits that may be segregating in these crosses.

Estimated pasture intake and cow output of single and twin calving beef breeding cows - Bown MD; Clayton JB; McMillan WH; Smeaton DC (Proceedings of the New Zealand Society of Animal Production, 1995)
Thirty-eight adult Merino breeding ewes were drenched with Ivomec and given a controlled release anthelmintic (benzimidazole) capsule in August 1992 and December 1993. Mean FEC in the Untreated group peaked over lambing at 600epg in 1992 and 800epg in 1993. Mean FEC in the Treated group remained below 50epg during the active period of the capsule. The Treated ewes had a higher survival rate, were heavier, grew more wool from late July 1993 and weaned more and heavier lambs in 1993 than the Untreated ewes. At a mean Merino wool price of 500c/kg greasy, returns from the increased wool production more than equates with the anthelmintic treatment cost. Increased returns would be gained from improve ewe survival and increased lamb production.

Evaluation of 'CONFIRM' as a method to verify pregnancy in dairy cows - Henderson KM; Camberis M; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1995)
A total of 24 mature rams and ewes (>2.5 yrs) from a line selected for high backfat thickness and an unselected control line were used to investigate the relationship between maintenance efficiency and body composition in mature sheep. Over a 6 week period the sheep were fed daily a pelleted ration at levels to maintain liveweight. At the end of this period the weights of total fat, carcass lean, viscera and of the empty body (fleece free) were estimated from X-ray computed tomographic images. After adjustment for empty body weight the control line required 5% more feed to maintain liveweight (P<0.05) than sheep from the fat line and males required 19% more feed (P0.05) than females. After adjustment for differences in either total fat or carcass lean weight, there were no significant difference (P>0.05) in feed requirements between the lines. This indicated that although a genetic change in body composition did alter maintenance feed requirements at maturity, the efficiency of maintaining a unit weight of either fat or carcass lean remained the same. After adjustment for differences in total fat and carcass lean weight, rams still required 11% more feed than ewes to maintain liveweight. Adjusting for visceral weight had no effect on feed requirements to maintain the mature sheep. It was proposed that differences in the turnover rates of adipose tissue or carcass lean contributes to the higher maintenance feed cost observed for the mature ram.

Evaluation of large scale trapping of flies as a means of reducing the incidence of flystrike in lambs - Atkinson DS; Leathwick DM (Proceedings of the New Zealand Society of Animal Production, 1995)

Evaluation of muscling using Texel and Oxford cross Romney and Hight Romney lambs - Kirton AH; Mercer GJK; Clarke JN; Dobbie JL; Duganzich DM; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 1995)
Selection for out-of-season breeding ability could be enhanced if an early indication of the trait was available. The onset of hogget oestrus has been proposed as such a trait and has been examined for 362 ewe progeny coming from early and late-lambing selection lines over 3 years. In each year the early lambing (BV-) hoggets had an earlier (P<0.05) mean date of onset of oestrus than the hoggets from the late-lambing (BV+) line. In 1992 and 1993 this effect was confounded by the season of birth such that nearly all the BV- animals were autumn born (AB) and the BV+ animals born in the spring (SB). In 1993 animals from both lines were produced in both seasons. Their mean day of first oestrus in 1994 (expressed as day of year

An evaluation of the Stockpol model - Webby RW; McCall DG; Blanchard VJ (Proceedings of the New Zealand Society of Animal Production, 1995)
The potential of large scale bin trapping of flies as a means of reducing the incidence of flystrike was evaluated. Two 5 ha paddocks of similar soil type and pasture species composition, but more than 500 m apart, were used. From Nov. 16 to Dec. 24 flies were trapped in paddock 1 using four 2001 bin traps baited with sheep

Ewes for more dollars and flexibility - Walpole D (Proceedings of the New Zealand Society of Animal Production, 1995)
New Zealand's national lamb weaning percentage has hovered around 100% since 1960. This is a disappointing figure considering the number of sheep recording and performance analysis packages that are available to ram breeders. The present "average" NZ ewe probably drops about 1.20 lambs. Assuming 14% lamb losses from birth to weaning, and 6% ewes that die or are dry, each ewe mated weans about one lamb that grows at about 200g per day. One obvious way of improving these figures is to increase lambing percentage. For example, introducing 1/4 Finnish Landrace genes into the base flock has the potential to increase lamb drop by 20%. However, lamb growth rates must also be improved. Incorporating genetically superior milk producing breeds into the dam side as well will also increase lamb growth rates, resulting in lambs with the ability to grow at 250g per day or better. Ewes that produce 30% less wool than their contemporaries, but at the same time wean an extra 0.2 lambs that are 20% heavier than the flock average, can increase nett sheep-derived income by around 20%. The advantages are not just an immediate improvements in gross margins. Additional to this is the increased flexibility in management policies that result from having faster growing lambs that can be weaned earlier to provide better carcass weights or bigger replacements. This flexibility can be enhanced by introducing breeding programmes that utilise terminal sire breeds to further improve profitability. The major advantage of this more productive ewe is that it breaks the 100% lambing "poverty trap".

Faecal nematode egg counts and haematology in Perendale ewes near lambing - Watson TG; Hosking BC; Morris CA; Hurford AP (Proceedings of the New Zealand Society of Animal Production, 1995)

Feed requirements for maintenance of mature rams and ewes from lines selected for differences in body composition - Ball AJ; Thompson JM; Hinch GN; Fennessy PF; Blakely AR (Proceedings of the New Zealand Society of Animal Production, 1995)
Brief communication: no abstract supplied

Field scale evaluation of semen diluents for cervical AI in sheep: An attempt at technology transfer - Smith JF; Aspinall J; Oliver JE; Murray G; Smith JK; Upreti GC (Proceedings of the New Zealand Society of Animal Production, 1995)
No Abstract Supplied

Genetic markers in Inverdale (FecX) sheep - Galloway SM; Hanrahan V; Potts MP; Hill DF (Proceedings of the New Zealand Society of Animal Production, 1995)
The Inverdale gene (FecX) is carried on the sheep X-chromosome. Males carrying the Inverdale gene always pass a copy to their daughters, but not to their sons. Females carrying a single copy will pass the gene on to half of their offspring (both male and female). Progeny testing to determine which rams carry the gene, and which offspring have inherited, is time-consuming. Successful management of the Inverdale gene will require a simple, quick inexpensive test to distinguish carriers and non-carriers. A research programme has been initiated to develop a DNA test using DNA markers which will identify carrier animals at birth. Our initial strategy to find suitable markers was to build a map of genes and DNA markers on the sheep X-chromosome as a framework for looking for the Inverdale gene. We have determined the relative positions of twenty genes and DNA markers on the X-chromosome by looking at the pattern of inheritance of the X-chromosome markers in sheep pedigrees established in flocks at Invermay and Tuatapere. We estimate that 80% of the chromosome has been eliminated in our search to the Inverdale gene. Efforts are now directed towards identifying the particular region of DNA in which the Inverdale gene might lie. Suitable markers must be close enough to the Inverdale gene to be always inherited with Inverdale. Once such markers are identified a test can be developed to determine the Inverdale status of animals. Adaptation of the current techniques will enable DNA to be isolated from a few drops of blood, a mouth swab, or the ear tissue from a newborn animal.

Genetic parameters of lifetime wool production - Clarke JN; Dobbie JL; Hickey SM; Jones KR; Wrigglesworth AL (Proceedings of the New Zealand Society of Animal Production, 1995)
Heritabilities and genetic correlations were estimated from the selected and control lines of a 25-year selection experiment for hogget greasy fleece weight (GFW). The heritability of GFW was higher in the selected than the control line and in female hoggets (0.48) compared with males (0.32). Inter- age genetic correlations were less than unity, and higher in fleece weight selected animals. Average genetic correlations between hogget and adult records were higher in ewe than ram hoggets. Together these parameters gave co-heritability estimates (pooled across lines) for greasy hogget with clean adult ewe fleece weights of nearly half the average magnitude in males (0.21) compared with female (0.36). These results have important repercussions to the design of effective selection strategies for improvement of lifetime wool production.

Grazing behaviour of alpaca and sheep - Sharp P; Knight TW; Hodgson J (Proceedings of the New Zealand Society of Animal Production, 1995)
Differences between breeds in seasonal breeding activity have been linked to seasonal shifts in both LH levels and the magnitude of oestradiol negative feedback. Studies were undertaken to determine the endocrine differences in ewes of the same breed with high or low breeding values (BVs) for date of lambing. Forty-eight ewes (24BV- early lambing and 24BV + later lambing) were selected from the flocks and 16 ewes (8 of each BV class) were ovariectomized (ovx) and implanted with silastic implants containing oestradiol- 17Beta. All ewes were bled 2 x week for a 12 month period commencing in November to provide data on basal LB. The ovx ewes were subjected to rapid sampling (every 20 min for 24 h) using automated sampling equipment, on 5 occasions approximately 1 month after each equinox and solstice in that year and samples were analysed for LH pulse frequency. Basal LH levels showed a seasonal shift with the ovx ewes having a greater amplitude of change than the entire ewes. LH levels in the ovx ewes were lower in November to January, and higher in March, April, May and June; and lower again in August, September, October than in entire ewes. There was no evidence of a major difference in pattern due to BV. In the ovx ewes the values for the BV- animals tended to be lower than those for the BV+ ewes during March through July. At the initial rapid bleed no animals showed pulse activity. In April the BV- group had more pulses per 24 h (6.0 v 2.8). In July there was no difference in proportion having pulses (8/8) nor in the pulse frequency (5.3 v 5.6/24 h). In October the BV- animals had a higher pulse frequency (2.8 v 1.0), while the proportion of animals (3/8) exhibiting pulses was the same. More BV- ewes had pulses in January (6 v 3) and of those with pulses the BV- group had higher frequency (7.7 v 4.7). These data confirm the seasonal shifts in basal LH levels and in LH pulse frequency. Selection for earlier lambing had no effect on the pattern of basal levels. In the ovariectomized ewe the differences in LH pulse frequency due to BV detected in October and final bleed in January were not as marked as expected for the differences in the breeding activity of the two flocks but they confirm that differences in sensitivity to oestradiol 17Beta negative feedback are associated with differences in the onset of breeding season of ewes selected for earlier lambing within one breed. It would appear that selection for earlier lambing has disturbed the association between day length and LH pulse activity and the sensitivity of the pituitary to GnRH.

Growth Hormone (GH) secretory patterns in genetically lean and fat sheep - Francis SM; Veenvliet BA; Littlejohn RP; Stuart SK; Suttie JM (Proceedings of the New Zealand Society of Animal Production, 1995)
The pattern of GH secretion was studied in Coopworth sheep which have been selected for low (Lean) or high (Fat) ultrasonic backfat depth over 15 years. At each of two developmental stages (February and May) Lean and Fat ram lambs were fed ad libitum or fasted for 48 hours (n=6 per treatment). Animals were blood sampled via an indwelling jugular cannula every 10 minutes for six hours, then slaughtered and the pituitary glands removed and weighted. Mean GH was greater for Lean than Fat animals (2.82 versus 1.42 ng/ml, p<0.001), in February than in May (2.47 versus 1.62 ng/ml, p<0.001) and for fasted than fed animals (2.48 versus 1.62 ng/ml, p<0.001). Analysis of GH secretory patterns showed that peak frequency for Lean animals was more than twice that for Fat animals (2.64 versus 1.17 peaks/6 hours, p<0.001). There was no difference in the peak amplitude. In line with their higher GH concentrations, Lean animals had significantly heavier pituitaries than Fat animals (0.74 versus 0.52 g, p<0.001). Selection for leanness in Coopworth sheep has altered the GH secretory pattern of the animals. The pituitary weight may explain some of these changes in GH secretion.

Hormone secretion patterns associated with increased ovulation rates or with ovarian dysfunction in Inverdale (FecX) ewes - McLeod BJ; Kyle SE; Ramsay MR; Manley TR (Proceedings of the New Zealand Society of Animal Production, 1995)
Ewes that are heterozygous (I+) carriers of the Inverdale gene (FecX) have increased ovulation rate, whereas ewes that are homozygous (II) for the gene are infertile and have 'streak' ovaries in which normal follicle development does not occur. A proportion of ewes with streak ovaries develop structures that have some characteristics of ovarian tumours. We have monitored the growth of ovarian structures and (c) assess the effectiveness of using hormone concentrations to identify the genotype of individual ewe lambs. No differences in hormone secretion related to differences in ovulation rate were evident between I+ and non-carrier (++) Inverdale ewes (mean ovulation rates 3.1+/-0.22 ng/ml) nor inhibin concentrations of gonadotrophins were consistently elevated (FSH 16.9+/-1.8 ng/ml; LH 4.5+/-0.5 ng/ml; N+14) and were comparable to those observed in ovariectomised ewes. In contrast, inhibin was always undetectable (<3.0I.U./ml). These patterns of hormone secretion often change markedly when ovarian structures develop, with inhibin concentrations increasing acutely, which in turn causes FSH levels to fall. To assess the potential of using these differences to identify II genotype, Inverdale ewe lambs were blood-sampled at two, five or seven months of age. Over 95% of II Inverdale ewe lambs had genotype assigned correctly (confirmed by laparoscopy) on the basis of plasma FSH concentrations alone.

Impact of breeding technologies on the genetic gain of Merino flock - Sherlock RG; Garrick DJ (Proceedings of the New Zealand Society of Animal Production, 1995)
Several breeding technologies are available to sheep breeders for increasing the rate of genetic progress in their flocks. The relative merits of these technologies depends on the selection objective and other breeding and management circumstances. This paper investigates the effects of artificial insemination (AI), progeny testing and an open-nucleus flock, on a breeding programme for fine woolled merinos. The selection objective was to decrease Mean Fibre Diameter (MFD) while maintaining Clean Fleeceweight (CFW). Two population structures were considered: a)Maintaining a closed nucleus flock of 1000 breeding ewes b)Operating an open-nucleus breeding scheme sourcing a proportion of replacements from the progeny of 5000 contributing ewes. For each structure, the benefits of AI and progeny testing were investigated individually and in combination. For the range of options considered, selection resulted in a reduction of one micron in MFD every three to five years, with no reduction in CFW. All other things equal progeny testing decreased the genetic progress possible by 0.04-0.06 u/year. An open-nucleus breeding scheme increased the rate of genetic gain by 0.06 u/year with progeny testing or 0.03 u/year in the absence of progeny testing. AI increased genetic progress by 0.06 u/year. The combination of AI and an open nucleus provided the maximum potential rate of genetic gain (0.36 u/year). To optimise the age structure for this combination of breeding technologies, the nucleus flock comprised 60% two-tooth ewes. These results describe the impact of breeding technologies on the rate of genetic gain. To determine their cost-effectiveness, the marginal genetic gain provided by any individual technology must be weighed up against the costs and management constraints that the technology imposes.

Importing a sheep which offers more - the East Friesian - Allison AJ (Proceedings of the New Zealand Society of Animal Production, 1995)
The development of more productive sheep is possible through selection within breeds and crossbreeding or by importing new genetic material. The introduction of new breeds involves complex and time consuming development of import protocols, and health testing of source flocks and individuals prior to entry into NZ. Repeat health testing of sheep (and/or recipient ewes receiving embryos) and long scrapie surveillance protocols are required prior to release. Of the new breeds, the East Friesian with large body size, high fecundity and milk production, leanness and moderate wool production will likely prove the catalyst for a sheep milking industry, and will be a component of a productive meat and wool dam. Early data confirm that the East Friesian offers considerable opportunities in these areas.

Induction of early post-calving ovulation and oestrus in suckled beef cows - McMillan WH; Hall DRH; Oakley AP (Proceedings of the New Zealand Society of Animal Production, 1995)
The aim of this study was to compare the efficacy of exogenous progesterone, either without or with a single injection of gonadotrophin releasing hormone (GnRH), at initiating early post-calving ovulatory and oestrous activity. Six days (d)after the first post-partum follicle had attained dominance cows were allocated to either an untreated control group; treated with a progesterone-impregnated CIDR

Industry use of the Inverdale gene (FecX) - McEwan JC; Davis GH; Fennessy PF; Dodds KG (Proceedings of the New Zealand Society of Animal Production, 1995)
The Inverdale gene (FecX) offers the sheep industry the potential to markedly increase production at little cost. However, the characteristics of the gene mean that appropriate breeding structures are essential. The recommended structure is a stratified crossbreeding system. The three tier breeding structure consists of: (1) a ram breeder producing rams known to carry the Inverdale gene; (2) a ewe breeder producing carrier ewes by mating carrier rams across dual purpose breed ewes; and (3) a lamb producer who mates a meat breed ram with carrier ewes to produce lambs for slaughter. Some farmers may choose to have two, or all three tiers on a single property. If the gene was used to maximum extent possible in Romney and Romney derived breeds, some 40% of all breeding ewes would contain a single copy of the gene and these would produce 31% more lambs for sale per ewe mated. Conservative estimates of the benefits to the New Zealand farmer are approximately $29m per annum.

Influence of milking frequency and feeding level on plasmin activity and casein degradation in milk - Prosser CG; Nicholas G; Stelwagen K; Lacy-Hulbert SJ; Woolford MW; McFadden TB (Proceedings of the New Zealand Society of Animal Production, 1995)
Wool samples from 28 Merino wethers, 31 Corriedale ewes, 37 Perendale ewes and 30 Coopworth ewes were examined for propensity to develop yellow discolouration in relation to the mean fibre diameter and its variability. The propensity of wool to develop yellow discolourations was estimated by two techniques, namely, an incubation technique which measures the colour developed in the wool fibre during an incubation in the laboratory, and the predictive technique described by Aitken et al., 1994. Correlations between propensity to yellow (Y-Z) and mean fibre diameter were low in the Corriedale, Perendale and Coopworth samples, but high in the Merinos. Correlations between propensity to yellow and standard deviation of fibre diameter were also low in the Corriedales, Perendales and Coopworths, but moderate in the Merinos. The correlations between Y and Z and the fibre diameter statistics following similar trends to those for Y-Z. All correlations between propensity to yellow and coefficient of variation of fibre diameter were low. Thus while the propensity to discolour during growth is positively related to fibre diameter in fine wool, no such relationship exists in medium and coarser wool. This provides a further reason for Merino breeders to produce a fine fleece type.

Influence of once daily milking and restricted feeding on milk characteristics in late lactation - Lacy-Hulbert SJ; Woolford MW; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1995)
Ninety 1991 drop Merino wethers, thirty from each of fine, medium and strong wool strains were randomly allocated on the basis of stratified live weight within strains to one of three treatment groups. The first treatment involved grazing ample good quality natural or irrigated pasture (H) throughout the experiment so that the sheep remained in good to excellent condition throughout. The second involved grazing restricted amounts of pool quality nature pasture (L) throughout the experiment so that the sheep remained in backward store condition. As a control, a third group (C) grazed natural pasture such that the sheep subject to seasonal variations in pasture quality and quantity and their condition varied from store to forward store throughout the experiment. Intake was estimated on two occasions; in February 1994, and July 1994, by dosing with controlled-release alkane capsules. Pasture samples were taken at these times based on observation of sheep grazing patterns. However, later analysis showed that the pattern of alkanes in the collected herbage was different to the alkane pattern in faecal samples, indicating that the herbage samples were not truly representative of the herbage consumed by the sheep, particularly at the summer sampling. Actual intake (AI) (expressed as kgOM/day

Inter-muscle variation in the calpain system of red deer:- implications for meat tenderness - Dobbie PM; Singh KK; Thomson BC; Mercer GK; Bass JJ; Speck PA (Proceedings of the New Zealand Society of Animal Production, 1995)
A grazing trial using 24 Red and 24 Hybrid (0.75 Red; 0.25 Elk) deer weaners was conducted from 1st March to 12th December 1993, to compare the feeding value of chicory (Cichorium intybus L) with that of perennial ryegrass (Lollium perenne)/white clover (Trifolium repens) pasture for increasing venison production by one year of age. The deer were rotationally grazed using dry matter allowances of 6, 6 and 7 kg DM/head/day in autumn, winter and spring respectively. Relative to deer grazing pasture, deer grazing chicory had higher voluntary feed intake (VFI), slightly lower grazing (ie. eating) time and substantially lower ruminating time. Hybrid deer had faster liveweight gain (LWG) than Red deer and were heavier at the end of all seasons (P<0.01). LWG was greater on chicory than on perennial ryegrass/white clover pasture during autumn (P<0.01) and there were forage x genotype interactions for liveweight at the end of autumn and spring, with Hybrid deer (especially stags) being heavier when grazed on chicory. Carcass weight for Red and Hybrid stags was 64.9 and 73.0 kg when grazed on chicory and 56.6 and 57.0 kg when grazed on perennial ryegrass/white clover pasture. Grazing chicory advanced the date of first cut velvet antler by 28 days and increased the weight of total (first cut+regrowth) velvet antler. It is concluded that grazing chicory increased venison production, especially in Hybrid stags with increased growth potential, and increased velvet antler production.

Inverdale as a model - Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1995)
The Inverdale gene (FecX) is extraordinary. Located on the X- chromosome, it increases ovulation rate in the heterozygous state, but in the homozygote the ewe has undeveloped or "streak" gonads and is sterile. The phenotype is almost certainly due to the action of the gene in early embryonic/foetal development. The Inverdale may be valuable model for investigation of similar phenotypes in other species, especially the human female. Identification of the gene itself will enable substantial progress in understanding mechanisms of ovarian and follicle development. However, even without knowledge of the specific gene function, there are the areas where the phenotype itself may be of real value. Two such areas are the "tumour-like" structures in the homozygote as a model for ovarian tumours and the "steroid-free" environment of the homozygote as a model for investigating the regulation of seasonality in sheep.

The Inverdale prolicacy gene: contract summary - Duffy RG (Proceedings of the New Zealand Society of Animal Production, 1995)
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The Inverdale prolificacy gene in sheep - Davis GH (Proceedings of the New Zealand Society of Animal Production, 1995)
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Living with the Inverdale gene (FecX) in a Romney flock - Hanna MM (Proceedings of the New Zealand Society of Animal Production, 1995)
This paper discusses a Romney flock where the Inverdale gene was identified in 1993, but it almost certainly traces back to a 1968-born ewe that had triplets in four successive lambings. It appears that the first Inverdale ram used in the flock was a triplet son of this ewe, born in 1970, because several ewes born in 1972 produced triplets or quadruplets. The breeding programme has been based on all ewes being given the same treatment, and thus multiple rearing ewes had to perform well if their progeny were to be selected. Carrier ewes have the range of qualities present in the larger population and the same management practices, production objectives and procedures can be applied to them as to non- carrier sheep. The only difference is the enhanced prolificacy and the management requirements that may impose. Records show that they maintain condition well and have a long life expectancy.

Maternal antibodies and immune responsiveness in growing lambs - McQuoid MR; Hodgkinson AJ; Hodgkinson SC (Proceedings of the New Zealand Society of Animal Production, 1995)

Metabolic changes of cadmium and zinc in kidney and liver tissue during foetal development in Romney and Merino sheep - Rounce JR; Lee J; Treloar BP; Grace ND; Sinclair BR (Proceedings of the New Zealand Society of Animal Production, 1995)
Diseases affecting mucosal surfaces, especially gastrointestinal disorders, cause high mortality rates in young domestic livestock. Hyperimmune milk products, using milk secretions from ruminants immunised systemically with enteric pathogens, have been shown to confer passive immunity against such disorders but the results are variable. To study the type and titre of immunoglobulin (Ig) classes produced in milk secretions after immunisation with gut pathogens, we have developed ELISAs for the estimation of ovine IgG and IgA antibodies directed against E. coli. Utilising an indirect ELISAs technique, the method involved coating antigen onto microtitre plates then sequential addition of test sample dilutions (containing primary antibody), anti-class-specific antibody and anti- species horse radish peroxidase labelled antibody. Colorimetric end point detection employed 3, 3

Mitogenic activity of lamb mammary fat pad in vitro is distinct from that of mouse mammary fat pad - Hovey RC; McFadden TB; MacKenzie DDS (Proceedings of the New Zealand Society of Animal Production, 1995)
Apple pomace, a by-product of the apple juicing industry, was assessed as a supplementary feed for lactating dairy cows during autumn. Cows were offered a base diet of 6 kg DM/cow/day from grazed pasture and one of three supplement treatments; control (7 kg DM/cow/day grass silage); apple pomace (AP) (3 kg DM/cow/day grass silage plus 4 kg DM/cow/day fresh AP); and AP+"balancer" (3 kg DM/cow/day grass silage plus 3 kg DM/cow/day fresh AP plus 1 kg DM of by-pass protein meal supplement ("balancer"). Treatment groups each comprised 10 mixed age Friesian-Jersey crossbred cows which were fed the supplement(s) in their respective groups in two equal portions following morning and evening milkings. Groups were grazed independently on similar pastures between these times. Herd test milk yields over the 28 day supplementary feeding period were greater for the AP and AP+"balancer" groups (14.1 & 14.7 litres/cow/day, respectively) than for the control group (12.1 litres/cow/day; P<0.001). Milk protein yields were lower for the control than the two AP groups (0.43 vs 0.54 & 0.57 kg/cow/day for control, AP and AP+"balancer", respectively; P<0.01). Yields of milkfat (0.58 vs 0.70 vs 0.77 kg/cow/day) and milksolids (1.01 vs 1.24 vs 1.34 kg/cow/day) differed between all three treatment groups (P<0.05). Cow condition and bodyweights were similar between the three treatment groups at both the start and end of the trial. Apple pomace was therefore shown to be a useful supplement for dairy cows in late lactation.

MOET in ultrafine Merinos: An experimental evaluation - Wuliji T; Aspinall J; Land JTJ; Shackell GH; Dodds KG; Andrews RN; Rogers J (Proceedings of the New Zealand Society of Animal Production, 1995)
Results of experimental MOET programme in elite ewes selected from within an ultrafine Merino flock are presented. Of the treated ewes, 60% provided transferable donors with a mean of 16.7 ovulations and 10.4 embryos recovered, 7.8 embryos transferred, 3.9 lambs born and 3.1 lambs weaned per donor ewe. The wool produced by hoggets from this elite embryo transfer group was 0.9 um (P0.01) finer than that from their contemporaries in the ultrafine selection flock and 2.5 um (P0.01) finer than a random Merino control group. The improvement in fibre diameter was better than expected from the selection differentials, but not significantly so. The h2 estimates for liveweight, clean fleece weight, fibre diameter and yield in three flocks of fine woolled Merinos were 0.50, 0.32, 0.39 and 0.58 respectively. The MOET programme was successfully applied to increase the number of progeny from elite ultrafine Merino ewes.

Monitoring wool fibre diameter and length changes using gel emulsion autoradiography - Friend MA; Robards GE (Proceedings of the New Zealand Society of Animal Production, 1995)
The ability of New Zealand cows to achieve high milksolids production has been well documented, but less than 1% of New Zealand dairy herds consistently achieve more than 350 kgs milksolids (MS) per cow per season. A survey was undertaken to characterise seasonal dairy farms in the lower North Island that had achieved an average production of at least 348 kg MS per cow over three seasons (n=31 farms from 1162 suppliers). Thirty of these farmers were interviewed. The farmers averaged 51 +/- 11 years of age and had 31 +/- 10 years of dairy farming experience. The average herd size of 164 (range 52-515) cows was milked on 66.5 hectares (2.48 cows/ha). Milksolids production of 386 +/- 28 kg per cow was achieved from an average lactation length of 274 +/- 10 days. Peak MS production ranged from 1.16 to 2.09 kg/day. Production equated to 881 kg MS/ha and 56,800 kg MS/farm. Friesian and Friesian x Jersey cross cows predominated (87% of herds). Hay, silage, nitrogen, and grazing young stock off the milking area were used to increase the feed available to the milking herd. In pasture equivalent terms this equated to 315 kg DM/cow as hay, 342 kg DM/cow as silage and 198 kg DM/cow from nitrogen-boosted pasture. Concentrates and summer crops were each used by nine farmers to provide additional feed to their herds. There was a significant correlation between total feed inputs and days in milk )r+0.49, P<0.01). Per cow production was associated with soil fertility (r=0.48, P<0.01), and peak milk production (r=0.68, P<0.001). A wide range of management systems were used to achieve high per cow production, but a common aim was to feed cows as well as possible.

Mount Linton wools - now and beyond 2000 - McGregor A (Proceedings of the New Zealand Society of Animal Production, 1995)
At Mount Linton Station the emphasis in wool production is moving away from the concept of quantity alone, towards a philosophy of quantity and quality. The quality component is being driven by end-user requirements. With this in mind we are working closely with a specific company, Summit Wool Spinners in Oamaru. We are also investigating the possibilities for producing specialty crossbred wools, examples of which include the creation of "branded" lines produced under an appellation standard and "chemical-free" wool. The demands of the manufacturer are having an increasing impact on the genetics and ram breeding elements of Mount Linton's wool production system. The change of emphasis towards quality wool production and the genetic requirements for parasite resistance resulting from reduced pesticide use, will put increasing pressure on our ram-breeding enterprises. By capitalising on the large numbers of animals we have available we can meet the challenge of concentrating on producing high quality wool products for specialist markets. To achieve this, the linkage between the farm and the end-user is vital to the future of Mount Linton Wools.

Near-infrared reflectance analysis of intramuscular fat in beef - Smith DR; Smith NB; Muir PD (Proceedings of the New Zealand Society of Animal Production, 1995)
In adult sheep, cadmium (Cd) accumulates in both liver and kidney tissue in an age dependent manner. To quantify the accumulation of Cd in the developing foetus and investigate the relationship with the Cd status of the maternal parent, liver and kidney samples were collected from both Romney and Merino foetuses, approximately fortnightly, from 60 days after conception up to parturition, and from the suckling lamb, weekly over three weeks. Matching liver and kidney samples were also obtained from the dam. Tissue sub-samples were analysed for metallothionein-mRNA by dot blot hybridisation of total RNA extracts to assist in identifying regulatory aspects of Cd accumulation in hepatic foetal tissue and any relationship with Zn. Cadmium concentrations (means

New sheep: a catalyst for change - Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1995)
Since the completion of the latest GATT negotiations a lot of reflection has been devoted to new opportunities that will be offered to New Zealand's primary industries, but there is a more subtle issue that is less frequently mentioned. The effects of competition will be felt by every sector of every industry. In a country committed to freer trade and in a world increasingly moving in the same direction, no industry will be able to lay claim to more land, water, research resources or investment than it can justify by way of return. For the sheep industry, this means looking beyond mere survival, towards shaping the future by making the best possible use of resources devoted to it. Sheep farming must become more than just a default land use.

New sheep - a catalyst for change - Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1995)
New sheep may be alternative breeds brought in from other environments, new synthetic breeds developed by crossbreeding or as specific crossbred combinations, or new strains of existing breeding populations developed by selection for production traits, identifiable genes or gene complexes. Changing gene frequency is the main underlying feature of all these approaches to genetic improvement. Selection of parents is the common operational ingredient. New products have been a major factor in changing the breed structure of our sheep industry. New more productive breeds have also been produced utilising the complementary features of existing breeds, but with little widespread development of crossbreeding systems based on first cross ewes. Improved reproductive rate from selection or use of new fecund genotypes offers much scope for specialised production of quality market lambs, especially when stratified production a major stimulus to the improvement of terminal sire breeds. They are re-focusing the balance of emphasis on lamb growth and carcass and encourage a search for unique genetic effects on meat quality traits.

Nitric oxide and the control of mammary blood flow - Lacasse P; Farr VC; Davis SR; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 1995)
This study monitored the behaviour of calves docked with a rubber ring with or without local anaesthesia. Forty five 3 to 4 month old Friesian heifer calves were divided equally into three groups viz control (C), docked following local anaesthetic (L). After treatment the calves were returned to a paddock where their behaviour was monitored continuously for 5 hours with scan sampling every 10 minutes. Standing, walking, grazing and ruminating behaviours were similar in the 3 groups. Within 30 minutes of the treatment tail shaking, and vocalization occurred in 10 and 5 R calves and of them 2 calves continued to tail shake and vocalise for a further 60 minutes. Tail shaking and vocalisation occurred in 7 and 5 of the L calves respectively at 150 minutes. Two of these calves vocalised at 180 minutes and one at 210 minutes following treatment. C calves did not shake their tails or vocalise. These observations suggest that milk distress was experienced by approximately two thirds of docked calves.

Nutritive value of chicory (Cichorium intybus L) for venison production - Kusmartono; Barry TN; Wilson PR; Kemp PD; Stafford KJ (Proceedings of the New Zealand Society of Animal Production, 1995)
Results from farmlet studies indicated that anthelmintic treatment of ewes during pregnancy virtually eliminated ewe parasite faecal egg counts and lead to significantly higher lamb weaning weights. The objective of this study was to develop strategies to enable the rearing of lambs within minimal anthelmintic administration. There were four farmlets, with paired units on dry and irrigated land (5 and 6.4 ha respectively) with mixed aged flocks of 60 or 80 ewes respectively. One flock on each pair of farmlets, termed treated flock, were treated with a continuous anthelmintic release bolus in March prior to mating and again 100 days later in June. The control flock of each pair was given an oral anthelmintic post-lambing in line with local farmer practice. In March of both years faecal egg counts (FEC) were similar for all flocks and averaged between 40 and 160 eggs per gram (peg). For bolus treated flocks average FEC declined to 0 after treatment and remained below 32 peg until September. In contrast the control flocks had significantly higher (P<0.001) egg counts at levels of 50 to 600 epg throughout winter, but exhibited the classic periparturient peak in 1993 only. From October all flocks had similar FEC

Ovarian characteristics in Inverdale ewes heterozygous (I+) and homozygous (II) for the Inverdale gene (FecX) - McNatty KP; Smith P; Hudson NL; Lun S; Heath D; Shackell G; Corrigan K (Proceedings of the New Zealand Society of Animal Production, 1995)
The Inverdale gene (FecX) affects ovarian development, during both foetal and adult life. There is evidence for affects on germ-cells, the follicle and the corpus luteum. In I+ewes, follicles ovulate at a small diameter with fewer granulosa cells and the resulting corpora lutea are individually smaller compared to those in control (++) animals. This appears to be due to the granulosa cells in I+ follicles being more responsive to follicle-stimulating hormone (FSH) and acquiring receptors for luteinising hormone (LH) earlier than in cells from ++ ewes. These differences between I+ and ++ ewes in ovarian characteristics occur in the absence of any obvious differences in the peripheral plasma concentrations of FSH and LH or the ovarian secretion rates of inhibin, oestradiol and progesterone. In II animals, ovarian follicular growth is impaired at the primary stage of growth during foetal, neonatal and adult life. No normal follicles beyond this stage of growth have been observed. II animals also have castrate levels of FSH and LH and undetectable plasma levels of ovarian steroid or inhibin. In ~35% of II animals, abnormal surface-visible structures have been observed with a morphology consistent with that of a sertoli-cell or sex-chord stromal tumour. These structures, which secrete inhibin, appear to develop from clusters of oocyte-free follicles.

Partitioning of milk accumulation between cisternal and alveolar compartments of the bovine udder: relationship to production loss on once-daily milking - Farr VC; Davis SR; Copeman PJA; Carruthers VR; Knight CH (Proceedings of the New Zealand Society of Animal Production, 1995)
Colour is an important characteristic affecting wool price. Canary yellow wool incidence is low in dry years but individuals can be classified according to their degreee of susceptibility to wool yellowing based on results of wool incubation test. Australian Merino, Corriedale and New Zealand Romney populations were tested. A number of 603, 1269 and 476 progenies and 21, 52 and 24 sires were used for these populations, respectively. Susceptibility to wool yellowing (YPC), greasy (GFW) and clean fleece weights (CFW), yield (Y) and mean fibre diameter (MFD) were analysed in a sire model. Heritability values for YPC were 0.21+/-0.11, 0.28+/-0.08 and 0.19+/- 0.07 for Merino, Corriedale and Romney, respectively. Genetic correlations between YPC and other traits were 0.04+/-0.31 with GFW, - 0.10+/-0.31 with CFW, -0.11+/-0.29 with Y and 0.51+/-0.29 with MFD for Merinos; 0.30+/-0.18, 0.17+/-0.19, -0.12+/-0.18 and 0.33+/-0.19, - 0.12+/-0.18 and 0.33+/-0.19 for Corriedale, respectively, and 0.77+/- 0.22, 0.44+/-0.31, -0.70+/-0.35 and 0.25+/-0.30 for Romney, respectively. Phenotypic correlations were negligible among this traits for these three populations, except for YPC and Y (-0.33+/-0.10). Selection strategies to reduce wool yellowing susceptibility will differ between genotypes. Low frequency of susceptible sheep in Merino population showed little justification for including YPC in genetic programmes for this particular breed only.

Plasma cholesterol and triglyceride concentrations in yearling Angus cattle - Morris CA; Cullen NG; Upreti GC (Proceedings of the New Zealand Society of Animal Production, 1995)
The Stockpol model was designed for decision support on New Zealand sheep and beef cattle farms. It indicates the biological feasibility of a livestock system and provides the opportunity for users to test alternative livestock policies. An evaluation of the Stockpol model was made using 44 data sets from farmlet trials at Gore, Ballantrae, and Whatawhata Research Centres and data from Massey University's Riverside farmin the Waiarapa. These data covered a range of sheep and beef finishing systems. The main test compared the measured pasture growth rate with that required by Stockpol to predict the monthly pasture cover recorded in the data. Measured and required pasture growth rates differed significantly (<0.01) in July, August and September. The model was conservative and required an average of 5.1 kgDM/ha/day more growth over these months than was measured. In other months the differences were small and non significant. When animal demand was adjusted to mimic pasture cover, adjustments of minus 22% from July to September were required. Overall it was considered tha Stockpol can be used with confidence for analysing options for farmer decision making. Areas for further improvement of Stockpol have been defined as the pasture growth model in early spring. Aspects of the animal demand in early spring also need to be tested more vigorously. The evaluation emphasised the importance of consistent input data for use in models. For example, the pasture measurement technique was different at each of the four sites studied. This may explain some of the variation between predicted and measured data.

Presidential address: some advantages of corporate animal production - Nicoll GB (Proceedings of the New Zealand Society of Animal Production, 1995)
Staple tenacity is an estimate of the peak force to break a staple of a certain cross-sectional area at the point of break. Staple strength is a measure of peak force to break a certain weight of staple. Using the density of wool and the length of staple broken, both estimates can be converted to force per unit linear density (N/ktex). The relationship between these two estimates was examined. Midside wool samples were collected at shearing from 164 ewe hoggets from lines of New Zealand Romneys that have been selected for or against staple tenacity, and a randomly selected control line. Five staples from each sample were measured for staple strength and staple tenacity. This was accomplished by defining the cross-sectional area at the break point, breaking the staple to estimate peak force and then cutting the portion of the staple from between the jaws and determining the weight of clean wool after scouring. The High staple tenacity line had a significantly higher staple strength (P<0.001) and staple tenacity (P<0.001). Although a similar weight of greasy wool was removed from between the jaws for each selection line (P=0.336), the weight of clean wool was significantly greater in the High staple tenacity line (P=0.003). Covariate analysis revealed that the fitted relationships between staple strength and staple tenacity for the three selection lines had similar slopes (P=0.822) but significantly different intercepts (P=0.029). Staple strength is thus biased relative to staple tenacity in these lines, because of the differences in weight of wool between the jaws, for staples which are all the same cross-sectional area at the point of break. Staple tenacity is therefore more useful for some purposes than staple strength and vice versa, and care should be taken when drawing comparisons and conclusions and when considering which to use.

Quantitative indicators of stress in stress-susceptible and stress- resistant breeds of pigs - Spencer GSG (Proceedings of the New Zealand Society of Animal Production, 1995)

Regulation of lactose production by ovine mammary acini in culture - McFadden TB; Callaghan MR; Davis SR (Proceedings of the New Zealand Society of Animal Production, 1995)
Five sets of rising five year old Holstein-Friesian non-lactating identical twin cows were studied from February to April 1994. One member from each twin pair had been tail docked at 18 months of age while the other member had its tail intact. The animals were observed weekly at three different times of day; 7am, 12 noon and 3pm. At low fly levels there were no significant differences in the frequencies of either front (eg. leg stamping) or rear (eg. tail flicking) focused fly- induced behaviours between the two treatments. At high fly levels there were no significant differences in front focused behaviours but the docked animals performed significantly more rear focused behaviours than the non-docked cows (eg. 96 vs 34 tailflicks at 12 noon, p<0.05). The adrenocorticol responses to intravenous injection of 0.05mg ACTH (Synachthen, CIBA-GEIGY) or saline was assessed four times throughout the experiment. The animals were blood sampled at time - 1min, 50 and 120 min relative to the time of injection of ACTH or saline. There were no significant differences in plasma cortisol concentrations in response to ACTH injection between treatments. Tail docked cows had elevated levels of fly induced behaviour but did not have an altered adrenal cortex function. This suggests that behaviour is a more sensitive indicator of the effects of fly predation than adrenal response to ACTH. Sensitive physiological indicators of chronic stress need to be developed for the assessment of husbandry practices.

Relationship between bioimpedance and muscle mass in chilled lamb carcasses - Hopkins DL; Hegarty RS (Proceedings of the New Zealand Society of Animal Production, 1995)
East-Mediterranean natural pastures are characterised by extreme seasonal variation in nutritional value. High quality green standing pasture is available only during the rainy season (Dec-May), whereas during the rest of the year the standing pasture is dry and of low quality. The main objective of this study was to investigate the potential of increasing weaning rates and weaning weights on a commercial beef suckler herd under the above conditions. The main 3 means to achieve this were: (I) increasing stocking rate, (ii) intensive trough-feeding, during the dry pasture season, of rations based on recycled wastes, and (iii) short calving periods. Main input-output data in the 1st and 10th year of the study, respectively, were as follows: herd size: 424, 624 cows; stocking rate 0.19, 0.29 cow/ha of pasture; trough-fed ration; 1, 2 metric tons DM/cow/year; energy in trough- fed ration: 7.5, 8.8-9.6 MJ ME/kg DM; percent cows calving in the first 2 months of the calving season (Aug. + Sept.): 35, 89; percent cows weaning (of exposed to mating bulls): 73, 86; avg. calf weaning weight 206, 259 kg LW; total weaned calf crop: 64, 138 metric ton LW/year. These data present a potential model for improving the efficiency and increasing the volume of range beef production under Mediterranean-type pasture conditions. Studies are in progress on intensive beef production (I) by suckler herds in full confinement - fed year-round on rations composed mainly of recycled wastes, (ii) by dual-purpose cattle - in dairy herds under milk quotas, and (iii) under desert conditions based on grazing or trough-feeding forage irrigated with saline water and/or purified recycled sewage water.

The relationship between cortical structure and fibre diameter in primary and secondary wool fibres of yearling Perendale sheep - Dick JL; Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1995)
The effects on bloat of herbage mass and of removing Poa from pasture was investigated. Twelve paddocks were paired on pasture composition in autumn and Poa seedlings were removed from one paddock in each pair. Each paddock was halved and two levels of herbage mass were established. The resulting treatments, high herbage mass with Poa (H+P), high mass without Poa (H-P), low mass with Poa (L+P), and low mass without Poa (L-P), were grazed by four groups of six cows of high susceptibility to bloat over four 12-day periods in spring. Herbage mass was 814 kg DM higher (P<0.001) before grazing and 518 kg DM/ha higher (P<0.001) after grazing on H versus L.Poa content (% DM) was higher and white clover in +P compared to -P (Poa 11 and 2%, P<0.001; clover 16 and 26%, P<0.001). The average bloat score was highest on L-P and least on H+P and was 2.4 times greater on L than H and 5.5 times greater on -P than +P. Results indicated that bloat could be manipulated by altering herbage mass, but any effect on bloat of Poa was confounded with changes in white clover content.

The relationship between daily Se intakes and blood Se concentrations in pregnant dairy cows - Grace ND; Mills AR; Death AF (Proceedings of the New Zealand Society of Animal Production, 1995)
In ruminants protection against environmental pathogens in the early post-natal period is largely dependent on passively-acquired immunity from maternal colostrum since evidence suggests placental transfer of antibody does not occur. Our overall aim is to develop antibody based treatments for protection of neonatal animals. In this study we have re-examined aspects of maternal antibody transfer to offspring especially in the light of recent evidence that feeding specific antibodies to neonatal rats decreases subsequent immune responses to the corresponding antigen. In experiment 1, pregnant ewes immunised with model antigen (human growth hormone) were terminated at 135 days gestation and blood samples collected from the ewe and fetus. Analysis of fetal plasma by antibody dilution/tracer binding assay procedures produced no evidence of antibody transfer to the fetal circulation via the placenta. In a further study the kinetics of specific antibodies were examined in lambs from immunised ewes. One group of lambs was permitted to suckle from the ewe for the duration of the trial (40 days) whereas the other group was permitted initial sucklings only, separated from the ewe 24 hours post partum and then fed a milk substitute. Analysis of specific antibodies titres revealed a very similar trend in both the amount of antibody transferred to lamb plasma and its persistence with the half-life for both groups calculated at approx. 13 days In the second experiment lambs from ewes immunised during pregnancy against E.coli and fed specific antibodies via maternal colostrum as neonates were compared to a matched control group of lambs derived from non-immunised ewes for subsequent immune responses against the same antigen. Peak antibody titres as analysed by ELISA were lower in lambs from immunised ewes than in control group lambs (mean titre (-log 10) 5.29

Relationship between wool colour and fibre diameter in four breeds of sheep - Reid TC; Botica KJ (Proceedings of the New Zealand Society of Animal Production, 1995)
The influence of season on the composition of milk from approximately 200 Beta-lactoglobulin (B-LG) AA and 200 B-lactoglobulin BB phenotype cows was determined for the 1992/93 and 1993/94 seasons. Marked seasonal fluctuations were observed in all components measured: protein, casein, whey protein, ash, lactose, alpha-lactalbumin, B-LG, alpha/s- casein, Beta-casein, k-casein (k-CN), bovine serum albumin, calcium, magnesium, sodium, potassium, chloride, and phosphate. Significant differences in composition were observed between the AA and BB phenotype milks, with the Beta-LG BB phenotype milk containing more total protein, casein, fat, and total solids, whereas the Beta-LG AA phenotype milk contained more whey protein, Beta-LG, and had a higher ratio of Beta- LG to k-CN. Such differences in composition could have a marked effect on the physicochemical characteristics of these milks. The higher concentration of casein found in the Betal-lactogloblin BB type milk should make this milk type more suitable for the manufacture of cheese and casein.

The relationship between wool production, live weight and liveweight change in four specialty carpet wool breeds, Romneys and Merinos - Champion SC; Robards GE (Proceedings of the New Zealand Society of Animal Production, 1995)
Changes in plasma concentrations of cortisol, ACTH and free fatty acids were evaluated as quantitative indicators of stress in pigs of stress- susceptible and stress-resistant breeds. The changes in these concentrations following loading, transport and subsequent resting in lairage were examined. Resting concentrations of cortisol were higher (P<0.01) in stress- susceptible Pietrain pigs (44.0

The relative intake of three Merino strains under different grazing regimes estimated using alkane technology - Friend MA; Robards GE; Lindsay AR; Champion SC (Proceedings of the New Zealand Society of Animal Production, 1995)
As part of a study measuring the effect of a variant of insulin-like growth factor-1 (long-arg3-IGF-1; LR3IGF) on tissue amino acid utilisation in sheep, changes in plasma Cu, Fe and Zn concentrations were observed. LR3IGF-1 was infused continuously over 21 days into the skin of 6 sheep using a bilateral arterio-venous preparation. Another 6 sheep were infused in the same way with saline only (controls). Feed intakes were the same for both groups. Arterial blood samples were obtained prior to the start of treatment and at 1, 7, 14 and 21 days. Plasma samples were prepared and analysed for concentrations of endogenous IGF-1, insulin, cerulophasmin, macro-elements (Ca, Mg, Na, P and S) and the trace elements, Cu, Fe, Mn and Zn. Plasma concentrations of the macro-elements were unchanged over the treatment period and were not significantly different between the two groups. However there was a significant effect of treatment (P<0.001) and treatment x time interaction (P=0.024) on the Cu concentration in plasma. After 7 days the Cu concentration in plasma of the LR3IGF-1 group increased from 1.06

Reproductive performance of synchronised lactating dairy cows - Xu ZZ; Burton JR; Burton LJ; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1995)
The objective of this trial was to evaluate the reproductive performance of lactating dairy cows following oestrous synchronisation with a combination of progesterone, oestradiol and prostaglandin. Cycling cows in 11 herds were randomly divided, with restriction to age, calving date, condition score and breed, into synchronised (n=1332) groups. Those in the synchronised group were each treated with an EAZI-BREED

Response of trace element concentrations in plasma of sheep to chronic infusion of a recombinant variant of IGF-1 - Lee J; Rounce JR; Hocking-Edwards JE; Harris PM (Proceedings of the New Zealand Society of Animal Production, 1995)
Bio-ijmpedance (BI) is the opposition of biological tissues to the flow of an alternating low electrical current. Tissue BI is quantitatively inversely related with tissue hydrational status. Several reproductive events of importance in the management of the cow are characterised by changes in fluid content and electrolyte concentration of the genital tissues; these changes can be detected and quantified by genital tissue BI monitoring. The objective of this presentation is to review existing and potential applications of monitoring genital tissue BI in cows as aids to cattle reproductive management. The main application is genital BI monitoring to determine the optimal insemination time. It is based on the fact that intravaginal and vulvar tissue BI decline ca 10-30% during the peri-ovulatory stage of the ovarian cycle. Genital BI measurements can also be used to detect pending calving as well as post partum reproductive disorders: vulvar BI, measured with chronically implanted electrodes, declines ca 15 d before, and remains low until calving. During ca 40d post-calving, vulvar BI increases gradually and stabilises at about the time of resumption of ovarian luteal cyclicity. Intravaginal BI during the first 4-6 weeks post-calving is significantly lower in cows with reproductive disorders than in

The role of endogenous insulin-like growth factors-1 and -2 on lactation in rats - Spencer GSG; Hodgkinson SC; Berry CJ (Proceedings of the New Zealand Society of Animal Production, 1995)
Records were obtained for 1617 heifers in 26 herds using the Genermate

Seasonal changes in LH profiles of ewes selected for and against an early lambing date - Smith JF; Briggs RM; Parr J; Johnson DL; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1995)

Seasonal patterns of wool growth in Romney sheep selected for high and low staple tenacity - Woods JL; Bray AR; Rogers GR; Smith MC (Proceedings of the New Zealand Society of Animal Production, 1995)
Twenty Jersey and 12 Friesian cows were individually offered freshly cut pastures that had received either 100-150 kg nitrogen (N)/ha (HN) or 25 kg N/ha (LN) as urea, either ad lib. or restricted to 70% of ad lib. Treatments were imposed for 2 consecutive 14-day periods during September and October 1993. Effects of N fertiliser on the chemical and botanical composition of pasture were minor. There were no significant effects of N fertiliser on mean fat corrected milk yield, (19.9 kg/day 4.0% FCM), milk yield (16.2 kg/day), milk fat % (5.6%), milk fat yield (0.9 kg/day), or liveweight change (-0.59 kg/day). Milk protein yield (P.0.05) and protein % (P<0.05) and protein % (P0.01) were greater for LN than for HN treatment groups (0.58 vs 0.56 kg/cow/day and 3.6 vs 3.5% respectively). Voluntary DMI was also affected by N fertiliser for cows on ad lib. pasture allowance (14.0 vs. 14.6 kg DM/cow/day for HN and LN treatments; P<0.01). The application of N fertiliser in winter/early spring, had only minor effects on pasture intake or milk yield and composition in early lactation.

Selection for beef quality traits - Charteris PL; Garrick DJ; Morris ST; Wright LA (Proceedings of the New Zealand Society of Animal Production, 1995)
Records on 24 146 Angus and 5 632 Hereford carcasses processed at Manawatu Beef Packers between March 1993 and August 1994 which had been evaluated for beef marbling standard (BMS), beef fat standard (BFS) and beef colour standard (BCS) were used to derive overall meat quality score. Overall meat quality score in the Japanese grading system is determined by the lowest grade from: semi-objective assessment for BMS, BFS and BCS; and subjective assessment for meat brightness, firmness and texture, fat lustre and quality. Subjective measures of meat and fat quality are not routinely recorded at this plant and therefore overall meat quality score could only account for the three recorded items. The majority of Angus and Hereford carcasses (84.0 and 82.9%) had an overall meat quality score of 1 (inferior) and no carcasses had score 5 (excellent). This study reports the effects of selection to improve Japanese overall meat quality score by single trait improvement of the three meat quality attributes. A change of one grade in BMS (or BFS) for Angus carcasses decreased the proportion of score 1 carcasses to 12.8% (or 74.7%) and improved overall meat quality score from an average of 1.17 to 1.96 (or 1.29). A change of one grade in BMS (or BFS) for Hereford carcasses decreased the proportion of score 1 carcasses to 16.1% (or 66.8%) and changed overall meat quality score from an average of 1.18 to 1.90 (or 1.35). Selection based on a well-designed progeny test would take 5 (or 9) years to improve BMS (or BFS) by one grade. Biological factors introduce a lag of at least six years from the start of test matings until there can be widespread harvest of beef animals with improved meat quality. Selection for BMS can improve overall meat quality score more effectively and more rapidly than selection for other meat quality traits.

Sensitive PCR for detecting Benzimidazole resistant sub populations of ovine nematodes in the Waikato - Lehrer S; Davey H; Watson T; Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1995)

Sheep farming - beyond survival - Campbell R (Proceedings of the New Zealand Society of Animal Production, 1995)
none supplied

Sires for more valuable lambs - McEwan JC; Davis GH; Fennessy PF; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1995)
Specialist terminal sire breeds offer several advantages to the commercial farmer, particularly their ability for rapid change in relevant traits in response to market signals. The production, survival and disease resistance benefits resulting from the hybrid vigour in the crossbred progeny have also widely documented. Terminal sires breeds also provide for efficient utilisation of between breed differences in carcass quality and mature weight. However, terminal sires are presently under utilised by the NZ sheep industry. In future this situation is expected to change. Long term trends suggest that carcasses will be paid for on the basis of weight of lean meat. In addition, terminal sire breeders are increasingly using performance recording systems allied with methods of estimating carcass composition, both of which have markedly improved in recent years. Terminal sire breeds are the logical method to distribute major genes affecting growth and carcass quality. The identification, characterisation and "packaging" of these genes will become increasingly routine.

Some effects of using progesterone and oestradiol benzoate to stimulate oestrus and ovulation in dairy cows with anovulatory anoestrus - Macmillan KL; Taufa VK; Day AM; McDougall S (Proceedings of the New Zealand Society of Animal Production, 1995)
Anovulatory anoestrus (AA) is a major form of infertility in pasture- fed dairy cows in New Zealand and is most frequently treated by injecting equine chorionic gonadotrophin (eCF) after pre-treatment with progesterone (P4). The effectiveness of this treatment varies between herds. Injecting oestradiol benzoate (ODB) from 24 h to 48 h following PA4 and ODB priming can also induce oestrus and ovulation in AA cows. Two field trials compared responses in 572 cows with AA treated with P4 alone, P4 + eCG and P4 + ODB. The P4 was administered per vaginum for 5 or 7 days using a CIDR device. An injection of 1 mg ODB at 48 h after device removal in Trial 1 increased the insemination submission rate during the following 4 days from 55% among cows treated with P4, or P4 + eCG to 75%, and reduced the incidence of non-responding cows from 21% to 3%. In Trial 2, the comparable results to ODB treatments were 86% inseminated and 3% not responding. The increased submission rates were not due to the ODB producing oestrus without ovulation. Consequently, 42% of anoestrous cows treated with ODB conceived during the first week of AB, 75% conceived after 6 weeks of AB and only 5.5% were finally not pregnant. Comparable figures for herdmates treated with P4 but not injected with ODB were 29%, 66% and 12% respectively. Injecting a low dose of ODB from 24 to 48 h after P4 pre-treatment can be used to successfully treat AA in dairy cows.

Staple tenacity versus staple strength - Scobie DR; Merrick NC; Bray AR (Proceedings of the New Zealand Society of Animal Production, 1995)
Six nutritional regimes were applied to 134 Friesian heifers to determine the effects of differential rearing on productive and reproductive performance. Cycling animals were identified at 11.5 and 15 months by measuring progesterone in consecutive weekly blood plasma samples. Heifers were synchronised using CIDR devices and artificially inseminated for two cycles, followed by six weeks of natural mating. At 11.5 months, 95% of the high (268 kg LW), 65% of the medium (242 kg LW), and 2% of the low (186 kg LW) nutrition groups were cycling. At 15 months, all heifers in the four high groups were cycling compared to only 82% of heifers in the two low groups was probably enhanced by the CIDR progesterone treatment stimulating puberty in non-cycling heifers. Friesian heifers should average 300 kg to ensure all animals are cycling normally prior to the start of mating.

Tail docked dairy cattle: fly induced behaviour and adrenal responsiveness to ACTH - Phipps AM; Matthews LR; Verkerk GA (Proceedings of the New Zealand Society of Animal Production, 1995)
Romney crossbred lambs (n=711) sired by selected Southdown high fat (SD+), low fat (SD-) and Texel rams were grown from weaning to 14 months of age under high(H), medium (M) or low (L) nutrition. A random half of H and L groups were run with the L and H groups respectively from 8 months onwards. Samples of lambs were slaughtered at 3, 5, 8, 11 and 14 months of age. Whereas there were significant carcass weight differences between nutrition and were almost always fatter than the SD- and Texel lambs. All genotypes showed markedly reduced levels of fat development during the post-weaning and winter periods, with highest levels in spring. Eye muscle width was more nutritionally responsive than eye muscle depth and, in relation to carcass weight changes, was greatest in winter.

Ultrasonic scanning of lamb carcasses for non-destructive carcass quality measurements - Binnie DB; Farmer RJ; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1995)
Compensatory growth in cattle has been regularly reviewed (Allden, 1970; O

Using genetic variation for greater profit - Nicoll GB (Proceedings of the New Zealand Society of Animal Production, 1995)
Over 20 years ago, cooperative group breeding schemes screened large gene pools to establish ram breeding flocks. This process invariably exploited differences between animals within a breed and not differences between animals regardless of breed. This paper describes the establishment and operation of Landcorp Farming Limited's Lamb Supreme (LS) terminal sire breeding programme and presents results of a comparative slaughter trial for discussion. In 1989 and 1990 Landcorp screened a total of 3,685 ewe hoggets from 501,000 animals. The progeny from 3 years' mattings of these screened- in ewes constituted the nucleus flock of the LS programme. The progeny of rams from this flock mated to commercial Romney ewes were compared with straightbred Romneys (R) in a slaughter trial in three slaughters from January to May 1994. At the three slaughter dates, LS lambs had heavier pre-slaughter liveweights and carcass weights than R lambs and were no fatter when adjusted to the same mean carcass weight. Net returns averaged more per LS cross lamb than per straightbred R lamb.

Wool growth responses in Drysdale and high and low staple tenacity Romney sheep to nutrient supplementation in autumn - Bray AR; Merrick NC; Smith MC; Scobie DR (Proceedings of the New Zealand Society of Animal Production, 1995)
With the increasing sensitivity towards the use of growth promoters in animal husbandry, the search is on for

Wool yellowing susceptibility: Heritability, genetic and phonotypic correlations with productive traits in Australian Merino, Corriedale and New Zealand Romney sheep - Benavides MV; Young MY; Beatson PR; Maher AP; Reid TC (Proceedings of the New Zealand Society of Animal Production, 1995)
Forty-two identical twinsets were milked either once (ODM) or twice (TDM) daily and offered pasture and silage, either to appetite (H) or restricted to 50-60% of this level (L) for the last 5 weeks of the 93/94 season. Pretreatment, uninfected cows produced 8.45+/-0.28 1 milk/d (mean +/- S.E) with a mean somatic cell count (SCC) of 37.1+/-3.3 x 10/3 cells/ml). Milk yields were significantly reduced (P<0.001) by L nutrition and by ODM. LogSCC was significantly increased (P<0.05) by L nutrition, due to reduced milk volumes but was not affected by ODM. Concentration of the serum-derived proteins, immunoglobulin G and bovine serum albumin, increased significantly for L nutrition and ODM. This suggests that involution had been accelerated in these animals, whose average daily milk yield was below 5 1/d. In late lactation milking should be discontinued for cows with milk yields of less than 5 1/d as involution may be initiated below this yield.

Accounting for scale effects in genetic evaluation of dairy cattle. - Lopez-Villalobos N; Garrick DJ; Harris BL; Blair HT (Proceedings of the New Zealand Society of Animal Production, 1994)
Lactation records of dairy cows calving between 1986 and 1989 were obtained from the Livestock Improvement Corporation of the New Zealand Dairy Board. There were milkfat yields from 2,004,854 lactations in 83,805 contemporary groups. The data were divided into three equal-sized subsets based on average level of production (scale) in the contemporary group; these being (kg milkfat ± sd) High (H), 172 ± 28; Medium (M), 152 ± 26; and Low (L), 139 ± 25. The objectives of this study were to provide evidence of heterogenous variance and to identify the best of three methods to stabilise the variance of milkfat yields for use in the genetic evaluation of New Zealand dairy cattle based on a best linear unbiased prediction procedure using an across breeds animal model which will be implemented in July 1996. The methods investigated for the accounting of scaling were adjustment based on: contemporary group standard deviation (SD); contemporary group means (MEAN); and logarithmic transformation (LOG) of milkfat yield. The overall correlation between contemporary group means and standard deviations was 0.44. This value was reduced to 0.31 in SD-transformed data, -0.27 (MEAN) and -0.24 (LOG). Correlations between breeding values for sires estimated from the independent data sets using a mixed model but without adjustment for scale were 0.76, 0.73 and 0.78 in the L-M, L-H and M-H comparisons. These were lower than expected correlations of 0.85, 0.85 and 0.87, reflecting inaccuracies in sire evaluation when scaling is ignored. Calculated correlations were similar for SD and MEAN (0.78, 0.75 and 0.80; 0.78, 0.74 and 0.78), but LOG reduced the calculated correlations (0.73, 0.69 and 0.75). Results confirm the problem of scaling on genetic evaluation of New Zealand dairy cattle and indicate other methods need to be studies to correct the scaling problem.

Animal Production in eastern Turkey - Thompson KF; Hart ND (Proceedings of the New Zealand Society of Animal Production, 1994)
AB: Subsistence village livestock farmers in the eastern provinces farm approximately 30% of the sheep and cattle of Turkey. Stock are housed for winter and grazed on communally owned and managed pastures for the remainder of the year. Typically farmers have 1 to 6 cows and 30 to 100 sheep or goats. A survey of 91 farmers showed that 55% of the cattle were of the local Anatolian breed and 37% were of exotic cross. Calving interval averaged 12.5 months, excluding the 10% barren cows. Female progeny were retained as herd replacements, males were sold between 8 and 18 months old to specialist cattle finishers who feed cattle indoors and aim to make a US$50 to US$120 margin per beast in a 4 to 6 month period. Sale of surplus lambs and milk products are the main sources of income for sheep farmers. Flocks averaged 80% to 100% lambing with lamb mortality ranging between 5% and 40%, depending on the level of winter feeding. Technology exists in Turkey for the improvement of winter feeding, and intensive lamb finishing, but technology transfer is constrained lack of experienced staff and limited training in livestock production of extension staff.

Anthelmintic resistance in the New Zealand Animal Production Industries - Watson TG (Proceedings of the New Zealand Society of Animal Production, 1994)
Enzymeimmunoassays (EIAs) for oestradiol-17b and progesterone were developed using antibody-coated microtitre plates, and steroid-horseradish peroxidase conjugates as steroid 'tracers'. The characteristics of standard curves and the precision of measurements were comparable between the EIAs and corresponding radioimmunoassays (RIAs). The applicability of the EIAs was demonstrated by using them to measure oestradiol-17b and progesterone concentrations in media sampled daily from cultures of bovine granulosa cells. The EIAs detected the characteristic switch in cellular steroidogenic capacity from oestradiol-17b to progesterone production typical of cultured granulosa cells. There was a significant linear correlation (P<0.001) between the EIAs and RIAs in the concentrations of steroids measured in granulosa cell culture medium by the two immunoassay formats. These findings may encourage other laboratories to consider converting "in-house" RIAs to EIAs, thereby eliminating the potential health and environmental hazards associated with the radioisotopes required for RIA.

Anti goat IGF binding protein 3 antibodies from chicken egg yolk - McLaren RD; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 1994)
The use of chickens for the production of highly specific antibodies to mammalian proteins offers a number of advantages over more conventional methods. Antibody responses to IGFBP-3 immunogen were apparent in the serum of chickens after only two inoculations with low levels of the immunogen. These specific antibodies subsequently appeared in the chicken egg yolk at levels of approximately 40% of those estimated in serum. A simple, rapid and reproducible two step method for the extraction and purification of the immunoglobulin fraction from egg yolk using octanoic acid is described. Relatively large quantities of specific antibodies can be obtained by these procedures. Egg yolk antibodies generated in this study will be used to develop an ELISA for measuring levels of IGFBP-3 in plasma and other body fluids. This approach is designed to overcome some of the difficulties associated with the use of ligand blotting analysis to quantify IGFBPs.

Biological efficiency: How relevant is this concept to beef cows in a mixed livestock, seasonal pasture supply context? - Morris ST; Brookes IM; Parker WJ; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
Efficiency, defined as the ratio of output to input, can be calculated for any product, and for any of the resources employed to generate that particular product. "Weight of calf weaned per unit cow liveweight" is commonly used to measure biological efficiency in the beef cow herd, based partly on the assumption that feed intakes and hence costs are related to liveweight. A more direct measure, and the one used here, is "weight of carcass produced per unit of feed intake". The biological efficiency of the traditional beef breeding cow, determined in this manner, is low compared to that of other beef cow systems (e.g. twinning cows, once-bred heifers). This is primarily because of the relatively low reproductive rate in traditional cow herds and the high proportion of annual feed consumption used to maintain the breeding female and her replacements. A simple output/input ratio may not, however, be appropriate for the mixed sheep and cattle systems which are widely used in New Zealand. For these systems, where a competitive or complementary relationship may exist between enterprises, a more complex efficiency ratio that contains elements of the whole farm system is likely to be more appropriate. Furthermore, in a seasonal pasture production system, where the supply of feed is likely to limit production at certain times of the year, feed does not have fixed value. Feed costs therefore become an important component of the efficiency equation. Utilisation by other livestock of a scarce resource (e.g. winter feed) is also likely to have an influence on the economic efficiency of the system. For example, if biological efficiency is ignored then output (weight of calf weaned) may be increased simply by increasing cow size but with no consideration of the extra feed inputs necessary to maintain larger cows, or the pressure that additional feed requirements may place on other components of the system at particular times of the year. In this paper, the relevance of biological efficiency is explored by comparing both biological and economic efficiencies of four cattle systems - traditional beef cows, beef x dairy cows (with and without twinning) and once-bred heifers - alone and in mixed sheep and cattle policies. We conclude that biological efficiency is a relevant concept, primarily because its components (carcass weigh and feed consumed) are also important determinants of economic efficiency. However marked differences between systems in the value of the carcass produced and/or feed consumed can lead to a poor correlation between the efficiency ranking of systems by biological and economic criteria.

Blood and urinary metabolites in cattle differing in susceptibility to bloat - Carruthers VR; Morris CA (Proceedings of the New Zealand Society of Animal Production, 1994)
Blood samples from 159 animals of known susceptibility to bloat were analysed for a range of proteins, minerals, acid base status, hormones and enzymes. Urine samples from the cows and heifers were analysed for minerals and osmolality. Each animal was sampled once only in a fed state. An increase in bloat breeding value of one unit (increasing susceptibility) was significantly associated (P<0.05) with a decrease in liveweight of 28 (±6) kg and increases in blood of 0.26 (±0.07) U/1 pepsinogen, 0.33 (±0.14) mmol/l urea, 29.5 (±11.3) nmol/1 Se, 4.9 (±1.2) mmol/l red blood cell K, 0.5 (±0.2) g/l beta globulin, and 13.9 (±6.1) pmol/l gastrin. The data suggest there may be some physiological or metabolic differences between high and low susceptible animals either arising during the selection and breeding programme or which contribute to the susceptibility mechanism.

Bovine growth hormone and its effects on the local production of prostacyclin I2 and mammary blood flow in dairy cows - Lacasse P; Block E; Couture Y; Petitclerc D (Proceedings of the New Zealand Society of Animal Production, 1994)
Our objective was to test the hypothesis that bovine growth hormone (bGH) can induce the secretion of vasodilators by the bovine mammary gland. Three adult lactating cows were surgically implanted with catheters in the left costoabdominal artery, in the left subcutaneous abdominal vein (milk vein) and in a lymph duct afferent to the left supramammary lymph node. In addition, a transit time flow probe was implanted on the left pubic artery. Cows were injected s.c. with either saline or 25 mg of bGH according to a crossover design. Samples from arterial and venous blood and from lymph fluid were collected from 2 hours before to 16 hours after the injection. Mammary blood flow was recorded at each sampling. Injection of bGH induced a gradual increase in mammary blood flow in lactating cows while it remained constant after the saline injection. Venous concentrations of 6-keto-prostaglandin F1a, a stable metabolite of the vasodilator prostacyclin I2, were not affected by bGH injection. However, lymphatic concentrations of the prostacyclin I2 metabolite increased when cows were injected with bGH. The time course of the increase in plasma IGF-I concentration was similar to that of mammary blood flow and 6-keto-prostaglandin F1a. In conclusion, a local release of prostacyclin I2 may be responsible for the bGH-induced increase in mammary blood flow. IGF-I might mediate this effect of bGH.

Cadmium accumulation in liver and kidney of sheep grazing ryegrass/white clover pastures - Lee J; Grace ND; Rounce JR (Proceedings of the New Zealand Society of Animal Production, 1994)
Pastures growing on soils fertilised with phosphatic fertilisers accumulate cadmium (Cd) in their plant tops in proportion to substrate concentrations. Sheep grazing pastures absorb some of this Cd. To quantify the rate with which Cd is accumulated in sheep tissue, three replicated 0.4 ha blocks were fertilised with either 333 kg/ha of single superphosphate only (control) or amended with CdSO4 to give 274g Cd/ha (high-Cd), and set stocked with 10, three months old Romney wether lambs. Cadmium (Cd) concentrations were determined in liver, kidney, proximal duodenal and skeletal muscle tissue of sheep, ingesting either (means ± s.e.) 266±22 (control) or 746±58 (high-Cd) ug CD/day from three to six months or 290±21 and 721±72 ug Cd/day over six to eighteen months. Cadmium concentrations in kidney and liver tissue increased markedly over the first three months: 0.042±0.006 to 0.32±0.03 (Control) and 0.57±0.04 (high-Cd) ug Cd/g fresh tissue, and 0.04±0.006 to 0.12±0.02 (Control) and 0.31±0.06 (high-Cd) ug Cd/g fresh tissue, for kidney and liver respectively. Although total Cd content continued to increase, as organ size increased, over the next 12 months daily accumulation rates in both tissues were much lower compared with those over the first three months. For example, daily Cd accumulation in kidney decreased from 0.25±0.002 to 0.06±0.01 and 0.47±0.04 to 0.32±0.05 (ugCd/d) for sheep from the control and high-Cd pastures respectively. Total Cd content in kidney and liver combined accounted for approximately 0.25% of total Cd ingested by sheep age three to six months but this significantly decreased to 0.1% in sheep age six to eighteen months. At higher Cd intakes increased metallothionein protein synthesis in kidney and liver tissue enabled animals to be more efficient in sequestering Cd. This resulted in reduced accumulation of Cd in muscle tissue of sheep on the high- Cd pastures (2.0±0.04 and 5.0±0.08 ng Cd/g) compared with those grazing the control pasture (4.0±0.6 and 14±5 ng Cd/g) in animals from the first and second periods respectively. The results from this study show that it is the first few months after weaning that fastest uptake into kidney occurs and therefore strategies to reduce Cd absorption and subsequent accumulation, e.g. by increasing zinc in the diet, should focus on young animals.

Carcass, liver and kidney characteristics of lambs grazing plantain (Plantago lanceolata), chicory (Cichorium intybus), white clover - Deaker JM; Young MJ; Fraser TJ; Rowarth JS (Proceedings of the New Zealand Society of Animal Production, 1994)
Plaintain (Plantago lanceolata L.) is being evaluated in New Zealand as a potential pasture species because of its supposed medicinal attributes. Seventy six, four month old Coopworth ram lambs were rotationally grazed on either plantain (PL), chicory (Cichorium intybus L.; CH), white clover (Trifolium repens L.; WC) or perennial ryegrass (Lolium perenne L.; RG) for 82 days from January to April, 1993 at an allowance averaging 1.8 kg green DM/lamb/day. At slaughter treatment differences in carcass weight were apparent (16.8, 18.3, 20.1 and 15.6kg, respectively, for PL, CH, WC and RG). After adjustment for body size no differences in carcass characteristics were apparent between treatments. However, differences still existed for liver and kidney size. WC lambs were the heaviest at slaughter and had the largest livers after adjustment. In contrast, kidney size did not follow liveweight with PL lambs having the largest kidneys after adjustment. Serum urea and creatinine levels indicate that renal function was not impaired in PL lambs relative to RG lambs.

Characterization and regulation of cationic amino acid transport in bovine mammary epithelial cells - Brief Communication - Kiaei M; Prosser CG; Grigor MR (Proceedings of the New Zealand Society of Animal Production, 1994)
No abstract supplied

Chiapas sheep - wool production and animal health in a unique sheep breed - Perezgrovas R; Parry A; Peralta M; Zaragoza L; Trow D; Pedraza P (Proceedings of the New Zealand Society of Animal Production, 1994)
In the Highlands of Chiapas, in southern Mexico, over 10,000 Indian families from the Tzotzil-speaking group manage small flocks of Chiapas sheep, a unique local breed. Sheep flocks are managed by the Indian women with all animal health care based on traditional herbal remedies. The University of Chiapas (UNACH) is conducting a research programme to investigate the biological basis of traditional sheep husbandry systems and to improve wool production. Animal health research tested the effectiveness of some common herbal remedies. In 4 sheep flocks, garlic (Allium sativum) and Mexican tea epazote (Chenopodium ambrosioides) were administered orally either separately or together. The most effective treatment was the combined 5g garlic + 5g epazote, which significantly reduced (P<0.01) the number of eggs of gastrointestinal nematodes by 66 ± 8% and 61 ± 28% at 1 and 2 weeks after treatment. Reductions in Eimeria spp. oocysts by 43% in 2 different treatments (5g garlic at 3 weeks post-treatment and 5g garlic + 5g epazote at 2 weeks post- treatment) were just below the accepted 50% effectiveness level. These preliminary results have clarified the need for controlled research trials, testing dose rate and frequency of these herbal treatments. Three colour phenotypes of Chiapas sheep have been identified: W-white, BL- black and BR-brown. Wool is subjectively graded by shepherdesses as good (G), medium (M) or poor (P) and 12 month fleece weights show differences between the wool grades - mean annual fleece weight (kg) was higher (P<0.01) for G (1.38±0.10) than P (0.95±0.10) with M intermediate (1.11±0.10). Twenty-seven sheep were examined with the aim of determining which objective fibre characteristics were used in the subjective assessment of wool grade. Mean fibre diameter was coarse (35.7 microns) and did not differ between wool grade or colour phenotype. Staple length differences (mm) were highly significant (P<0.001) between G, M and P (97.3 vs 77.6 vs 63.4) but not colour phenotypes. Kemp levels (%) were higher (P<0.001) for BL (10.24±1.4) vs W (2.32±1.4) and BR (2.19±1.4); and % medullation for BL was 12.14 (P<0.02) compared to 5.19 and 2.77±1.87 for W and BR respectively. These results show that the most consistent fibre characteristic distinguishing the different wool grades is staple length of the long fibres, which could be related to differences in seasonal fleece growing patterns. The results for fibre characteristics differences between colour phenotypes has helped to objectively characterise these phenotypes and provided a valuable insight into the general fibre characteristics of Chiapas sheep.

Comparative performance of Angus cattle and swamp buffalo fed ad libitum either a lucerne hay and concentrate ration or pasture hay. - Thomson NA; Death AF; Power MT (Proceedings of the New Zealand Society of Animal Production, 1994)
Voluntary intake and liveweight gain of Angus cattle (CAP) and swamp buffalo (B) were compared on 2 feeds; ad lib., lucerne hay (L) + 1 kg concentrate/animal/day (LC) and ad lib. pasture hay (P) in a 2 x 2 Latin square designed trial. The two hays had similar ME values; L, 8.5 and P 8.7 MJ/ME/kg DM, but differed (P<0.05) in protein content; L, 14.6% and P 10.1%. The concentrate was 13.5 MJ ME/kg DM and 14.1% protein. Animals were fed in a feed-lot with individual pens/treatment. Intake was assessed on a group basis for all treatments and individual animal intake was assessed for the P treatments only using slow release chromium capsules. Two, 4 week experimental periods were preceded by a 2 week feed adjustment period. Liveweight gains showed a species x fed interaction (P<0.001) with individual treatment gains (kg/day) of; 0.80, -0.54, -0.02, -0.09 for CLC, CP, BLC, and BP groups respectively. Cattle consumed (group assessment) more (P<0.05) L Hay than buffalo; 127 vs 99 g DM/kg LWT0.75. The intake of P hay was similar for each species; 102 and 100 g DM/kg LWT0.75 for C and B respectively. The release of CR2O3 from the capsules were similar for the two species (1.56 g/day). Intakes of P hay assessed by the marker techniques differed (P<0.05); 100 and 88 g DM/kg LWT0.75 for the CP and BP treatments respectively. The difference in performance of the two species on P may have been the result of the marginal (for cattle) protein levels. No explanation is given for the poor performance of buffalo on the LC ration.

Comparison of methods for measuring fibre diameter of Romney Wool - Scobie DR; Merrick NC; Saville DJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Wool from lines of Romney sheep selected on the basis of staple strength was measured for mean fibre diameter using both the airflow apparatus and an Optical Fibre Diameter Analyser (OFDA). For wool from "low strength" and "control" selection lines, airflow measurements tended to be upwardly biased in relation to the OFDA measurements, while for wool from the "high strength" line the airflow measurements tended to be downwardly biased. Two sources of bias are known in the literature, medullation and standard deviation. In this work the latter seemed to be more important, which may be a consequence of the relatively low level of medullation present in these wools (8.6%). For research work the OFDA is put forward as the preferred instrument.

A comparison of the carcass and meat quality of Awassi-cross and Texel-cross ram lambs - Holloway IJ; Purchas RW; Power MT; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 1994)
The Awassi is a fat-tailed sheep breed from the Middle East that has recently been imported into New Zealand for live-sheep export and for milk production. The aim of the current trial was to compare the carcass and meat quality of Awassi-cross and Texel-cross ram lambs. There were 36 lambs in each sire-breed group with an equal number from Romney and Poll Dorset ewes. Lambs were allocated at random within breed-cross groups to groups of 9 that were slaughtered in either May or August to give an overall mean carcass weight of 19.7kg. The Awassi-sired group had a lower dressing-out percent (44.4 vs 44.8; P<0.01), similar GR tissue depths (7.6 vs 8.4 mm) but more weight-adjusted leg fat (537 vs 446g. P<0.001). The most clear-cut difference was in carcass shape with Awassi-cross lambs having longer carcasses (1068 vs 1013 mm), longer legs, and longer, heavier leg bones at a constant carcass weight (all P<0.001). The shape difference at a common carcass weight was also reflected in the Awassi-cross lambs having lower leg muscle to bone ratios (3.49 vs 3.88), muscle weight (2047 vs 2172 g), and muscularity values (0.436 vs 0.488) than the Texel-cross lambs, and shallower longissimus muscle depths (28.0 vs 29.8 mm)(all P<0.01). Differences between Awassi and Texel-sired lambs in tenderness (shear values) and colour (L*,a*,B* values) of the semimembranosus muscle were not significant. Differences between dam-breed groups were generally small, although, relative to the Poll Dorset, the Romney-cross group had lower weight-adjusted longissimus depths (28.2 vs 29.6 mm) and leg muscle to bone ratios (3.57 vs 3.80(both P<0.01). When adjusted to the same carcass weight, lambs slaughtered in August had lower dressing-out percentages (42.6 vs 46.6), lower GR depths (6.7 vs 9.3 mm, longer carcasses (1063 vs 1018 mm), and poorer leg muscularity (0.450 vs 0.474) than those slaughtered in May (all P<0.02). In this study Awassi-cross carcasses were inferior to those of Texel-cross lambs in terms of composition and shape, but differences in meat quality not apparent.

The complementary contribution of the beef cow to other livestock enterprises - McCall DG (Proceedings of the New Zealand Society of Animal Production, 1994)
This paper reviews potential benefits of beef cows to other livestock enterprises on a sheep and beef farm. These benefits may include general benefits of cattle such as improved sheep performance via improved pasture quality. They may also include benefits specific to cows such as the efficient use of low quality feed and feed demand patterns which match pasture production. A linear programming model is used to quantify complementary benefits of breeding cows to the total farm economy. This is done by comparing the profit from finishing only policies with those that include breeding cow and finishing cattle policies. When the marginal benefit in farm profit is all attributed to the breeding cows their worth is between 5 and 26% greater than estimated by an enterprise analysis which does not account for complementarity. However, complementary benefits cease when returns from finishing reach $16/su greater than cows. Field system trials are required to validate these conclusions.

Current and emerging reproductive technologies for beef breeding cows. - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1994)
Reproductive technologies may be defined as any technology which impacts on the reproductive potential of the herd. Reproductive technologies applicable to beef breeding cows can broadly be classified into those requiring either a low, medium or high technical input. The examples of 'Low Technology' options discussed are: age at first joining, breed/cross or strain of cow, time of calving, and pregnancy diagnosis. In traditional breeding cow herds, cow productivity can be increased by modest amounts (5-10%) if only single-option 'low tech' changes are implemented. However, these fundamental technologies need to be well developed before higher technologies can be successfully applied. Two examples of 'Medium Technology' strategies that have been available for some time include oestrous synchronisation and multiple suckling. Oestrous synchronisation has the potential to facilitate an increase in the number of herds adopting yearling heifer mating. Twin suckling through fostering an additional calf has been demonstrated to significantly increase the number of calves weaned per cow. Emerging 'High Technology' options include: twinning, controlling the sex of calves at conception and cloning. Future developments in embryo technologies are vital in many of the emerging reproductive technologies for beef cows.

The current status of the beef breeding cow in New Zealand mixed livestock production systems. - Webby RW; Thomson RD (Proceedings of the New Zealand Society of Animal Production, 1994)
The total beef breeding cow herd in New Zealand, currently numbers 1.45 million head. Of the total beef herd, breeding cows make up only 30%. In 1975 when numbers peaked at 2.31 million, breeding cows made up 37% of the total beef herd. Despite the decline in the New Zealand breeding cow herd, beef production now exceeds 1975 levels. Per head carcass weights have increased and there is an increasing contribution of beef cattle from the dairy industry. Pastoral land loses to forestry are expected to exceed 500,000 ha in the next decade, much of this from areas grazed by breeding cows. The beef breeding cow is complementary to the performance of other stock classes. Her seasonal feed demand profile, her ability to utilise surplus often low quality feed, buffer herself against periods of low feeding and to be a source of equity and income stabilisation is highly regarded by farmers. Compared to a traditional self replacing beef breed herd, a dairy beef cross breed herd where all replacements are sourced from the dairy industry will return up to 43% more revenue per hectare. With the development of new technology there is growing potential for the beef breeding cow to compete at all levels of the beef production line.

Determining the number of calves in early pregnancy using real-time ultrasound imaging in beef cows induced to twin. - McMillan WH; Oakley AP; Hall DRH (Proceedings of the New Zealand Society of Animal Production, 1994)
Details of the timing of pregnancy loss following induced twinning are unknown. The aim of this study was to evaluate real-time ultrasound as a method of determining early pregnancy status (0, 1 or 2 foetuses) in beef cows induced to twin using AI and ET. A 7.5 Mhz ultrasound probe was used intra- rectally to count foetuses in 2 experiments. In Exp. 1, 57 heifers were examined between 25 and 60 days of pregnancy and then slaughtered. In Exp. 2, up to 103 cows were examined between Day 25 & 60 of pregnancy, and final pregnancy status was confirmed using calving records. In Exp. 1, the accuracy of Day 25, Day 45 and Day 60 predictions of 2 foetuses was 100%, 20% and 100%, and 1/24, 5/33 and 1/33 twin pregnant heifers were predicted. The accuracy of correctly predicting twin outcomes was 33, 50 and 33% at the same 3 stages of pregnancy, but only 3, 2 and 3 twin pregnancies occurred, respectively. In Exp. 2, there was generally little difference between the accuracy of predicting twin pregnancies and the accuracy of the prediction. Thus, at Day 25, 35 and 45 and 60, the accuracies were approximately 20, 47, 52 and 45%. Twenty recipients eventually calved twins. We conclude that real-time ultrasound imaging up to Day 60 is not an accurate technique for determining twin pregnancy status of cows. Loss of concepti between scanning and term did contribute substantially to this poor result in Exp. 2, but not in Exp. 1.

The effect of block and paddock grazing in winter on cow behaviour, cow performance and herbage accumulation - Judd TG; Thomson NA; Barnes ML (Proceedings of the New Zealand Society of Animal Production, 1994)
Two management methods for wintering dry cows on pasture (block and paddock) were compared at the Taranaki Agricultural Research Station over a 45 day period. Treatment effects on aggressive behaviour, grazing behaviour and liveweight gain were measured in addition to effects on pasture treading damage and subsequent herbage accumulation. The block grazed group had an area of 25 m2/cow/day, and were confined to a new area (0.1 ha) of pasture each day. The paddock grazed group had an area of 125 m2/cow/day, grazing the total paddock area (0.5 ha) over five days. There were 32 cows and 8 heifers in each treatment group. Agonistic activity in the paddock group was 50% lower in week one and 28% lower in week six, than the block group. Paddock cows and heifers gained more liveweight (p<0.01) than block cows and heifers; 0.22 and 0.24 kg/animal/day more respectively. Herbage accumulation over the subsequent three months (July - September) was 290 kg DM/ha lower (p<0.05) on the paddock grazed areas compared to block grazed areas. Paddock grazing reduced agonistic activity among heifers and cows and gave higher liveweight gains. Some of this advantage could possibly be negated by lower herbage accumulation in the subsequent three months.

Effect of breed on plasma carotene concentration in New Zealand dairy heifers - Newman S-AN; Knight TW; O'Neill KT; Death AF; Ridland M (Proceedings of the New Zealand Society of Animal Production, 1994)
Factors affecting plasma carotene concentration were investigated in New Zealand dairy heifers. Blood samples were collected from 4000 dairy heifers in spring in November 1992. Significant (P<0.001) variation was found in plasma carotene concentrations due to region, breed and farm. Values for individual cows ranged from 1.7 to 56.2 ug/ml. Purebred Jersey heifers had the highest plasma carotene levels (18.2 ± 0.4 ug/ml), purebred Friesians the lowest (14.4 ± 0.2 ug/ml), crossbreds were intermediate with 50% Jersey and 50% Friesian significantly different from the purebreds (16.9 ± 0.6 and 15.4 ± 0.4 ug/ml respectively).

Effect of contrasting spring grazing management on summer-autumn pasture and milk production of mixed ryegrass-clover dairy swards. - Da Silva SC; Hodgson J; Matthews PNP; Matthew C; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 1994)
Research at Massey University has shown that a spring grazing management laxer than the conventional intensive grazing allowing some early ryegrass seedhead development before close grazing at anthesis ("Late Control") may result in improved summer-autumn pasture production. Comparisons between conventional and late control spring grazing managements for dairy cows were carried out, on a paddock scale, during 1992/93. Late control swards showed enhanced dry matter production before (24.5% increase - P<0.05) and after (32.0% increase - P<0.10) the control grazing in early December. Concomitant measurements of animal performance revealed that the increased pasture production during the summer-autumn period could be effectively converted into milk by dairy cows, and resulted in an increase in milk-solids production of about 10% per cow (P<0.10). The implications of these results to dairy management systems are discussed in the context of pasture responses to spring management and alternative conservation strategies.

The effect of different perennial ryegrass cultivars on dairy animal performance - McCallum DA; Thomson NA (Proceedings of the New Zealand Society of Animal Production, 1994)
A study at the Taranaki Agricultural Research Station investigated possible limitations to dairy production due to recently released ryegrass cultivars. Dairy animals grazed pure swards of either Yatsyn-1, Embassy, Vedette or Pacific in a series of three trials from February 1992 to April 1993. Three ryegrass cultivars (Yatsyn-1, Embassy and Vedette) were infected with the endophyte Acremonium lolii. Pacific was infected with an Acremonium endophyte, strain 187B. In trial 1 (autumn 1992) liveweight gain of dairy calves grazing the respective cultivars over eleven weeks were monitored. Trial 2 (spring 1992) and trial 3 (summer/autumn 1993) were each conducted over 3 consecutive 8 day periods using dairy cows. Liveweight gain and ryegrass staggers were monitored in trial 1, and milk volume and composition in trials 2 & 3. Herbage mass before and after grazing, dry matter disappearance, botanical composition, lolitrem b, in-vitro digestibility and crude protein levels were measured on each occasion, and ergovaline levels in trial 3. Ryegrass cultivar had no effect on calf liveweight gain. Ryegrass staggers were encountered in calves grazing Yatsyn-1, Embassy and Vedette but not in Pacific. In spring and in February and March of the summer/autumn trials, ryegrass cultivar had no effect on milk production or composition. Milksolids production from Yatsyn-1 was lower (P<0.05) than from Vedette and Pacific in April. Lolitrem content of Pacific was lower (0.14 ug/g grass) and ergovaline content higher (0.99 ug/g grass) in comparison to the other ryegrasses. There was no difference between cultivars in pasture utilisation, botanical composition, digestibility or crude protein levels. It is concluded that ryegrass cultivar or endophyte strain had little effect on dairy animal performance.

Effect of level of nutrition and season on fibre growth in alpacas - Newman S-AN; Paterson DJ (Proceedings of the New Zealand Society of Animal Production, 1994)
The effect of nutrition on fibre production varies with species and response to nutrition may also be influenced by season. This study examined the effect of feed allowance and season on fibre growth in alpacas. 14 one- year-old alpacas were pen-fed a pelleted lucerne diet at a maintenance or ad lib intake level for 11 weeks in summer (January - February) and winter (July - September). Intake, liveweight gain and fibre growth rate were measured. Voluntary feed intake was 45% higher in summer than in winter, 68 vs 47 ± 2 g DM/kg0.75/day. Estimated maintenance requirements from this trial were 31.11 g DM/kg0.75/day or 0.276 MJ ME/kg0.75/day. There was a positive relationship between feed intake, liveweight gain and fibre growth rate. Increased feed allowance resulted in higher liveweight gain and increased fibre growth rate. Differences in fibre length growth between maintenance and ad lib feeding levels, 0.36 and 0.33 ± 0.02 mm/day respectively, were not significant (P=0.07). Feeding level had no effect on fibre diameter. Fibre growth rate was greater (0.77 vs 0.62 ± 0.04 mg/cm2/day) and fibre diameter coarser (33.7 vs 31.3 ± 0.9 µ) in summer than winter. The rate of response of fibre growth to increased feed allowance was the same in summer and winter.

The effect of long-day photoperiod treatments on plasma prolactin and wool follicle activity in New Zealand Wiltshire sheep - Craven AJ; Parry AL; Wildermoth JE; Pearson AJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Exposure of NZ Wiltshire sheep to a long-day photoperiod during late winter/spring has previously been shown to alter wool follicle growth patterns. The present experiment was undertaken to evaluate the plasma prolactin and wool follicle response to treatment with either 1, 2 or 3 months of long days. Four groups of six, NZ Wiltshire ewes were subjected to long-day photoperiod (16L:8D) for 1 month (LD1), 2 months (LD2), 3 months (LD3) or natural photoperiod (control), commencing on the 3 August, after which they were released from light treatment into natural (indoor) spring daylength. Weekly jugular blood samples were assayed for prolactin (PRL) and skin biopsies were histologically assessed for wool follicle activity. Circulating PRL concentrations were low in all treated and control sheep at the start of the experiment (19 ± 2 ng/ml). In treated sheep mean PRL concentration increased (P<0.05) above control levels (8 ± 1 ng/ml) within 1 week after exposure to long days (52 ± 4, 51 ± 5 and 55 ± 2 ng/ml for LD1, LD2 and LD3, respectively). PRL concentrations remained significantly higher than controls (P<0.05) for the duration of each treatment reaching maxima of 148 ± 27 ng/ml, 180 ± 43 ng/ml, and 199 ± 33 ng/ml for LD1, LD2 and LD3 respectively. In LD2 and LD3 treatments, PRL concentrations declined to control levels by 3 and 2 weeks after treatment had ceased, respectively, but in the LD1 treatment PRL remained significantly above (P<0.05) control levels until between 2 and 3 months after treatment. Primary follicle activity (PFA) decreased in response to long-day treatment (P<0.01) reaching minima of 47 ± 9%, 36 ± 6%, and 33 ± 11% in LD1, LD2, LD3 sheep, respectively. Secondary follicle activity (SFA) responses were most marked in the LD2 and LD3 treatments where they fell below (P<0.05) control levels reaching minima at 2 months into treatment (66 ± 15% and 58 ± 13% for LD2 and LD3, respectively). Both PFA and SFA increased to over 90%, within 1 month after release into natural light, in all treatments groups (except PFA for the LD1 group which took 2 months after release to reach over 90%). In support of previously reported trials an increasing level of plasma PRL was followed by a decline in follicle activity. The optimal time frame to achieve an effective synchronised follicle regression was between 2 and 3 months of long- day treatment. The long-day treatment system produced a complete follicle growth cycle in temporal synchrony and is therefore a potential model for the investigation of structural and biochemical processes surrounding transitions between active and resting stages of fibre growth.

The effect of manipulation of plasma prolactin concentration on cashmere growth in spring - Litherland AJ; O'Neill KT (Proceedings of the New Zealand Society of Animal Production, 1994)
Domperidone was administered to cashmere goats at 2.5 mg/day either by a daily subcutaneous injection at 1000 hours (INJ, n=6) or by a subcutaneously fitted osmotic minipump (OSP, n=6). There was an untreated control group (C, n=5). The treatments commenced on 13 September 1991 and continued for 14 days. Daily plasma prolactin concentrations at 1200 hours measured across the 14 days of treatment were 612±32, 73±35, and 60±34 ng/ml in INJ, OSP and C groups respectively (P<0.001), while daily plasma PRL concentrations at 1000 hours, immediately prior to the injection, were 33±6, 72±7 and 60±8 ng/ml in INJ, OSP and C groups respectively (P<0.01). Mean downlength was lower in INJ goats (34±4mm) than OSP goats (51±4mm) and C goats (46±4mm). A greater percentage of fleece by weight was shed earlier (P<0.05) in INJ compared to the C group. Primary follicle activity also increased earlier (P<0.001) in INJ goats when compared to C and OSP goats. There was no effect of OSP on fibre growth and no overall effect of INJ on guard hair length, shedding score, presence of newly erupted cashmere fibres, and secondary follicle activity. In conclusion, DOM administered at 2.5 mg/day for 14 days by injection, but not by osmotic pump, perturbed fibre growth in primary and not secondary follicles.

Effect of nutrition on fine wool production in Merino wethers - Newman S-AN; Paterson DJ; Haack NA (Proceedings of the New Zealand Society of Animal Production, 1994)
The potential to reduce fibre diameter of wool from Merino sheep using feeds that are readily available and cheaply produced in New Zealand was investigated. Two hundred and twenty fine wool two year old and mature Merino wethers were allocated to four feeding treatments for 12 months. The four feeding treatments were 1) silage, 2) silage and grass, 3) grass allocated three times per week, and 4) grass allocated once per week. Monthly liveweight, wool growth rate and fibre characteristics were measured. At the trial conclusion annual fleece production was determined and wool samples from each treatment group combined for line analysis. Liveweights fluctuated over the trial period indicating the difficulty of controlling feed intake accurately under pasture conditions. Wethers on the silage treatment had significantly lower fleece weights (2.4 kg) and finer fibre diameter (17.0 ± 0.2 and 17.6 ± 0.3 m for 2 year old and mature wethers respectively) than other treatments (3.2 kg, 17.6 ± 0.2 and 18.6 ± 0.3 µ for 2 year old and mature wethers respectively). Staple strength ranged from 17 to 36 N/ktex, with weakest wool from the silage treatments. Bulk values were low, ranging from 24.0 to 27.3 cm3/g. Wool was processed by a Japanese company for super high grade men's clothing fabric. The treatment groups were processed separately and evaluated at all stages from greasy wool to fabric. Little difference was found between the treatments except for the wool from the young silage treatment which had a superior fabric handle but was inferior at other processing stages.

Effect of once daily milking and concurrent somatotropin (bST) on production and mammary tight junction permeability in cows - Brief Communication - Stelwagen K; Davis SR; Farr VC (Proceedings of the New Zealand Society of Animal Production, 1994)
No abstract supplied

The effect of pasture height on herbage intake and ewe production under continuous stocking management during the autumn. - Burnham DL; Parker WJ; Morris ST (Proceedings of the New Zealand Society of Animal Production, 1994)
A replicated trial design with ewes continuously stocked on mixed ryegrass/white clover pastures at three target sward surface heights (SSH) of 4, 6 and 8 cm, and 16 ewes per sward treatment (total 96 ewes), was carried out from February through to April 1993. Herbage intake was assessed indirectly from faecal output measured using chromium controlled release capsules and the in vitro digestibility of herbage samples obtained from oesophageal- fistulated sheep run with the ewes. Intake measurements were taken before and after the rams were joined with the ewes. Pasture measurements for the 4, 6 and 8 cm SSH treatments were: SSH, 4.12 vs 6.18 vs 7.97 cm (PSE 0.54 cm, P<0.05); mass, 3358 vs 4291 vs 5231 kg DM/ha (PSE 389 kg DM/ha, P<0.1); dead mater content, 38.9 vs 26.7 vs 40.4% (PSE 5.8%, NS); and organic matter digestibility, 68.0 vs 71.9 vs 63.8% (PSE 1.21%, P<0.0001). Organic Matter (OM) intakes fro the 4, 6 and 8 cm SSH treatments were 1.39 vs 1.86 vs 1.06 kg OM/ewe/day (PSE 0.08 kg OM/ewe/day, P<0.05) for the pre-mating intake and 1.26 vs 1.34 vs. 1.09 kg OM/head/day (PSE 0.06 kg OM/ewe/day, NS) for the mating intake period. Production responses of the ewes for the 4, 6 and 8 cm SSH treatments were: liveweight gain, 72 vs 83 vs. 73 g/day (PSE 5 g/day, NS); and wool growth rate, 1.37 vs 1.44 vs 1.42 mg/cm2/day (PSE 0.03 mg/cm2/day, NS). These results suggest that, in the autumn, maximum herbage intake and ewe performance on ryegrass - white clover pastures can be obtained at a sward height of about 4 cm, and that pasture digestibility and dead matter content in the pastures are the major limiting factors at this time of year.

The effect of peripartum administration of ovine prolactin on lactogenesis in autumn-lambing ewes. - Peterson SW; MacKenzie DDS; McCutcheon SN; Lapwood KR (Proceedings of the New Zealand Society of Animal Production, 1994)
Two routes of oPRL supplementation were used to elevate peripheral or local concentrations of PRL in autumn-lambing ewes which, based on previous results, were expected to have low plasma PRL concentrations and milk yields relative to spring-lambing ewes. Administration of 10 mg oPRL directly into the gland or subcutaneous injection of 0.5 mg/kg oPRL did not increase the milk yields, or change the composition of milk, compared to controls. These results suggest that the circulating and intramammary concentrations of PRL in autumn-lambing ewes are not limiting lactogenesis. However, because the plasma prolactin concentration in the ewes was unexpectedly high, it was not possible to reach firm conclusions regarding possible effects of supplementary oPRL in ewes with naturally low plasma PRL concentrations. Nevertheless, the results indicate that raising the intramammary concentration of PRL around the time of parturition, in ewes with circulating PRL concentrations characteristic of normal spring-lambing ewes, does not enhance lactogenesis.

Effect of selection for greasy fleece weight on the components of fleece weight in New Zealand Romney sheep - Liu AH; Wickham GA; Blair HT (Proceedings of the New Zealand Society of Animal Production, 1994)
Variation in the clean fleece weight (W) between ewe hoggets born in 1988 from the Massey University fleece weight selected (FW) and control (C) flocks was related to variation in four components: predicted skin surface area (S), mean number of fibres (follicles) per unit area of skin (N), mean fibre cross-sectional area (A) and mean staple length (L). Mean W (±pse) was 3.34 and 2.48 ± 0.07 kg for the FW and C lines, respectively. Of the components, L (147 and 126 ± 3.1 mm; P<0.001), N (29.6 and 27.0 ± 0.83 fibres/mm2; P<0.05) and A (1096 and 1002 ± 28.0 µm2; P<0.05) were significantly greater in the FW line (n=27) when compared to the C line (n=22). The difference in W between the two lines was apportioned into contributions from the various components using the percentage deviation technique. The influence of combined components, wool weight per unit area (N x A x L), fibre volume (A x L) and total number of fibres (S x N) on W was also examined. The most important contributor to the difference in W between lines was L with A and N being less important; the contribution of S was relatively small. Wool weight per unit area had far more influence on between line differences in W than wool growing surface area (S) and fibre volume was more important than the total fibre number. Attempts were also made to assess the relative importance of the components of fleece weight between sheep within each line. The standardised partial regression coefficients of log transformed values of each component on W were; for the selected line, L = 0.26, A = 0.36, N = 0.16, S = 0.38; for the control line, L = 0.08, A = 0.58, N = 0.45, S = 0.53. High values of S relative to the other components of W suggest that the size of animal is more important in determining the phenotypic differences in fleece weight within the line than the genetic differences between lines.

The effect of whole body cysteine supplementation on cysteine utilization by the skin of a well-fed sheep - Harris PM; Lee J; Sinclair BR; Treloar BP (Proceedings of the New Zealand Society of Animal Production, 1994)
Research, in both New Zealand and Australia, is being directed towards enhancing the sulphur amino acid supply of sheep by either plant or animal modification. This study investigated the effects of such improved systeine supply in well-fed sheep on both whole body and skin metabolism of cysteine.. The level of cysteine supplementation chosen (2g/d) represented about a 50% increase in absorbed cysteine. Cysteine was supplied by jugular infusion to avoid loss during gut absorption. At this level of cysteine supplementation a preliminary trial on sheep fed either 700 g or 1250 g lucerne chaff showed no significant effect on wool production but a significant increase in wool sulfur (S) concentration over a one month period of treatment. In a second trial, two groups of five, 40kg, cryptorchid Romney sheep were offered 1200 g/d of lucerne chaff and one group was supplemented with 2g/d cysteine for five days prior to measurement, with the other group receiving saline only. Cysteine supplementation increased whole body cysteine utilization (irreversible loss of 35S-cysteine) from 4.7 ± 0.4 to 6.4 ± 0.3 g/d, while appearance of 35S-cysteine in the oxidation pool increased by 37%. Cysteine supplementation resulted in an increase in circulating cysteine concentration (33.8 ± 5.6 to 51.1 ± 12.0 µM) but blood flow to the skin patch (measured by dye dilution) was reduced from 0.29 ± 0.03 to 0.21 ± 0.02ml. min-1.g-1 skin. Hence the cysteine flux through the skin (blood flow times concentration) was unchanged. Nevertheless uptake of 35S-cysteine by the skin increased with supplementation from 12.8 ± 2.7 to 22.8 ± 2.7%, resulting in a significant increase in skin utilization of cysteine for protein synthesis. The results suggest that enhancing cysteine supply within the sheep does not proportionately improve cysteine availability for protein synthesis. Instead a large proportion of the extra supply is oxidised. Additionally, although enhanced whole body cysteine supply does not improve skin cysteine supply (or flux), increased arterial cysteine concentration appears to stimulate skin cysteine transport into cells so that increased cysteine utilization for protein synthesis is still achieved.

The effect on oesophageal groove closure of water and mineral solutions drenched to cows - Carruthers VR; Phipps DE; Bakker RJ (Proceedings of the New Zealand Society of Animal Production, 1994)
The fate of mineral solutions when drenched was assessed in cows slaughtered after drenching using a dye visible in gut contents. Seven groups of 10 cows were drenched with water or solutions of magnesium oxide, magnesium chloride, magnesium sulphate, sodium chloride, sodium bicarbonate or zinc oxide in Trial 1. Frequency of closure was higher (P<0.05) for sodium bicarbonate (60%) than for magnesium oxide or magnesium chloride (10 to 20%). Five cows drenched with water alone showed bypass of the rumen. In Trial 2 four groups of 6 or 7 cows were drenched with water or solutions containing selenium. Hydromin or copper sulphate. Frequency of closure was higher (P<0.05) for copper sulphate (70%) than for water or selenium (0%). The results suggest that bypass of the rumen in response to drenching may contribute to apparent failures of bloat drenches, particularly when certain minerals are added to the drench.

The effects of condensed tannin in Lotus corniculatus upon nutrient metabolism and upon body and wool growth in grazing sheep. - Wang Y; Waghorn GC; Douglas GB; Barry TN; Wilson GF (Proceedings of the New Zealand Society of Animal Production, 1994)
Lotus corniculatus containing 23 g/kg DM of extractable condensed tannin (CT) and 35 g total CT/kg DM was fed to sheep in two experiments. In both experiments half the sheep received supplementation with polyethylene glycol (PEG), which binds and inactivates CT, enabling the effects of CT to be quantified by comparing control sheep (CT operating) with PEG sheep (CT inactivated). Experiment 1 was conducted indoors, with sheep held in metabolism crates and fed hourly to determine the effects of CT upon apparent digestibility and upon plasma irreversible loss (IRL) rates of methionine, cystine and inorganic sulphate, using 35S labelling. Experiment 2 as a field trial with weaned lambs given a restricted allowance of either lotus corniculatus (CT-containing) or lucerne (non CT-containing), with or without PEG supplementation. In Experiment 1, CT slightly lowered the apparent digestibility of organic matter (0.77 vs 0.80; P<0.1), hemicellulose (0.61 vs 0.67; P=0.118) and markedly reduced nitrogen apparent digestibility (0.72 vs 0.80; P<0.01), but had no effect upon cellulose digestibility. CT increased the IRL of plasma cystine (13.1 vs 7.0 mmol/min; P<0.05) and reduced the IRL of plasma inorganic sulphate (36.8 vs 48.1 mmol/min; P<0.01) but had no effect upon plasma methionine IRL. In Experiment 2, live weight gain and wool growth were similar for sheep grazing lucerne (with and without PEG supplementation) and for sheep grazing lotus with PEG supplementation. In sheep grazing lotus, action of CT increased wool production (12.1 vs 10.9 g/d; P<0.05) and slightly increased live weight gain (203 vs 188 g/d; P=0.07). These experiments showed that CT in Lotus corniculatus increased the amount of cystine available for body synthetic reactions and increased wool growth.

Effects of herbage allowance and a high protein supplement on performance of dairy cows grazing on autumn-winter pastures - Suksombat W; Holmes CW; Wilson GF (Proceedings of the New Zealand Society of Animal Production, 1994)
Two experiments were conducted to assess aspects of the feeding value of winter pasture for lactating dairy cows. During May 1989, three groups of 10 Friesian cows were offered daily herbage allowances of 43 (High, H), 20 (Medium, M) and 13 (Low, L) kg dry matter (DM) per cow, for a four week period in early lactation. Daily herbage intakes, assessed by cutting pastures before and after grazing, were 12.4, 9.1 and 7.6 kg DM per cow, respectively. "Covariance adjusted" daily milk yields (15.6, 12.4 and 9.4 litres/cow), milkfat yields (0.64, 0.54 and 0.41 kg/cow) and protein yields (0.50, 0.36 and 0.28 kg/cow) differed significantly (P<0.01) between treatments. Responses/kg extra herbage DM eaten were 1.0 and 1.9 litres, 31 and 84 g milkfat and 43 and 52 g protein for the H-M and M-L increments, respectively. Apparent liveweight gains and proportion of cows showing oestrus were also positively related to allowance. During June 1990, two groups of 15 Friesian cows in early lactation were transferred from a herbage and grass silage ration to a high herbage allowance of 63 kg DM/cow daily. The yields of milksolids and especially protein immediately increased substantially (P<0.01); the protein concentration increasing from 3.02 to 3.70%. For a period of two weeks, the cows in one of the groups (Treatment) also consumed 2.7kg DM daily of a high protein concentrate supplement (Brewers' grain and soyabean products). Daily milk yields (Control 20.3, Supplemented 22.5 litres), milkfat yields (C 0.87, S 0.94 kg) and protein yields (C 0.75, S 0.82 kg) were increased significantly (P<0.05) by the supplement. Herbage intakes were measured and substitution rates of 0.71 and 0.45 kg pasture DM/kg concentrate DM were estimated using two alternative techniques. The combined results indicate that the nutritive value for milk production of winter pasture is relatively high, provided that a high daily allowance is offered from pastures with more than 2,000 kg DM/ha pre-grazing mass. However, the relatively large increase in milk production caused by the concentrate supplement suggests that aspects of its nutritive value may constrain high levels of milk production where allowance is high.

Effects of milking frequency and machine stripping on milk yields of Dorset ewes - Brief Communication - Knight TW; Gosling LS (Proceedings of the New Zealand Society of Animal Production, 1994)
No astract supplied

Effects of once daily milking in late lactation on cows with either low or high initial somatic cell counts - Kamote HI; Holmes CW; MacKenzie DDS; Holdaway RJ; Wickham BW (Proceedings of the New Zealand Society of Animal Production, 1994)
The present study was carried out in order to measure the effects of once daily milking on somatic cell count (SCC) of cows which had either low SCS or high SCC at the start of the experiment in late lactation. Thirty six cows were used, 18 with low SCC and 18 with higher SCC. Nine cows from each group were randomly allocated to once or twice daily milking for the four week experimental period in March. The yields of milk, fat, protein and lactose were significantly reduced by once daily milking (P<0.01) in both groups. However, the effects of once daily milking on yields was larger for high SCC cows (interaction P<0.01). Once daily milking significantly increased the concentration of protein (P<0.001) in both groups and fat (P<0.01) in only the low SCC group. Once daily milking significantly reduced the concentration of lactose, the effect being larger in the high SCC group (interaction P<0.001). SCC (per ml) was increased by once daily milking, but the effect was significant only in the high SCC group (interaction P<0.10). The total number of cells produced per day were not affected by once daily milking. These results show that SCC can be used with confidence to identify subclinically infected cows in later lactation milked once or twice a day. The results also show that cows with a low incidence of subclinical mastitis can be milked once daily in later lactation, with much less effect on yield of milk and its constituents than would be expected in cows with a higher incidence of infection.

Effects of pre-lamb and conventional full-wool shearing on the productivity of ewes - Dabiri N; Parker WJ; Morris ST; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
The effects of pre-lamb and conventional (post-weaning) annual shearing of ewes on their productivity and that of their lambs were studies over a three year period. Ewes (n-500) were selected from a flock of 5000 mixed-age Border Leicester x Romney ewes at Massey University's Riverside property in the Wairarapa in April 1989 and randomly allocated to two equal sized groups. Both groups were managed under the same conditions until December 1991. Throughout the trial, one group was shorn after weaning in November/December and the second group was shorn prior to lambing in August. Ewe liveweight and lambing performance were measured over three years, and individual ewe fleeceweights were recorded over two full years. Pre-lambing ewe liveweights were similar for both policies in all years, while post-weaning liveweights were greater in pre-lamb shorn ewes in 1989 only. Annual fleeceweights were significantly (P<0.05) greater for the pre-lamb shorn ewes in 1990 (4.07±0.05 vs 3.64±0.06 kg) but not in 1991 (3.61±0.08 vs 3.75±0.09 kg). Lamb birthweights and weaning weights did not differ between shearing treatments. The small difference in ewe and lamb performance between the shearing treatments suggests that management factors, such as the provision of feed and shelter post-shearing, the spread of seasonal work, net income per ewe and cashflow, should determine whether a pre-lamb shearing policy is adopted.

The effects of restricted suckling and prepartum nutritional level on reproductive performance of primiparous crossbred beef cows. - De Nava Silva GT; Burnham DL; McDonald MF; Morris ST (Proceedings of the New Zealand Society of Animal Production, 1994)
Reproductive performance was recorded in a total of 21 two-year-old Hereford x Friesian and Simmental x Friesian primiparous cows before and after restriction of calf suckling. Cows were allocated one of two pastures allowances from day 112 to 212 of gestation so that the high nutrition (HN) group gained 0.75 kg/d, and the low nutrition (LN) group gained 0.17 kg/d during mid-gestation. Suckling was suppressed for 7 days by fitting nose plates to 46-day-old calves in the restricted suckling (RS) group, whereas the normal suckling (NS) group remained as a control. Dominant follicles in the ovaries occurred in all cows by day 32 post partum and underwent a pattern of growth and atresia before first ovulation. Restricted suckling cows had a shorter interval from calving to conception than NS cows (76.0 ± 5 vs 94.1 ± 6 days, P<0.05, whereas genotype and nutritional treatment had no effect on interval to conception. However, the beneficial effect of suckling restriction on days from calving to conception only occurred in cows fed the high herbage allowance in mid-gestation. RS calves spent more time grazing during the period of attachment of nose plates and differences in behaviour remained over a further 5 days after nose plates were removed (62.4 ± 7 vs 38.6 ± 7 minutes spent grazing; P<0.001), but were lighter at weaning (146.7 ± 3 vs 162.4 ± 3 kg; P<0.01). Despite the lower calf liveweight at weaning it is concluded that manipulation of suckling through fitting nose plates to calves can be used to initiate earlier re-breeding in primiparous cows.

The effects of season on placental development and fetal growth in sheep - Jenkinson CMC; Peterson SW; MacKenzie DDS; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
Autumn-born lambs have been reported to have lower birth weights than spring-born lambs by 0.4 to 1.0 kg, but the physiological basis of this difference is unknown. This study examined the effects of season on fetal growth and placental development independent of the confounding effects of maternal nutrition. Romney ewes (aged 5 and 6 years) were randomly allocated to groups mated in December (n=13) or March (n=13 with a similar live weight at mating (55.6±1.8 vs 55.7±1.9 kg, mean±SE, P>0.10) and managed for a similar live weight at day 140 of gestation (62.5±1.8 vs 62.9±1.9 kg, P>0.10). At day 140 of gestation, measures of fetal growth and placental development, adjusted for litter size, were (December- vs March-mated): individual fetal weight (4.15±0.16 vs 5.07±0.16 kg, P<0.001); total fetal weight per ewe (6.42±0.18 vs 7.14±0.22 kg, P<0.01); caruncle number (114.5±4.1 vs 121.0±4.2, P>0.10); placentome number (89.4±4.2 vs 106.9±4.3, P<0.01); caruncle occupancy, i.e. number of placentomes/number of caruncles (0.79±0.03 vs 0.88±0.03, P<0.05); and total placentome weight (564.7±34.0 vs 679.0±34.9 g, P<0.05). These results suggest that seasonal differences in birth weight of lambs are mediated not by differences in maternal nutrition but rather by a direct seasonal effect on placental size (specifically the formation of placentomes and hence total placental weight).

Evidence for a diffusible factor influencing the switching of ovine and bovine milk gene expression leads to identification of factors - Molenaar AJ; Musgrave DR; Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Our earlier in situ hybridisation studies have shown heterogeneous expression of milk protein genes. At some sites, a sharp demarcation of mRNA expression is seen at the basement membrane between 'active' and 'inactive' tissue, while at other nearby sites, a reciprocal gradient of mRNA expression about 10 cells wide is seen. The alveoli in these latter 'inactive' sites contain leucocytes which indicates that they have been 'inactive' longer than the former. This suggests a factor could be diffusing between 'inactive' and 'active' tissues and influencing milk gene expression. We used a consensus oligomer corresponding to the linkers between the fingers of zinc finger DNA binding proteins in a polymerase chain reaction performed on cDNA from 'active' versus 'inactive' mammary mRNA. Differences and similarities were observed in the sizes of the DNA products from each sample. Several of the bands present in the 'active' cDNA and absent from the 'inactive' cDNA were cloned and some were found to have homologies to zinc finger and other DNA binding proteins. It is possible that we have partially isolated a component of the pathway that maintains lactation.

Farm management implications of a seasonal price differential for factory supply milk production - Gray DI; Yuretich PA; Lynch GA (Proceedings of the New Zealand Society of Animal Production, 1994)
A number of New Zealand dairy companies have proposed a differential pricing scheme that would discount the price paid for "peak milk" and provide a premium for milk supplied "off peak". A linear programming model was developed to analyse the on-farm impact of a differential milk pricing scheme. The differential pricing scheme used in the study was based on a dairy company where farmers supplied 30% of total milk during the October/November peak and 70% during the off-peak period (peak-to-shoulder ratio of 30:70). The impact of three price differentials of $0.82/kg MS, $1.63/kg MS and $2.45/kg MS between peak and off-peak milk was analysed. The results showed that if the case study farmer made no management changes to his system, there would be little change in the farm gross margin per hectare under a differential pricing scheme, provided the farm had a peak-to-shoulder ratio close to that used by the dairy company to set the price differential. However, returns declined by $182/ha, if the farm peak-to-shoulder ratio was 40:60 and increased by $185/ha if the ratio was 20:80. A price differential of at least $1.71/kg milksolids ($3.00/kg MF) between peak and shoulder milk, was required to reduce peak milk production significantly. As the price differential increased, the LP model selected solutions that reduced both total milk production and the ratio of peak-to-shoulder milk. Management changes selected to modify the pattern of milk production included; a reduction in stocking rate, a shift to an earlier calving date (and then a split calving), an increased lactation length, higher cow condition at calving and greater use of supplements.

Farm management research in New Zealand and its contribution to animal production - Parker WJ; Gray DI; Lockhart JC; Townsley RJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Farm management is concerned with procedures that assist farm managers allocate limited physical, financial and human resources to achieve their personal (and family) objectives. The process of resource allocation usually occurs with imperfect knowledge, and in the context of a biological and socio-economic system over which the farm manager has incomplete control. Management functions of planning, implementation and control are used to assist decision-making and the realisation of objectives in this uncertain environment. These occur at strategic, tactical and operational levels. Early development of the farm management discipline was strongly shaped by microeconomic theory (especially production economics) and quantitative methods of analysis (mainly from operations research). More recent development of the discipline has seen the addition of the farming systems research (FSR) philosophy and the application of qualitative techniques used in the social sciences. These additions have improved the capacity of farm management research to account for the needs and aspirations of the farmer and farm family, and to consider the dynamics of the community in which they live. This holistic view recognises that farmers frequently do not exhibit economic optimising behaviour and that their decision-making processes often ignore the classical steps outlined in management textbooks. In contrast, animal scientists use a reductionist approach to investigate the animal component of the farming system, independent of the financial, social, and sometimes physical, constraints of a commercial farming situation. It is logical then that farm management specialists should work with animal scientists to interpret animal-related research within the context of farming systems. Today's increasingly sophisticated market for land-based products demands effective partnerships among all participants in the science - technology - production - processing - marketing chain. Issues such as sustainability, product quality, animal welfare and the development of effective information systems are not the preserve of any single discipline. The challenge to farm management researchers and animal scientists is to continue to develop effective working relationships in the future.

Genetic and phenotypic parameters associated with lean tissue growth in Dorset Down sheep - Nsoso SJ; Young MJ; Beatson PR; Bell ST (Proceedings of the New Zealand Society of Animal Production, 1994)
Genetic and phenotypic parameter estimates were derived from performance data collected over nine years for the Lincoln University Dorset Down flock. Data were for animals born each spring and run at pasture. Ewes (n=922) were measured in autumn and rams (n=819) in winter. Measurements were live weight and in vivo fat and muscle depths. Genetic and phenotypic parameters were estimated using multi-variate AIREML analyses by fitting an individual animal model with animal as a random effect, birth rank, age of dam and year of birth as fixed effects and age at measurement as a covariate. Multi-variate heritability estimates (± s.e.) for live weight, fat and muscle depths were 0.42 (±0.04), and 0.30(±0.05) for rams and 0.26(±0.01), 0.20(±0.05) and 0.13(±0.03) for ewes respectively. Estimates of genetic correlations were generally moderate to high for the two sexes. The genetic correlation between live weight and fat depth was significantly different for the two sexes, with rams (0.42±0.10) having a higher value than ewes (0.24±0.02). Phenotypic correlations differed between the sexes, with estimates for ewes being slightly higher. For both sexes, parameter estimates were different from those used to derive the indices used to select for lean tissue growth, ram estimates being consistently higher while those for ewes were more equivocal.

Growth rates, wool production and health of Awassi and Texel crossbred ram lambs - Knight TW; Thomson NA; Power MJ; Gallen J (Proceedings of the New Zealand Society of Animal Production, 1994)
Birth and weaning weights, liveweight gain, wool weights and characteristics, and animal health were recorded on 214 ram lambs consisting of about equal numbers of Awassi and Texel cross Romney, Coopworth and Dorset ram lambs. Changes in blood GGT concentrations were also measured in Awassi x Coopworth and Romney ram lambs following dosing with sporidesmin. Pre- and post-weaning growth rates of Awassi crossbreds were lower (P<0.001) than Texel crossbreds. Awassi crossbreds had a higher incidence of footscald and higher (P<0.05) strongyloid egg counts in their faeces in May. After dosing with sporidesmin blood GGT concentrations were higher (P<0.001) in Awassi x Coopworth than Romney ram lambs. Awassi crossbreds had lower (P<0.001) fleece weights and wool quality than Texel crossbreds.

Growth-promoting and metabolic actions of recombinant ovine placental lactogen and bovine growth hormone in young lambs - Min SH; MacKenzie DDS; Breier BH; McCutcheon SN; Gluckman PD (Proceedings of the New Zealand Society of Animal Production, 1994)
It has been shown previously that ovine placental lactogen (oPL) has a growth-promoting effect in the growth hormone (GH)-deficient dwarf rat. However, this effect has not been verified in an homologous system using animals with an intact somatotrophic axis. To examine the effects of oPL in the sheep, we injected lambs with recombinant oPL (0.1 mg/kg liveweight/day, n=16) or saline (n=16) for 21 days commencing on day 3 of life and compared their effects on body growth and energy intake with those in lambs treated with the same dose of recombinant bovine growth hormone (bGH, n=16). Circulating concentrations (ng/ml) of hormones in saline- vs bGH- vs oPL- treated lambs at day 20 of treatment were (mean±SE): oPL, <0.5 vs <0.5 vs 12.8±0.5; GH, 10.8±5.0 vs 48.4±5.0 vs 12.6±5.0, P<0.001; insulin-like growth factor-I (IGF-1), 267.6±14.4 vs 302.4±14.2 vs 291.7±14.4. Average daily gain (kg/day) during treatment was significantly (P<0.05) greater in oPL-treated lambs (0.28±0.01) than in saline-treated (0.25±0.01) or bGH-treated (0.24±0.01) lambs. Similarly, there were significant (P<0.05) increases in total energy intake (over the 21 day treatment period) during treatment with oPL (112.5±3.5 MJ ME), compared with bGH (102.0±3.5 MJ ME) or saline (102.0±3.5 MJ ME) treatment. It is concluded that oPL is somatogenic in young lambs. This effect may be mediated by stimulating voluntary feed intake rather than by elevating circulating concentrations of IGF-I.

Hepatic protein variation among Romneys selected for resistance or susceptibility to sporidesmin-induced liver damage. A quantitative two-dimensional polyacrylamide gel electrophoresis study - Lu YF; Morris CA; Towers NR; Jordan TW (Proceedings of the New Zealand Society of Animal Production, 1994)
Quantitative two-dimensional polyacrylamide gel electrophoresis has been used to search for variation among liver proteins in flocks of sheep which had been selected for either resistance or susceptibility to sporidesmin- induced liver damage. The goal was identification of proteins whose DNA sequences might be used to select animals for resistance to facial eczema. The quantitative gel techniques were used because of their ability to detect variability among many proteins in a single tissue sample. Differences in relative proportion were tested for 62 proteins among 5 ewes from each of the resistant and susceptible flocks. There were 7 proteins which showed statistically significant differences (P<0.05) between the flocks. When an analysis was made of changes in the relative proportions of proteins 2 days after experimental challenge of resistant flock ewes (n=8) with sporidesmin, 0.13 mg per kg body weight, 25 of 79 liver proteins showed significant change (P<0.05). This included partial loss of a 25 kDa, pI 5.7, protein which was also three times more abundant in undosed susceptible than undosed resistant females. These results are discussed in terms of the possible relationships between protein variation and the magnitude of toxic tissue damage.

Herbage intake, ingestive behaviour and diet selection in sheep grazing Holcus lanatus and perennial ryegrass swards - Montossi FM; Hu Y; Hodgson J; Morris ST (Proceedings of the New Zealand Society of Animal Production, 1994)
Grazing behaviour, diet selection, and herbage intake of ewes in mid- pregnancy were studied on perennial ryegrass/white clover and Holcus lanatus/white clover swards rotationally grazed at medium and high allowances (6% and 12% of liveweight as herbage dry matter respectively) during late autumn. Estimates of herbage mass and sward height before grazing were similar for the two pasture types. Animals on both pasture types concentrated grass rather than clover in the diet, and extrusa samples from both showed evidence of limited concentrations of condensed tannins. Herbage intake was 28% higher from ryegrass than from Yorkshire fog swards (1410 vs 1100 ± 29 g DM/day) and 19% greater at high allowance (1370 vs 1150 ± 50 g OM/day). Bite weight was 61% greater for Yorkshire fog than for ryegrass (139 vs 86 ± 7.0 g OM/bite) and 30% lower for medium allowance than for high allowance (90 vs 130 ± 7.0 mg OM/bite). Grazing time was higher on ryegrass swards and for medium allowance (610 vs 500 ± 34 mins and 620 vs 495 ± 27 mins) whereas differences in rate of biting were small. There was a small advantage in the organic matter digestibility of the herbage selected in favour of ryegrass swards (85.7 vs 82.2 ± 0.3%), while no differences were found between herbage allowances. It is concluded that herbage intake was influenced more by nutritional than by behavioural constraints, but that these effects need to be investigated in animals of higher production potential and nutrient demand.

Hormonal and ovarian responses in Romney ewe hoggets after synchronisation and superovulation treatment. - Campbell JW; McDonald MF; Wickham GA (Proceedings of the New Zealand Society of Animal Production, 1994)
Twelve, 10-month old ewe hoggets (Av LW 32.5 kg) were placed in metabolism crates under controlled lighting (11 h L:13 h D) for a 9 d adaptation period and were fed for maintenance. They were synchronized by vaginal insertion of CIDR and treated with gonadotrophins for superovulation. Of the 12 hoggets 9 had two or more successive plasma samples with > 0.9 ng/ml progesterone (P4) indicating they had ovarian activity prior to treatment. Mean P4 concentrations prior to treatment (d - 3) were 0.69 ± 0.18 ng/ml and had risen to 1.50 (± 0.38), 1.72 (±0.35), 1.36 (±0.11) and 1.31 (±0.10) ng/ml for d 0 to d 3 of treatment. On d 9, 10 and 11, prior to CIDR removal, P4 levels were back to base line levels (0.60, 0.46 and 0.57 (±0.06) ng/ml respectively). The mean number of follicles and corpora lutea were 5.0 (±0.95) and 1.8 (±0.53), respectively. Total CL had a negative correlation (r = -0.64, P<0.05) with the P4 concentration on the day of CIDR removal. Six of the 12 ewes had an LH peak within 25 hours after CIDR removal. In addition, those ewes treated during late cycle tended (P>0.10) to have a better ovarian response than those treated at early or mid cycle. These results suggest it may be necessary to use two CIDR to maintain a sufficiently long period of P4 elevation. In addition, the day of the cycle that the CIDR is inserted may be important to achieve maximum response from ovulation enhancement treatment in ewe hoggets.

How relevant are current and emerging genetic technologies to the beef breeding cow? - Blair HT; Garrick DJ (Proceedings of the New Zealand Society of Animal Production, 1994)
The genetic merit of stock in the commercial sector of the beef breeding herds is dependent on the rate of genetic gain in nucleus herds and the length of delay it takes to transfer this genetic gain to commercial herds. This paper states the factors controlling the rate of genetic gain and genetic lag and examines the impact of current and future technologies on these factors. The setting of selection objectives and opportunities for crossbreeding in New Zealand beef breeding herds are also mentioned briefly. The maximum theoretical rate of genetic gain in beef cattle herds is about 3.4sigmaT (genetic standard deviations). Current technologies should allow a rate of gain of about 0.25sigmaT but results from New Zealand beef cattle selection experiments suggest that the actual rate achieved in the industry is unlikely to exceed 0.1sigmaT. It is suggested that many new technologies becoming available will either have little impact on the rate of genetic gain or will be too expensive to apply in New Zealand's extensive beef cattle industry. Opportunities will exist for nucleus breeders who are prepared to cooperate with each other giving them a larger pool of breeding cows. The most likely genetic lag using current practices is about 10 years in the New Zealand beef cattle industry. By generating replacement females from only young parents and by accessing sires of above average genetic merit, it should be possible to reduce genetic lag to about 1 year. It is concluded that the New Zealand beef cattle industry could greatly enhance the rate of genetic gain and reduce the level of genetic lag through the application of existing technology. Furthermore, the establishment and application of sound selection objectives is an immediate priority.

In vitro production of cattle embryos: Use in beef twinning programmes. - Pugh PA; Thompson JG; McGowan LT; McMillan WH; Tervit HR (Proceedings of the New Zealand Society of Animal Production, 1994)
This study investigated the survival of in vitro derived embryos as single or twin pregnancies following their twin transfer to recipient cows. Abattoir-derived oocytes were matured, fertilised and then cultured for 6-7 days using our standard laboratory procedures. One hundred and forty good quality late morula and blastocysts were transferred non-surgically, in pairs, to recipient cows on day 7 of the oestrous cycle (day 0 = oestrus). Recipients were monitored by ultrasound for pregnancy up to Day 60 and embryo survival was determined. While 57 (81%) of recipients did not show oestrus by day 21, only 39 (56%) were pregnant on day 35 and 30 (77%) of the pregnancies were twins (embryo survival; 57%). Increasing stage of gestation was associated with a decrease in pregnancy rate, twin pregnancies and embryo survival (46%, 37% and 31%, respectively) on day 60. The results show that while high initial pregnancy rates can be established following the transfer of two in vitro derived embryos, embryo survival drops during early pregnancy. Current research efforts are investigating factors that may influence early embryo survival in cattle.

Increasing per cow milk solids production in a pasture-based dairy system by manipulating the diet: A review. - Edwards NJ; Parker WJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Research suggests that the genetic potential for milksolids (MS) production by New Zealand dairy cows is considerably under-exploited under current grazing conditions. There is also a growing awareness that only small improvements in MS production per cow can be achieved with pasture-only systems on high producing New Zealand dairy farms (i.e. those producing 315kg MS/cow or 1,000kg MS/ha). The review identifies nutritional limitations of a pasture-based diet as one of the barriers to further increases in per cow MS production. It is argued that further increases in per cow production on New Zealand's high producing (in terms of per cow MS production) dairy farms is contingent upon the need to balance the pasture- based diet for protein, carbohydrates, fibre, minerals and vitamins through strategic use of feedstuffs. One of the keys to successfully balancing a pasture-based diet is to obtain better data on the nutritional status of pasture throughout the year so that the most economic feedstuffs which will balance the ration can be identified.

Influence of insulin-like growth factor-1 (IGF-1) on components of the haematopoietic and lymphatic systems - Kuhn Sherlock B; Morel PCH; Mathis JM; Blair HT; McCutcheon SN; Marbrook J; Breier BH; Gluckman PD (Proceedings of the New Zealand Society of Animal Production, 1994)
Increased thymic weights have been reported in sheep selected for resistance to internal parasites and treatment with IGF-1 increases thymic and splenic weights in sheep, suggesting that IGF-1 may have a role in regulating immune function. This hypothesis was examined in four experiments using mice as a model. Expt 1 Unselected Swiss mice (n-24) were injected 2 x daily with 30 mg/d rhIGF-1 or saline for 26 days from 28 days of age. IGF-1 treatment increased spleen weight at a common body weight (118.2 vs 95.9, pooled standard error (PSE) = 6.2 mg, P<0.05), but did not affect thymic regression (thymic weights at the end of treatment: 85.5 vs 81.9, PSE = 4.0 mg). Expt 2 Unselected female Swiss mice (n=22, age = 84.8±0.8 days) were injected 3 x daily with 30 mg/d rhIGF-1 or saline for 17 days. IGF-1 treatment increased thymic weight at a common body weight (78.4 vs 58.0, PSE = 3.0 mg, P<0.01), but had little effect on splenic weight (180.1 vs 163.0, PSE = 7.5 mg, P>0.10), Expt 3 Histological sections of spleens from High (H), Control (C), and Low (L) IGF-1 selected mice at 30 (n=30) and 120 (n=35) days of age were analyzed for the density of megakaryocytes (precursor cells for thrombocytes), and the percentage of the area covered by white pulp (lymphatic tissue). L mice had, compared to C and H mice, lighter spleens (62.6 vs 76.8 vs 89.6, PSE = 5.3 mg, at 30d; 60.2 vs 109.5 vs 114.5, PSE = 7.4 mg, at 120d; P<0.05), and a lower density of megakaryocytes (9.2 vs 13.4 vs 14.7, PSE = 1.6 n/mm2, at 30d; 2.1 vs 13.9 vs 14.3, PSE = 2.0 n/mm2, at 120d; P<0.05), but were not different in the percentage of the area covered by white pulp (16.1 vs 14.1 vs 13.4, PSE = 1.3%, at 30d; 28.3 vs 23.1 vs 23.8, PSE = 2.4%, at 120d). Expt 4 Mice from the three IGF-1 selection lines (n=13 vs n=13 vs n=14 for L vs C vs H, age=86.8±2.3 days) showed no difference in spleen weights (110.8 vs 137.4 vs 139.0, PSE = 11.8 mg; P>0.10). In response to an antigenic challenge with sheep red blood cells (SRBC), there was a small effect (P=0.10) of selection line on the number of plaque-forming (immunoglobulin M (IgM)- producing) cells (PFC) per spleen (880x103 vs 954x103 vs 1187x103, PSE = 130x103), but the differences in anti-SRBC antibody titres (IgM) in the plasma (10.8 vs 11.1 vs 11.7, PSE = 0.6) were not significant. It is concluded that IGF-1 affects splenic and thymic weights independently, that it influences the density of megakaryocytes in the spleen, and that it has an effect on the number of PFC per spleen in response to a SRBC challenge. However, the biological significance of these effects is still to be established.

Isolation of cDNA subclones encoding ovine glucose transporter proteins - Brief Communication - Bennett BL; Grigor MR; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 1994)
No abstract supplied

Issues of sustainability in animal production and the implications for science: An international perspective. - Parry A (Proceedings of the New Zealand Society of Animal Production, 1994)
Issues of sustainability in animal production in developed countries involve a trend away from intensive production systems and destruction of the environment, towards improved animal welfare and increased product quality, with an emphasis on reduced use of chemicals in production systems. The negative environmental impact and the loss of biodiversity, due to livestock production systems, are major issues in both developed and developing countries. In developing countries, desertification and deforestation, the sustainable management of wildlife systems and the need to reduce competition between humans and animals for scarce resources, are all major issues of sustainability. While the developed world is looking towards "de-intensifying" its animal agriculture, the developing regions of the world have a perceived need to intensify animal production systems in order to support increasing populations, urban growth and an increased demand for animal products. The implications for scientific research include: aiming to optimise rather than maximise production; greater emphasis on the ecological aspects of sustainable systems, maintenance of biodiversity and natural resources; and minimising external inputs and satisfying the food, income and social needs of rural communities. Scientific communities must increasingly seek international collaboration in a global approach to the challenge of sustainable animal production.

Lamb weight gain and faecal egg count when grazing one of seven herbages and dosed with larvae for six weeks - Niezen JH; Waghorn TS; Raufaut K; Robertson HA; McFarlane RG (Proceedings of the New Zealand Society of Animal Production, 1994)
One hundred and forty Polled Dorset lambs were randomly allocated to graze one of seven herbages (n = 20/herbage) and either trickle dosed (n=12) with a total of 108,000 third stage gastrointestinal nematode larvae (50% Trichostrongylus colubriformis and 50% Ostertagia circumcincta) over 6 weeks, or undosed (n=8) and allowed to ingest any nematode larvae on pasture. After 28 days on the trial lambs dosed with larvae had higher (P<0.001) faecal egg counts (FEC's) than undosed lambs but after 42 days egg counts did not differ (P>0.05) between dosed and undosed groups. Dosing with larvae did not significantly alter the liveweight gain (LWG). Herbage species affected LWG, being highest on lotus (Lotus pedunculatus cv Maku) and lowest on ryegrass/white clover (Lolium perenne/Trifolium repens), with other treatments being intermediate. Dosed lambs grazing chicory (Chicorium intybus) had more faecal dags than any other group of lambs. Those grazing G27 red clover (Trifolium pratense) were worst afflicted by a dermatitis type condition commonly referred to as trefoil dermatitis. Plasma pepsinogen levels differed significantly (P<0.05) only between dosed and undosed groups grazing pawera red clover, ryegrass/white clover and sulla (Hedysarium coronarium). Worm counts were undertaken on ryegrass/white clover and sulla grazed lambs. Both dosed and undosed groups grazing ryegrass/white clover had higher (P<0.05) abomasal worm counts than sulla grazed lambs, intestinal worm counts were highest in dosed lambs grazing ryegrass/white clover, intermediate in the dosed lambs grazing sulla and in undosed lambs grazing ryegrass/white clover, and lowest in the undosed lambs grazing sulla.

Liveweight and fleece production from New Zealand, South African and first cross Angora goats - Newman S-AN; Paterson DJ; Power MT (Proceedings of the New Zealand Society of Animal Production, 1994)
The release of the South African Angora from quarantine will be the single factor with the greatest impacts on the New Zealand mohair industry over the next few years. In order to provide information on production under New Zealand farming conditions, trial was carried out comparing the liveweight and fleece production of South African, New Zealand and first cross South African x New Zealand (Crossbred) Angora goats from birth to two years of age. Crossbred and South African goats were significantly heavier than New Zealand Angoras at most ages. South African Angoras were heavier than Crossbreds for the first 8 months only. Fleeces from South African goats were heaviest, New Zealand Angora fleeces were lightest, while Crossbred fleece weights were intermediate between the parental breeds at all shearing times. Fibre diameter of fleeces from New Zealand goats was finer at 12 months of age (24.8 ± 0.4, 27.0 ± 0.4, 27.6 ± 0.3 µm for New Zealand, Crossbred and South African respectively) but there were no differences at 18 and 24 months of age. Medullation and kemp levels were higher in New Zealand than South African fleeces at all sampling times. Medullation and kemp levels in the Crossbred fleeces were higher than the mean of the parent levels, indicating heterosis effects. Medullation levels did not differ in Crossbred and New Zealand fleeces at 18 and 24 months of age. Advantages of the South African Angora over the New Zealand Angora goat were confirmed in this study, however anticipated improvements in fleece quality were not achieved in the first cross.

Making use of technology diffusion - Parminter TG; Parminter IA (Proceedings of the New Zealand Society of Animal Production, 1994)
Diffusion is the process by which the adoption of new technologies spreads over time throughout the members of a social system. Many science institutions target their extension efforts at adoption leaders in a population, and rely upon a trickle down of the technology to spread it to the general population. Diffusion is described as resulting from the effects of farmer characteristics, technology characteristics, farming systems, and communication networks available for diffusion. The process of diffusion is enhanced by extension activities, and much can be done by scientists to improve the value of their technology to intended recipients. In order to do this, farmers should be involved during the development of technologies to identify the characteristics most important to them and their farming systems. New technologies should be evaluated for their effects upon the whole farm system and upon farmer perception. Sufficient information is needed by potential adopters for them to successfully implement new technology. The information they value most is provided by other farmers with scientific support for the essential principles they should apply.

Mammary involution in ewes: Changes in milk plasminogen and plasmin - MacKenzie DDS; Cottam YH; Knutson RJ; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
Multiparous Border Leicester x Romney ewes were weaned early (day 35 of lactation), milked to empty the mammary gland and again milked 18 h later (day 0 of experiment) to establish baseline milk yields and concentrations in milk of the proteolytic enzyme plasmin and its zymogen plasminogen. They were then divided into 3 groups to be milked 3 (n=5), 8 (n=6) or 15 (n=5) days after the day 0 milking to determine changes in concentrations and yields of plasmin and plasminogen in mammary gland secretions during involution. Yields (mean±SE) on days 0 (groups 1 + 2 + 3), 3 (group 1), 8 (group 2) and 15 (group 3) were: secretion (g), 785±31.2 v. 598±94.8 v. 478±86.8 v. 51±66.6; plasminogen (mg), 7.8±2.2 v. 78.7±11.1 v. 22.4±4.6 v. 3.9±2.1; and plasmin (ug), 11.5±2.38 v. 148.5±8.00 v. 51.6±7.92 v. 4.9±2.32. Corresponding concentrations in the secretions were (ug/ml): plasminogen, 0.01±0.002 v. 0.15±0.027 v. 0.046±0.005 v. 0.061±0.007; and plasmin, 0.015±0.006 v. 0.275±0.027 v. 0.118±0.011 v. 0.083±0.009. There was a linear decline in the volume of secretions from day 0 to day 15. In contrast there was a transient increase (15 fold) in plasminogen and plasmin yields by 3 days after milking. These data suggest that any role of plasmin in mammary gland involution is likely to be limited to the first week after early weaning.

Managing the high performance beef cow herd - where to next? - Lowe KI (Proceedings of the New Zealand Society of Animal Production, 1994)
Historically, the breeding cow has established its place on New Zealand sheep and beef farms as a 'hardy' animal, able to withstand the vagaries of climate and feed supply, and for 'cleaning-up' rough pastures generally assisting output from the ewe flock - the main enterprise. The cow has been particularly useful where contour or cost prevented cropping or conservation. In this context, pure breeds such as Angus or Hereford have served well. The traditional role of the beef cow needs to be reviewed as farmers: - move to cross-breeding and use more 'productive' breeds - have much higher expectations of beef income relative to sheep - increase their proportion of beef to sheep - develop their properties Data from the 'Limestone Downs' property near Port Waikato is presented to show that this 'new' cow in the 'new' environment presents challenges and opportunities not earlier foreseen. At Limestone Downs, three-way cross- breeding of the Angus herd started in 1984, with Hereford and Friesian bulls introduced. At that time, average calf weaning weight was 180 kg. In 1992 the last of the pure Angus cows weaned calves of 205 kg, with the 3-way cross cows weaning calves at 250 kg. Mean cow liveweight of about 420 kg has not changed since 1984. However, the liveweight of the cross-bred cows drops 34- 40 kg between calving and weaning, whereas the Angus tended to stay constant. Additional calf weaning weight has cost the cow liveweight which must be replaced before the following spring. With increased subdivision, pasture development and greater cattle numbers there is no longer the rough feed for cows to 'survive' on. This, coupled with a cow now bred to produce a heavy calf at weaning at the expense of her own body condition if necessary, can lead to re-breeding problems and high cow losses. What of the future? We need to be clear about our expectations of the breeding cow, and perhaps accept that in the traditional role, the traditional cow needs only minor modifications. At the other end of the spectrum however, in a situation where the cow is a direct competitor for feed, we need to consider a whole spectrum of options such as twinning, as these are developed and proven.

Measurement of steroids by enzymeimmunoassay: An environmentally friendly alternative to radioimmunoassay - Henderson KM; Hardie AHM; Camberis M (Proceedings of the New Zealand Society of Animal Production, 1994)
Enzymeimmunoassays (EIAs) for oestradiol-17b and progesterone were developed using antibody-coated microtitre plates, and steroid-horseradish peroxidase conjugates as steroid 'tracers'. The characteristics of standard curves and the precision of measurements were comparable between the EIAs and corresponding radioimmunoassays (RIAs). The applicability of the EIAs was demonstrated by using them to measure oestradiol-17b and progesterone concentrations in media sampled daily from cultures of bovine granulosa cells. The EIAs detected the characteristic switch in cellular steroidogenic capacity from oestradiol-17b to progesterone production typical of cultured granulosa cells. There was a significant linear correlation (P<0.001) between the EIAs and RIAs in the concentrations of steroids measured in granulosa cell culture medium by the two immunoassay formats. These findings may encourage other laboratories to consider converting "in-house" RIAs to EIAs, thereby eliminating the potential health and environmental hazards associated with the radioisotopes required for RIA.

Mouse mammary fat pad interacts with mitogens to stimulate epithelial growth in vitro - Hovey RC; McFadden TB; MacKenzie DDS (Proceedings of the New Zealand Society of Animal Production, 1994)
Issues of sustainability in animal production in developed countries involve a trend away from intensive production systems and destruction of the environment, towards improved animal welfare and increased product quality, with an emphasis on reduced use of chemicals in production systems. The negative environmental impact and the loss of biodiversity, due to livestock production systems, are major issues in both developed and developing countries. In developing countries, desertification and deforestation, the sustainable management of wildlife systems and the need to reduce competition between humans and animals for scarce resources, are all major issues of sustainability. While the developed world is looking towards "de-intensifying" its animal agriculture, the developing regions of the world have a perceived need to intensify animal production systems in order to support increasing populations, urban growth and an increased demand for animal products. The implications for scientific research include: aiming to optimise rather than maximise production; greater emphasis on the ecological aspects of sustainable systems, maintenance of biodiversity and natural resources; and minimising external inputs and satisfying the food, income and social needs of rural communities. Scientific communities must increasingly seek international collaboration in a global approach to the challenge of sustainable animal production.

The New Zealand policy framework for sustainable agriculture and some implications for animal production research - Frizelle JA; Morris SD; Walker AB (Proceedings of the New Zealand Society of Animal Production, 1994)
International environmental influences are becoming increasingly important to farm management decisions on New Zealand farms. New Zealand has been active in meeting international commitments in issues such as the UNCED Biodiversity Convention, the UN Framework Convention on Climate Change, and the Montreal Protocol on Ozone Depletion. New Zealand now needs to focus on the impacts of agriculture on the environment. This paper backgrounds recent policy developments in New Zealand leading up to the release of a Ministry or Agriculture and Fisheries position paper on sustainable agriculture. The position paper defines sustainable agriculture as having environmental, economic, social and market dimensions. MAF believes that new approaches will be needed to encourage farmers to adopt more sustainable farming systems. There are market opportunities presented by providing customers with assurances of the environmental quality of our products and the processes by which they are produced. There are also issues of resource degradation that must be addressed through standards under the Resource Management Act. The influence of these changes on farming practices in New Zealand is reviewed in this paper. Issues confronting farming systems researchers and animal production scientists wishing to contribute to sustainable agriculture in New Zealand are identified.

Nutritional buffering: Do we make the best use of this phenomena in the breeding cow - Pleasants AB; Barton RA; McCall DG (Proceedings of the New Zealand Society of Animal Production, 1994)
The nutritional buffering capacity of the beef cow, defined as the ability to absorb low levels of feeding without compromising productivity, is reviewed in regard to winter management. It is shown that resistance to liveweight loss is repeatable for cows within the same herd between years (correlations 0.4 to 0.8, P<0.01). However this capacity is associated with lower calf weaning weight (correlations 0.3 to 0.5, P<0.05). There was no association between the amount of winter liveweight loss and cow liveweight, calf birth weight or time to first oestrus in the cow. It is shown that these results are consistent with evidence for the variation of maintenance requirements between cows. It is suggested that the buffering capacity of the beef cow could be exploited through animal breeding or by management of early nutrition. There may be no one cow type which is optimal for all farming situations, and instead a range of cow types which are more or less able to buffer feed shortages may be preferred.

The on-farm impact of beef production technologies - Brazendale R; Reid J; McRae A (Proceedings of the New Zealand Society of Animal Production, 1994)
Three beef breeding cow technologies (heifer mating, dairy cross cows, and exotic terminal sire bulls) have the potential to increase cattle gross margins by 48% and increase output from the national beef herd significantly. However, on a whole farm basis where the extra feeding levels required to implement these technologies are taken into account individual farm surpluses increase by only 21%. Samples of farmers from the Taihape/Hunterville and coastal Hawkes Bay regions were all aware of the technologies but had chosen not to use the new technologies for rational reasons. The most frequently stated reason was that the technologies were not suitable for harsh farming environments. Other reasons stated by farmers related to the farmer not being able to provide the breeding cow herd the preferential feeding required for these technologies to express their potential.

Physical performance / financial performance... Ne'er the twain shall meet? - Kirton IF; Mackrell KI; Stone JA (Proceedings of the New Zealand Society of Animal Production, 1994)
The historic development of farm reporting systems has meant an overemphasis upon accounting concepts and formats. The compulsion, in New Zealand, of compliance reporting inhibits reports which reflect progress toward farmer and farm objectives and the underlying nature of the production processes. The utilisation of more sophisticated planning tools and the uptake of objective measures of system performance provide an opportunity to rethink and reconstruct farm management report contents and formats. A model report is presented which attempts to harmonise the physical production processes and the financial consequences of these processes. The report undertaken for a winter milk dairy farm; extends the concept of enterprise to separate land, conservation, herd and replacement activities; clarifies input-output relationships within and between these activities; and analyses financial consequences of these relationships. The model provides; a framework for understanding the relationship between production and finance; a framework for developing comparative measures of performance which take account of systems differences which current industry benchmark's ignore; and a basis for meeting the compliance demands all individuals face.

Predicting the influence of high breeding index dairy sires on farm productivity - Clark JM; Holmes CW; Garrick DJ (Proceedings of the New Zealand Society of Animal Production, 1994)
A computer modes was developed to calculate the effect of a sires genetic merit on the yields of fat, protein and milk produced by his daughters, and on their liveweight, feed requirements and achievable stocking rates. Herd statistics, costs and prices were based on average figures for 1992. The effect of a 1 unit increase in sire Breeding Indexes (BI's) for fat, protein and milk and a 1 kg increase in average daughter liveweight on marginal farm profit per hectare were +$0.48, +$0.98, -$0.36 and -$0.49 respectively in the year of the daughters first lactation. That is, in terms of effects on gross margin per hectare, an increase of 1 unit in protein BI (sire) was equivalent to either +2 fat BI (sire), -3 milk BI (sire) or -2 kg in average daughter liveweight. The net effect of a 1 kg increase in average cow liveweight across a whole herd was calculated as being a reduction of approximately $1.30 in marginal profit per hectare. Trends in future yields of milk components were predicted from an on-farm (per cow) and an industry (supply) perspective. These trends were assumed to be solely due to genetic improvement and were based on estimated rates of genetic gain in both New Zealand (NZ) and the United States of America (USA). Based on these estimates, milk supply to the industry could increase between 30-50% in the next 30 years. This would require annual processing capacity increases in the order of 1.2 - 1.5% per year. Over the last 16 years, increases in milk supply due to greater yields per cow (genetics + management) have only been averaging around 0.6% per year. Careful planning may be required by the dairy industry in order to cope with future supply increases.

Prediction of beef carcass yield from selected commercial cuts expressed as a percentage of side weight - Kirton AH; Bass JJ; Hogg BW; Mercer GJK; Duganzich DM; Woods EG (Proceedings of the New Zealand Society of Animal Production, 1994)
Given that almost all beef carcasses intended for export from New Zealand are boned out into cuts in the boning room of export plants, the feasibility was investigated of carrying the identification of individual animals from the point of slaughter through to sides in the boning room and using the weights (percentages) of selected cuts to predict the yield of saleable meat. A Ruakura beef cuts database with information from sides of 1461 bulls, 1097 steers, 320 heifers and 329 cows, all of known breeding, was used to test the accuracy of beef saleable meat yield prediction from the weights of three hindquarter cuts removed at the same time and site in the boning room. The inside round (topside), outside round (silverside) and thick flank expressed as a percentage of side weight were chosen for use alone and in multiple regression to predict the percentage of the carcass available as saleable meat. A model incorporating % inside and % outside and their interactions with sex (bull, steer, heifer and cow) provided useful prediction of % meat yield (R2 0.77, RSD 2.11%) and if hot carcass weight was added to the equation the R2 improved to 0.78 and the RSD was reduced to 2.06%. The sum of the inside and outside expressed as a percentage of side weight gave the same accuracy of prediction of percentage saleable meat yield as when they were treated as separate independent variables. The use of thick flank gave no improvement in prediction. These results should be compared with the present system where sex class, fat class (grade) and hot carcass weight predicted yield with an R2 of 0.60 and an RSD of 2.80% for the same set of data.

Prenatal wool follicle development in Romney, Merino and Merino- Romney cross sheep - Hocking-Edwards JE; Birtles MJ; Harris PM; Parry AL; Paterson E; Wickham GA; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
The prenatal development of wool follicles has been described separately for the Merino and Romney but a comparative study of both breeds and their cross has not been undertaken. This study compared the rate and timing of follicle development in midside skin samples from Romney, Merino and Merino-Romney cross (MxR) foetuses slaughtered at weekly intervals from day 76 to 144 of gestation. The development pattern of total number of follicles per unit area of skin differed between genotypes as indicated by a significant (P<0.001) genotype x gestational age interaction. The total follicle density of each genotype increased from day 76 to day 105 at which time the follicle density of the Romney peaked at 229 follicles/mm2. Total follicle density of the MxR continued to increase to between 420 and 510 follicles/mm2 between day 104 and 122 of gestation and the Merino reached a peak of 1170 follicles/mm2 at day 125 of gestation. The density of immature (i) and mature fibre-bearing (f) primary follicles (P(f+i)) did not differ (P>0.10) between genotypes over time, with each genotype reaching a maximum density of P(f+i) between days 83 and 90 of gestation. Primary follicles (P) began to reach maturity by gestational day 90 in the MxR and by day 97 in the Merino and the Romney (P>0.10). In all genotypes, secondary follicle (S) initiation began at around day 90 with a small proportion starting to form fibres by day 105 of gestation. There was a significant interaction between genotype and gestational age for both the density of S(f+i) (P<0.0001) and the density of S(f) (P<0.01). Specifically, S(f+i) increased to 175 follicles/mm2 in the Romney, 440 follicles/mm2 in the MxR and 900 follicles/mm2 in the Merino at 105, 105 and 125 days gestation respectively, after which S(f+i) density stayed relatively constant up to birth. These results indicate that follicle initiation and fibre formation in different genotypes occurs at similar ages during fetal growth. The high total follicle density in the Merino is due to a high S density which, in turn, is due to S initiation continuing for longer than in either the Romney or MxR. These data provide a model for the identification of certain physiological factors which affect secondary follicle initiation and development.

Prevalence of two inherited disorders in US Holstein cattle - Robinson JL; Shanks RD (Proceedings of the New Zealand Society of Animal Production, 1994)
The deficiency of uridine monophosphate synthase is a disorder of the de novo pathway for pyrimidine nucleotide biosynthesis. Inherited as an autosomal recessive, it results in early embryonic mortality for the homozygous recessive genotype. In the mid-1980's, heterozygotes were estimated at 1 - 2% among US Holstein cattle. The institution of a testing program for carriers and refusal by US artificial insemination companies to accept carriers into their progeny testing programs has eliminated the condition from the top 400 US Holstein bulls. Bovine citrullinaemia is a defect of the urea cycle. Also inherited as an autosomal recessive, it results in early postnatal mortality for the homozygous recessive genotype. In 1990, heterozygotes constituted 0.3% of US Holstein cattle. At present, no known carriers are among the top 400 US Holstein bulls. Carriers for either condition can be detected by convenient and inexpensive DNA based testing. To guard against these conditions reappearing, a modest testing program among prominent US bulls should be continued and importers should insist that imported Holstein germplasm have no evidence of these conditions.

The processing of different staple strength wools - Maddever DC; Scobie D; Bray A (Proceedings of the New Zealand Society of Animal Production, 1994)
Wool from lines of Romney sheep selected for high and low staple strength and a randomly selected control line were processed into worsted yarn for handknitting (ewe hogget fleeces) and semi-worsted yarn for carpets (adult ewe fleeces). Separate lots of wool were created for each line with the fleeces chosen to ensure that the lots had similar mean fibre diameter, staple length and medullation. Hogget wool yarns were knitted into panels and the adult ewe wool yarns were tufted into carpet. In the hogget wool processing trial, increased staple strength was associated with greater mean length after carding and higher combing yields, with small improvements in yarn tenacity and in knitted panel abrasion and pilling test results. The adult ewe wool processing trial also produced a significant difference in length after carding. At high spindle speeds the high strength line performed better in spinning, producing fewer "end-breaks". The trials indicate there are real advantages for worsted and semi-worsted processing and product performance, warranting premiums for high strength wools.

A prolonged change in body composition induced by endocrine manipulation of the neonate - McCutcheon SN; Kadim IT; Wickham GA; Purchas RW (Proceedings of the New Zealand Society of Animal Production, 1994)
The ability of endocrine manipulation of the neonate to effect prolonged changes in body composition was examined. Treatment of lambs with recombinant bovine somatotropin (rbST) at doses of 0.1 or 0.3 mg/kg liveweight/day for 11 weeks from birth elevated circulating ST concentrations (P<0.01) but had no effect on circulating concentrations of insulin-like growth factor-1 or on liveweight gain compared with excipient-treated lambs. However, at 8 months of age (5 months after cessation of treatment), ultrasound backfat depths (Mean±SE) were significantly (P<0.05) higher in lambs previously treated with excipient (3.4±0.3 mm) than in those treated with rbST at 0.1 mg/kg (2.8±0.3 mm) or 0.3 mg/kg (2.5±0.3 mm). In a second study, rats were treated with saline vs. 0.2 ug/g rbST vs. 0.4 ug/g rbST vs. 0.2 ug/g pituitary ovine prolactin (poPRL) vs. 0.4 mu/g poPRL for the first 21 days of life. At 120 days of age they were euthanased, selected fat depots weighed and the carcasses analysed for fat content. Neonatal treatment with rbST or poPRL significantly (P<0.05) reduced weight of the subcutaneous scapular fat depot (1.08±0.18 vs. 0.46±0.17 vs. 0.52±0.18 vs. 0.50±0.17 vs. 0.49±0.17 g) and carcass fat content (5.88±0.27 vs. 5.03±0.26 vs. 4.58±0.27 vs. 5.28±0.26 vs. 4.70±0.26%) but did not influence weights of the subcutaneous abdominal, genital or perirenal fat depots. These results suggest that endocrine manipulation of the neonate may offer a means of producing desirable changes in the composition of production animals while avoiding consumer resistance to the use of hormonal growth promotants close to the time of slaughter.

Reduction of carcass fatness in overfat lambs fed low energy diets supplemented with protein - Liu AH; Young MJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Forty crossbred (Dorset Down x (Border Leicester x Romney)) overfat (ultrasonic GR 13.3 ± 0.5 mm), ewe lambs aged approximately 6 months and weighing 40.4 (±0.8) kg live weight were randomly allocated to either an initial slaughter group or one of three dietary treatment groups on the basis of live weight and ultrasonic GR measurement. Dietary treatments consisted of three pelleted diets that contained 101 g (MP), 189g (HP) and 274g (SP) crude protein with estimated metabolizable energy contents ranging from 7.1 to 7.8 MJ per kg dry matter. Lambs were fed ad libitum for 42 days. Throughout the experiment, daily live weight gain was significantly higher for MP than HP or SP lambs (P<0.01). However, this was solely due to greater gut fill for MP lambs compared to HP and SP lambs (P<0.05). There were no significant treatment effects on mean carcass weight. However, all treatments significantly (P<0.05) reduced GR tissue depth (measured on hot carcass at slaughter) by 20%, 19% and 24% for MP, HP and SP lambs, respectively. Chemical fat content in the carcass significantly decreased (8%, 12% and 16%, respectively (P<0.05)). Differences between dietary treatments were not significant for these traits. M. longissimus dorsi area and protein content of the carcass were not significantly altered by dietary treatments (P>0.05). It is concluded that carcass fat in overfat lambs can be successfully reduced by feeding diets low in energy and supplemented with medium to high levels of protein without adverse effects on carcass protein. High levels of dietary protein do not appear to be necessary for this to occur.

The relationship between internal parasite burden, faecal egg count, and mucosal mast cells in fleeceweight-selected and control sheep - Williamson JF; Blair HT; Garrick DJ; Pomroy WE; Douch PGC (Proceedings of the New Zealand Society of Animal Production, 1994)
Research has shown that sheep from a Massey University flock selected for increased fleece weight (FW) for thirty-six years have higher faecal egg counts (FEC) than unselected controls (C). The purpose of this trial was to determine whether differences in FEC between FW and C sheep accurately reflected differences in adult worm burdens. In addition levels of mucosal mast cells, and their relationship with worm burden in each line were examined. Thirteen one year-old rams from each flock were housed indoors and artificially infected with larvae of three species of nematode parasite: Haemonchus contortus, Ostertagia circumcincta, and Trichostrongylus colubriformis. FECs were monitored and adult worm burdens, and levels of mucosal mast cells, determined following slaughter 28 days after infection. FECs were higher in FW than C sheep (4204 vs 300 epg, p<0.0001), as were numbers of adult Haemonchus (1151 vs 249, p<0.01) and Ostertagi (2268 vs 600, p<0.05). Numbers of Trichostrongylus (5838 vs 5266) and total worm burden (9257 vs 6115) were not significantly different between lines. A 'Total Pathogenic Index', calculated from the number of parasites of each species present in the total burden, was higher in FW than C sheep (3.8 vs 1.5, p<0.005). The regression coefficient relating FEC to worm burden was larger in FW than C sheep (0.35 vs 0.05 eggs per g faeces/worm, p<0.01). Levels of mucosal mast cells did not differ significantly between lines, but were inversely related to number of worms in FW sheep. There was no such relationship in C sheep. It is concluded that while the large differences in FEC between lines overestimates the difference in total worm burden, FW sheep do carry significantly more worms of the abomasal species H. contortus and O. circumcincta than C sheep. FW sheep are able to maintain superior wool production in spite of this potentially more pathogenic worm burden. The mucosal mast cell response to parasitic infection also appears to have been changed by selection.

Relationships between major milk whey proteins in blood plasma and milk yield in dairy cattle. - Morris CA; Davis SR; Eichler SJ; Cullen NG (Proceedings of the New Zealand Society of Animal Production, 1994)
We have examined the ability of co-cultured mouse mammary fat pad (MFP) to modulate the response of mouse mammary epithelial cells to a number of mitogens in vitro. In a series of 4 experiments, COMMA-1D cells were cultured with or without epithelium-free MFP obtained from the abdominal mammary glands of 23-day old virgin, female BALB/c mice. Final cell number was quantified as total DNA after 7 days. The main effect of MFP was significant in all experiments, MFP alone inducing a 6.1 to 8.2-fold increase in cell number relative to basal medium (BM) controls (P<0.001). Furthermore, this stimulatory effect of MFP synergised (P<0.02) with the mitogenic effect of 10% foetal calf serum (FCS). Examination of the response to several mammogenic hormones indicated that insulin (10 ug/ml) alone did not increase cell number (P>0.05), and interacted with the effect of MFP (P<0.001). There was no effect of prolactin (2.5 ug/ml) either alone or with MFP, whereas hydrocortisone (2.5 ug/ml) attenuated the response to MFP (P<0.001). In the absence of MFP, insulin-like growth factor-I (IGF-I; 75 ng/ml) did not increase cell number (P>0.05), whilst epidermal growth factor (EGF; 25 ng/ml) significantly increased cell number 3.7-fold. Both of these growth factors markedly interacted with the effect of MFP (P<0.001). When cultured with the combination of these growth factors and MFP, the final cell number was 29.2 times that of BM alone (25.14 ± 0.84 vs 0.86 ± 0.12 ug DNA/well). There was no effect of prostaglandin E2 (PGE2; 0.5 ug/ml) or indomethacin (5 mg/ml), an inhibitor of prostaglandin synthesis, in the absence or presence of MFP. These findings demonstrate that a diffusible factor(s) from the MFP interacts with several regulators of mammary growth to markedly stimulate epithelial proliferation in vitro. Such a factor appears distinct from a number of classical mitogens, and may be involved in the regulation of mammary development in vivo.

Remote Blood Sampling Device A stress free blood sampling technique for free ranging animals - Ingram JR; Matthews LR; McDonald RM (Proceedings of the New Zealand Society of Animal Production, 1994)
Changes in various blood parameters can be used to assess the relative stressfulness of farm practices. In order to overcome confounding effects of stress inherent in standard methods of blood collection, a portable remote blood sampling device ("Dracpac") has been developed and tested. Twelve heparinised blood samples can be taken from the jugular vein and stored in insulated packs on the animal. The stability of blood parameters taken from and stored on red deer was determined. Analyses of subsamples taken from a bulk initial sample over 12 hours showed that levels of cortisol, haematocrit and glucose did not significantly differ from initial values. In a second experiment stags were sampled remotely during restraint in a mechanical crush and subsequent recovery at pasture on 2 successive days. On both days cortisol, haematocrit, glucose and lactate levels were elevated during restraint and thereafter decreased significantly to reach levels substantially lower than previously reported for this species using standard methods of blood sampling. The development of this device permits reliable remote blood sampling of free ranging animals without the stress associated with manual blood sampling.

Repeatability of seasonal wool growth in Merino Sheep - Sumner RMW; Clarke JN; Pearson AJ; Speedy PM (Proceedings of the New Zealand Society of Animal Production, 1994)
Wool samples were clipped from the midside of 27 Merino rams and 33 unmated Merino ewes born in 1990 at 4 or 8 weekly intervals, depending on the season, between July 1991 and January 1994. Wool growth rat and mean fibre diameter were measured. Both wool growth rate and mean fibre diameter exhibited seasonal growth cycles which were synchronous. The rhythm of the seasonal cycle for each characteristic was calculated as:- Rhythm (%) = (Max-Min) / ((Max+Min) / 2) x 100 The rhythm for wool growth rate exceeded that for mean fibre diameter while the rhythms for both characteristics increased significantly between the first and second year but not between the second and third years. Although wool growth rate and mean fibre diameter were strongly correlated between adjacent clipping periods, the derived rhythm estimates for both characteristics were only weakly correlated between years. Adjustment of the rhythm estimates for liveweight change during the same period significantly improved between sheep repeatability of the seasonality estimates. These data indicate that a significant proportion of the variation in both wool growth rate and mean fibre diameter was, after adjustment for liveweight change, associated with permanent phenotypic differences among the sheep in the rhythm of their seasonal wool growth cycle.

Reproductive performance of ewes after grazing on G27 red clover, a low formononetin selection in cultivar Pawera. - McDonald MF; Anwar M; Keogh RG (Proceedings of the New Zealand Society of Animal Production, 1994)
One hundred and fifty ewes grazed either on a high oestrogenic red clover (Pawera), or a new, low oestrogenic selection of red clover (G27), or control pastures before mating. The treatment groups (n = 25) and grazing lengths prior to mating were (1) Pawera, 6 weeks; (2) G27, 6 weeks; (3) G27, 12 weeks; (4) G27/Ryegrass-white clover (rg-wc), 6 weeks/6weeks; (5) Rg-wc (control 1), 6 weeks, and (6) White clover (control 2), 6 weeks. The ewes were mated as one group on rg-wc pasture immediately after the grazing treatments. Formononetin concentration was significantly lower in G27 (0.26%) than in Pawera red clover (0.55%) (P<0.05). Ovulation rates in ewes after the first service were similar for all treatment groups (P<0.05). The incidence of return to service was significantly higher in Pawera ewes (72.7%) than in any of the other groups (P<0.01). The return rates for the other groups were 33.3% (G27/6weeks), 25.0% (G27/12 weeks), 4.8% (G27/rg-wc), 9.5% (rg-wc) and 14.3% (white clover). Most ewes which were mated at the next two cycles became pregnant. It is concluded that the fertility in the ewes grazing G27 red clover was better than that in ewes grazing Pawera red clover, however there may have been some impairment in contrast to animals grazing control pasture.

Residual effect of a four weeks grazing of oestrogenic red clover on reproductive performance of ewes in the following six weeks. - Anwar M; Keogh RG; McDonald MF (Proceedings of the New Zealand Society of Animal Production, 1994)
The trial was conducted to study if the temporary infertility in ewes induced by oestrogenic clover, would recover accompanied by a concomitant increase in ovulation rate and/or litter size following their removal to a 'safe' pasture. Romney ewes (N - 155) either grazed on Pawera red clover or Ryegrass-white clover (control) pasture for four weeks. Afterwards all ewes grazed ryegrass-white clover pasture and were mated in 3 groups either at the first, third or sixth week post-treatment. Mean ovulation rate was significantly lower (P<0.05) in the Pawera ewes (1.22 ± 0.06) than in the controls (1.49 ± 0.07) on respective treatments after two weeks of grazing. Ovulation rates in ewes after the 1st, 2nd and 3rd mating cycle were 1.60 ± 0.12, 1.41 ± 0.10, 1.27 ± 0.09 (red clover), and 1.64 ± 0.10, 1.67 ± 0.12, 1.30 ± 0.90 (control) respectively. Ovulation rate and litter size were similar for the two treatment groups after joining in week 1, 3 or 6 post-treatment (P>0.05). No increase in ovulation rate/litter size in Pawera group ewes was observed over and above those observed in the control ewes within the six week post-treatment period.

Responses to selection for lean tissue growth in Dorset Down sheep - Nsoso SJ; Beatson PR; Young MJ; Logan CM (Proceedings of the New Zealand Society of Animal Production, 1994)
Responses to selection using a lean tissue growth index were estimated from performance data of the Lincoln University Dorset Down flock. Data were available for ewes (n=922) born in the years 1984 - 1991 and rams (n=816) born in 1984 - 1992. Data were from two closed lines, one control and the other selected for high lean tissue growth. Initially selection was on the basis of an index comprising measurements of live weight and fat depth. Subsequently muscle depth was incorporated into the index. Ewes and rams born in spring each year were run separately at pasture from weaning (late summer) onwards. Performance testing was in the following autumn for ewes and winter for rams. Measurements were live weight and in vivo ultrasonic fat and muscle depths. Responses were calculated from regression of the difference between the line means for breeding value against time. Breeding value estimates were derived by AIREML analyses. Both sexes exhibited desirable responses in all component traits: rams; +0.290kg/yr, +0.019mm/yr and -0.013mm/yr and ewes; +0.154kg/yr, +0.028mm/yr and -0.028mm/yr for live weight, muscle and fat depths respectively. Increases in muscle depth occurred after it was incorporated into the selection index.

Risk perceptions and management responses to risk in pastoral farming in New Zealand. - Martin SK (Proceedings of the New Zealand Society of Animal Production, 1994)
The environment facing pastoral farmers in New Zealand is much more risky than it was a decade ago. This has required primary producers to identify their sources of risk and to take measures to protect their businesses against these risks. A nation-wide postal survey of 1750 dairy, sheep and beef and deer farmers was undertaken in July 1992 to determine the importance which pastoral farmers attached to different risk sources and strategies for managing risk in the post-deregulation environment. Usable responses were received from 885 farmers. A follow-up telephone survey of non-respondents found no evidence of non-respondent bias. Farmers in all three groups considered business risk to be higher than financial risk, with changes in product prices being the most important risk source. Other important risks were changes in the world economic and political situation, changes in New Zealand's economic situation, changes in input costs (except for deer farmers), rainfall variability, pests and diseases (for deer farmers), changes in producer board policies (for dairy and deer farmers), changes in government laws and policies (for deer farmers) and risks associated with accidents or health problems. A range of management responses were used to combat risk. For all three groups of farmers, routine spraying and drenching and maintaining feed reserves were the most important risk management responses. Keeping debt low, managing capital spending and maintaining both short and long term flexibility in farming operations were also considered important. Sheep and beef cattle and deer farmers also consider the marketing responses of market information, spreading sale and having more than one enterprise to be important.

The role of systems research in animal science - McCall DG; Sheath GW; Pleasants AB (Proceedings of the New Zealand Society of Animal Production, 1994)
This paper presents challenges to the way we conduct experimentation in animal science. The theme of the paper is to show the benefits of using systems research methods in both our basic and applied animal science. The need for more accurate prediction of biological processes to achieve future breakthroughs in animal production is postulated. The use of systems research using dynamical systems models in our basic science to better understand and predict the outcome of complex biological processes is discussed. In the applied science context, difficulties in translating basic (component) research results into recommendations for improved farm performance are emphasised. Equally, difficulties in designing interpretable farm system experiments are acknowledged. Finally, examples are given of the benefits of using whole farm models to integrate component results and create a link between component research and improved farm system, field, experimental approaches.

The role of women in livestock production in eastern Turkey - Aspinall JM; Thompson KF; Hart ND (Proceedings of the New Zealand Society of Animal Production, 1994)
As part of a livestock consultancy in eastern Turkey Lincoln International consultants surveyed rural women to define their role in livestock management and their priorities for extension. The results of group interviews of 200 women in 19 villages showed that men are the agricultural decision makers, except in the few villages where men have off-farm employment. Women are responsible for milking of animals. They may assist with lambing and calving, cleaning animal houses and feeding stock. Women were aware of the effects of animal disease and poor nutrition on animal productivity, effects they observed during daily milking. They expressed an interest in receiving information on animal health. Non agricultural problems identified were effective family planning, education for girls, and water supply for those villages without water piped to a central location.

Selection for or against facial eczema susceptibility in sheep - Morris CA; Towers NR; Wesselink C; Wheeler M (Proceedings of the New Zealand Society of Animal Production, 1994)
Facial Eczema (FE) in sheep is associated with liver damage and considerable production losses. Romney flocks, resistant (R) and susceptible (S) to FE were established at Ruakura in 1975; a control (C) and a second resistant (R2) flock were added after 1981, the R and R2 flocks were merged in 1988, and three flocks (R, C, and S) still exist. Progeny testing was carried out in early years for ram selection, and performance testing was used after 1981. The R flock was dosed with sporidesmin in most years since 1981 at 0.15 mg/kg live weight, with the dose rate for the S flock initially 0.066 mg/kg and now reduced to 0.04 mg/kg. The C flock was divided into two groups, with one group dosed at 0.15 and one at 0.04 mg/kg, to provide an indirect comparison of the R and S flocks. Blood samples were taken after dosing to monitor liver damage via plasma gamma-glutamyltransferase (GGT) concentration. Loge GGT levels increase in proportion to increasing severity of liver damage. Thus, changes in mean loge GGT value reflect changes in relative susceptibility or resistance, with negative changes indicating increasing resistance. Two distinct peaks appear in the loge GGT distribution, centred around values of about 40 and 500 international units (i.u./l) for both the R and S flocks. The selection flocks differ in the proportions of animals at each peak, suggesting that the R and S flocks may be indirectly compared via the C flock although different dose rates were used. Annual divergence in loge GGT in the R flock relative to the C flock was -0.081±0.047 i.u./l, and the R-flock difference from control in the most recent years averaged -1.24±0.14 i.u./l. Divergence of the S flock from the C flock was more variable from year to year and the S-flock difference from control for the last 6 years averaged 0.48±0.11 i.u./l. A total of 101 industry flocks have used the commercial FE testing service, Ramguard, with 9 of them testing for at least 10 years. A comparison with the Ruakura R-flock response was obtained from one such flock selecting for production traits and FE resistance since 1979. Their GGT trend was 34% of the R-flock trend, indicating that less but worthwhile genetic progress has been obtained from using a selection programme with a multiple objective.

Separating dead from live sperm in thawed frozen merino semen does not enhance conception rate - Brief Communication - van Reenen GM; Griffin JFT (Proceedings of the New Zealand Society of Animal Production, 1994)
No abstract supplied

Some effects of feeding pasture silage as a supplement to pasture on reproductive performance in lactating dairy cows - McDougall S; Clark DA; Macmillan KL; Williamson NB (Proceedings of the New Zealand Society of Animal Production, 1994)
Supplementation of a ryegrass/white clover pasture diet with pasture silage is a common management practice in New Zealand dairy herds. The effect of this supplementation during early lactation on reproductive performance has not been investigated. Five herds of 20 cows were formed before calving commenced on June 1 1992. From August 5 to September 4, two of these herds were fed 5 kg dry matter/cow/day of pasture silage in addition to the ryegrass/white clover pasture offered to all herds. Pasture silage supplementation did not alter the intervals from calving to first ovulation, first oestrus, or to conception. However, it reduced the first service conception rate(37.5% vs 53.3%; (sed = ± 10.0%), for pasture and silage and pasture only cows; respectively). A positive effect on reproductive performance of pasture silage supplementation was not demonstrated in this trial

The stock unit system - fair treatment for the breeding cow? - Crawford HK; Lowe KI (Proceedings of the New Zealand Society of Animal Production, 1994)
The stock unit (SU) system has been widely used in conjunction with gross margin (GM) and analysis to make recommendations to farm managers on the comparative profitability of pastoral livestock systems. This information can be misleading, particularly where beef breeding cow policies are being compared with finishing cattle policies that involve high rates of liveweight gain (e.g. bull beef production). To illustrate the deficiencies of the SU system for standardising between different livestock enterprises, relative gross margins per stock unit (RGM/SU) were derived for two case study farms in contrasting environments. One property was located in the Manawatu region (Tuapaka), the other at Port Waikato (Limestone Downs) in South Auckland. Using the breeding cow as a base (=100), the RGM/SU at Limestone Downs for breeding ewes, bull beef, steer finishing and once bred heifers were 70, 158, 74 and 121, respectively. If these RGMIsu were expressed in terms of returns per kilogram of pasture consumed ($/kg) the rankings, relative to breeding cows (=100), were breeding ewes (51), bull beef (95), steer finishing (53) and once bred heifers (106). Corresponding values for breeding ewes and bull beef at Tuapaka were 59 and 65. Thus, the substitution rates between livestock enterprises varied substantially depending on the method used to account for differences in feed consumption. The implications of these findings for farm management decision making are discussed.

Think globally, act locally - Roles for science in enabling local actions for sustainable resource management behaviours. - Saunders LS (Proceedings of the New Zealand Society of Animal Production, 1994)
Behavioural responses are prerequisites to sustainability and essential if the Think Globally, Act Locally concept is to become a reality. The introduction of the Resource Management Act adds weight to the requirement for land users to Act Locally, through enabling land use within the stated purpose of sustainable management of resources. The provision of knowledge to enable land users to Act Locally is one of the priority roles for science, in order that the collective values of society are supported. It is postulated that the sustainable management of resources is likely to be symbolic and may have little direct influence on behavioural outcomes. Science needs to identify the utilitarian values associated with equity, efficiency, effectiveness and knowledge itself to enable local action. Local action will in turn support the symbolic beliefs of society at large. Failure to enable local action will result in society judging science on the basis of declining sustainability i.e. symbolic and the possibility of reduced public funding for future research. A number of new science interrelationships involving society, policy and other science providers are recommended.

Timing single fixed-time inseminations in ewes: Some new concepts - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1994)
The mean interval from the end of synchrony treatment to the onset of oestrus can be highly variable and as a consequence 'single-time' inseminations may occur at other than optimal times. This study was undertaken to identify some of the factors influencing the interval to oestrus following synchrony treatment, and to develop a spreadsheet model to assist with determining the timing of AI in ewes under a range of oestrous onset patterns. Synchrony device, PMSG, time of year, and live weight tended to have important effects on the interval to oestrus. Ewe genotype and year effects were generally small. Three new concepts have arisen from the modelling exercise. Firstly, the actual timing of AI to achieve near maximum fertility depends on the mean interval to oestrus in a given flock, but not the precision of synchrony or the incidence of ewes that are synchronised. Secondly, the 'tolerance' about this optimum time of insemination depends on how much is known about the mean interval to onset (more information means more tolerance). Thirdly, the 'tolerance' about this optimum time of insemination depends on the maximum reduction in flock pregnancy rate that is acceptable to the flock owner (higher reduction means more tolerance). If the onset pattern in a particular flock is unknown, the 'universal' timing for a single fixed-time AI during the breeding season is 42- 46 h after CIDRÆ removal, provided a drop in flock pregnancy rate of up to 5% is acceptable.

Ultrasound measurements predict estimated adipose and muscle weights better than carcass measurements. - Young MJ; Deaker JM (Proceedings of the New Zealand Society of Animal Production, 1994)
Seventy-six 6 month old Coopworth ram lambs were scanned with ultrasound for muscle depth B, fat depth C and tissue depth GR. Lambs were slaughtered, then B, C and GR measured directly on each carcass. The hindquarters (loin and hind legs) of each carcass were boned out and soft tissue minced then analysed for lipid and protein content. From these, hindquarter adipose and muscle weights were estimated. Correlations of estimated tissue weights with ultrasound measurements were consistently higher than those with direct measurements (averaging 0.423 versus 0.293, respectively). The latter method may be more prone to measurement errors associated with displacement, damage or distortion of tissue or positioning of the measurement site. It is concluded that ultrasound measurements may be better than those made directly on the carcass for predicting tissue weights.

Use of a grazing model to study management and risk - Cacho OJ; Bywater AC (Proceedings of the New Zealand Society of Animal Production, 1994)
A model which simulates the operation of a pastoral farm was used to perform a 'computer experiment' on an irrigated Canterbury property. The effects of seven stocking rates, ranging from 9 to 21 stock units per hectare (SU/ha), on the performance and profitability of a self-replacing sheep flock were tested. The same experiment was performed under two scenarios (deterministic and stochastic). The deterministic scenario was equivalent to a controlled experiment, where the same pasture growth pattern occurred every year, reflecting average production in the area. The stochastic scenario introduced random variation between years, reflecting the area's natural variability in pasture production. In the deterministic experiment, maximum meat production (258 kg/ha) was obtained at 21 SU/ha, while maximum wool production (89 kg/ha) occurred at 19 SU/ha. Lambing percentage reached a maximum (135%) at 13 SU/ha. Under the assumed set of costs and prices maximum gross margin was obtained by maintaining a stocking rate of 21 SU/ha. Introducing stochastic behaviour caused maximum production levels to decrease and gross margin was maximised at a lower stocking rate (17 SU/ha), reflecting the costs associated with weather variability. Results were used to examine the trade-off between profits and risk in stocking rate decisions.

The use of a marketing approach to improve the development of new technologies: A case study - Parminter TG (Proceedings of the New Zealand Society of Animal Production, 1994)
To predict farmer adoption of new technology, distinctive approaches have been developed within a number of social research disciplines. Some of these have focused on the range of personal characteristics of farmers. In others, marketing techniques have been used to analyse production limitations and farmer objectives to understand technology adoption. Biological scientists in New Zealand have in general acknowledged a role for social scientists in describing the economic and social conditions surrounding farmer innovativeness, but have seldom allowed that to influence the development of new technology. The central proposition this paper is that a marketing approach to the development of farm technologies will improve their adoption rate. A survey of farmers in New Zealand's Waitomo District has been previously reported in a study of their decisions to adopt beef breeding cow technologies (mating yearling heifers, using crossbred beef dairy cows, and terminal sires). In this paper ten attributes of the three technologies identified by farmers are reported as influencing their adoption or non-adoption decisions. When these attributes were included in logit regression equations, the equations were 70- 74% correct in predicting which farmers had adopted technologies and which had not. It is concluded that new technologies will only be adopted if they meet farmer expectations when applied within farm production systems. To improve rates of adoption, researchers need a greater understanding of the attributes of new technologies that will be used by farmers to evaluate them. This can only be achieved by involving farmers at all stages of the developmental process.

Use of simulation models in research - Bywater AC; Cacho OJ (Proceedings of the New Zealand Society of Animal Production, 1994)
Simulation models are increasingly used in animal research both independently and in conjunction with experimental research. This paper describes the potential uses of models within research programmes and categorises research into three main types, component research, systems research and management research. The contribution of models to component research into lactation, growth, wool growth and feed intake is reviewed. It is suggested that the concepts and data concerning interactions within the pastoral livestock system are now sufficient for a comprehensive modelling analysis of this system to be undertaken. The potential use of production systems models in management research is illustrated through the analysis of farm management factors affecting production and returns from fine wool using a pastoral sheep farm simulation model.

The utilisation of whole body cysteine by the mammary gland of the lactating goat - Knutson RJ; Lee J; Davis SR; Harris PM; MacKenzie DDS; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1994)
Three lactating Saanen goats weighing 55-71 kg, producing 1.2-3.6 kg milk/day and fed ad libitum concentrates and hay, were infused via a jugular catheter with 35S-cysteine (35S-Cys) at 9.3 mCi/min for 9 hours. Blood samples were taken hourly and mammary tissue biopsied terminally. Concentrations and specific radioactivities (SRA) of cysteine (Cys) and glutathione (GSH) were determined in whole blood, plasma and mammary tissue. Mean arterial concentrations (nmoles/g±SE) of Cys and GSH in whole blood, plasma and red blood cells were: 71±7, 79±9 and 19±8; and 823±30, 1.6±01 and 3426±124 respectively. Arterial SRA in whole blood at plateau (7-9h) of 35S-Cys (352±13 dpm/nmole) was higher than that for GSH (5.9±0.7 dpm/nmole). However the difference between intracellular SRA for Cys and GSH in mammary gland tissue was much less (231±23 vs 146±13 dpm/nmole). Total uptake of Cys by one half of the mammary gland was 0.5±0.2 g/day. Whole body irreversible loss rate of Cys was 7.3±0.7 g/day, giving a percentage utilisation of whole body Cys by the mammary gland of 13.6±4.3.

Variable animal performance and farm diversification - Dake CKG (Proceedings of the New Zealand Society of Animal Production, 1994)
Distributions of gross margins of breeding ewe, breeding cattle and plantation forestry enterprises were used in a linear programming model of a 651 ha Taranaki hill country pastoral farm to determine the mix of enterprises that maximised expected net farm revenue for given levels of downside risk. Risk was specified as the mean negative deviation of farm revenue from an assumed target income of $180,000. Animal performance variables used in estimating gross margins included (mean, minimum, maximum) (a) lambing percentage (92, 87, 99), (b) wool weight-kg per stock unit (5.4, 5.1, 5.8), (c) calving percentage (85, 83, 88) and (d) bull beef carcass weight-kg (229, 208, 247). The enterprise mix of 250 ha forestry and 3,791 stock units of bull beef yielded an optimum expected net farm revenue of $497,591 with little or no downside risk. Breeding ewe and breeding cow enterprises did not contribute to the optimum enterprise mix. Using a sheep/cattle ratio of 70/30 stock units, the expected net farm revenue reduced to $348,884. The optimum enterprise mix, with this ratio, was 310 ha forestry and 3,310 stock units of bull beef and sheep. The model predicted that it would be possible to increase the expected net farm revenue to a maximum of $362,923 by increasing the acceptable downside risk and the area allocated to forestry.

The variation in milk composition from individual Beta-lactoglobulin AA and BB phenotype cows - Hill JP; Paterson GR (Proceedings of the New Zealand Society of Animal Production, 1994)
Studies in New Zealand have shown that bulk milk collected from groups of ·-lactoglobulin AA phenotype cows has a different composition to bulk milk collected from groups of þ-lactoglobulin BB phenotype cows (Hill, 1993). Although all cows used in this study were different to those used by Hill (1993), differences in composition were similar with the ·-lactoglobulin AA phenotype cow group producing milk which contained less casein, fat and total solids than ·-lactoglobulin BB phenotype cow group. No significant differences was observed in the total protein, lactose or ash content in the milk of the two phenotype groups. In comparison with the þ-lactoglobulin AA and BB phenotype bulk milks, large variations in composition were observed in the milk from individual cows. As all cows were fed on identical pasture and subjected to identical farm management practices these results indicate that in addition to þ-lactoglobulin phenotype other genetic factors can have a significant influence on the composition of milk.

Variation in the pH of lamb meat within and between sheep breeds - Bray AR; Young SR; Scales GH (Proceedings of the New Zealand Society of Animal Production, 1994)
Serial measurements of the pH of the longissimus dorsi muscle were obtained from lambs of 22 sire groups of six sire breeds (Experiment 1) and in 14 sire groups of lines selected for Fast and Slow Glucose Clearance (Experiment 2). Lamb sex (ewe, wether) and carcass weight and leanness had little effect on meat pH. Sire breed had significant effects on pH at 1 and 24 hours post mortem, and selection line had significant effects between 1 and 4 hours post mortem. These effects were greater on slaughter dates when pH levels were higher. Variation between individual sires was sufficient to account for some differences between sire breeds and selection lines. Differences between sire breeds and selection lines were found from the time of first pH measurement after slaughter through until ultimate pH was reached. This suggests that there were differences in the rate of glycogen breakdown to lactic acid immediately after slaughter or during electrical stimulation, as well as differences in the amount of glycogen in the muscle at slaughter. These findings confirm that lamb genotype can influence meat pH and thus will affect commercially important meat properties.

Voluntary feed intake, growth and efficiency of feed conversion in growing sambar (Cervus unicolor) and red deer (Cervus elaphus) - Semiadi G; Muir PD; Barry TN (Proceedings of the New Zealand Society of Animal Production, 1994)
Hand-reared sambar and red deer (3 hinds and 5 stags/species) were confined indoors in individual pens and fed a pelleted diet ad libitum, to study seasonal effects upon voluntary feed intake (VFI) and body growth. Mean age at the start of the experiment was 5 months for sambar and 7 months for red deer. Red deer of both sexes showed maximum VFI and liveweight gain (LWG) in summer and minimum values in winter. Sambar of both sexes also showed seasonal cycles in VFI and LWG, but with maximum values in autumn and minimum values in spring, and with the amplitude of the cycles being much less than for red deer. Over a complete 12 month period (7-19 months of age), total LWG was similar in sambar and red deer, but total VFI was lower for sambar (p<0.01) and efficiency of food conversion (kgDM/kgLWG) more efficient for sambar than for red deer (p<0.05). When energy requirements were calculated, the amount of metabolisable energy (ME) required for both maintenance and gain were lower for sambar than for red deer.

Within herd variability in the mineral status of grazing dairy cows in early lactation. - Dalley DE (Proceedings of the New Zealand Society of Animal Production, 1994)
Two groups of 10 mature, crossbred cows received either a single daily dose of 10 g Mg or no supplemental Mg for two 5 day periods. Blood was sampled twice daily and urine once daily. On 3 days blood and urine were sampled four times. Serum Mg levels of 3 unsupplemented animals fell from 0.74 ± 0.034 to 0.25 ± 0.020 mmol/1 within 5 days while other animals within this group maintained serum Mg levels despite the absence of Mg supplementation. At any given sampling time serum Mg levels of individuals within the unsupplemented group varied from 0.22 to 0.88 mmol/1 and those of supplemented animals from 0.41 to 0.83 mmol/1. Mean serum Mg, Ca, Na and K concentrations did not differ between the groups. Unsupplemented animals had significantly (P<0.001) lower urinary fractional clearance ratios of Mg and Ca. The within and between animal variation in serum Mg levels was high for both Mg supplemented and unsupplemented animals. The fractional clearance of Mg in urine indicated a likely benefit from Mg supplementation for 100% of the unsupplemented animals while serum Mg concentrations only identified 40% of these animals. Fractional clearance of Mg in urine has potential as an indicator of animal Mg status.

Wool characteristics of fine-wool sheep in Xinjiang Uygur Autonomous Region, China - Wang XL; Lu W; Saremu; Andrews RN (Proceedings of the New Zealand Society of Animal Production, 1994)
Wool production characteristics were investigated for fine-wool sheep of different genotypes at Nanshan Stud Farm, Xinjian Uygur Autonomous Region, China. Four main sets of data were available. The 1985 ewes were mixed-age Xinjian Finewool (XF). The 1986 ewe and ram hoggets were XF, F1 Australian Merino (AM) x XF and F1 Chinese Merino (CM) x XF. The 1987 ewes included CM, mixed-age XF, F1 AM x XF 2 year olds and F1 AM x XF hoggets. The 1987 rams included AM, CM and mixed-age XF. Observations were made and samples collected at shearing in June. Measured traits included: -body weight (BW); greasy fleece weight (GFW); clean yield (CY); clean fleece weight (CFW); fibre diameter (FD); crimp frequency (CF); staple length (SL): colour (CL); weathered tip (WT); dirt (DT). dirt penetration (DP): suint (SU, and wax (WX). Significant differences (P<0.05)) occurred between hogget genotype and between sexes. AM x XF hoggets produced more wool than CM x XF, or XF, but there were no differences in BW. Ewe and ram hoggets had similar BW's, but ewe hoggets produced more wool of lower FD with greater SL and WT. In the XF ewes, as age increased there were significant (P<0.05) changes in GFW, CY, CFW, SL and WX. Clean fleece production of 3-6 year old XF ewes declined by 0.17 kg/yr and SL by 0.33 cm/yr. In the XF rams, there were significant (P<0.05) increases in BW and DT with age, whilst wool production increased to 3-4 years and then declined. There were significant (P<0.05) differences between years in GFW, FD, SL, WT, DP, DT, WX and SU in hoggets, and CY, CFW, FD and SL in mature ewes. The 5 body sites of XF ewes in 1985 had significant (P<0.05) differences in fleece traits for FD, SL and CL. There were significant (P<0.001) correlations between traits for pooled data from all genotypes, ages, sexes, years and sampling sites. Negative correlations included WX with WT, DP, and DT; and DT with CY; whilst DP was positively correlated with WT. These results have implications for future sheep breeding and wool technology research, and development of programmes for improved clean wool production and quality in China.

Animal toxicity problems perceived to be associated with different pasture types on East Coast sheep/beef farms - Korte CJ; Smith DR (Proceedings of the New Zealand Society of Animal Production, 1993)
An understanding of behavioural principles such as the flight zone, 360 degree vision, sensitive hearing, strong reactions to novelty and effects of pressure on the body will facilitate handling and restraint of livestock. Silencing high pitched noise from hydraulic pumps and motors will reduce stress. Solid fences on races, crowd pens and loading ramps will keep animals calmer by blocking their vision. A curved race to a crush or stunning box will facilitate cattle movement because an approaching animal will not be able to see people at the other end. Wild cattle will stand still in a dark box for AI. Wild cattle in a restraint device will remain calmer if they are unable to see people inside their flight zone or a pathway of escape. It is important to keep vision blocked until the animal is completely restrained. Restraint devices should only apply sufficient pressure to hold the animal snugly in a comfortable position and to make the animal "feel restrained" without any pain or discomfort. Pressure applied with a slow steady movement will keep cattle calmer but pressure applied with jerky sudden movement causes excitement. Handlers and equipment engineers who utilize these principles can move and restrain livestock more efficiently with less stress and carcass damage. Rough handling is one of the major causes of carcass damage.

Animal welfare - a threat or an opportunity for research, farming and trade - Bayvel ACD (Proceedings of the New Zealand Society of Animal Production, 1993)
An enzymeimmunoassay (EIA) for measuring oestrone sulphate (OS) concentrations in cows' milk is described. The EIA utilizes a coated antigen format in conjunction with a monoclonal antibody to OS, and is performed in microtitre dishes. An enzyme label allows OS concentrations to be quantitated by measuring changes in colour density. The EIA can be completed in under 3 h, has a sensitivity of <5 pg, and allows OS concentrations to be measured directly in small quantities (0.05 ml) of whole milk. Measurement by EIA of OS concentrations in milk samples collected throughout pregnancy confirmed the progressive rise in OS concentrations described previously using radioimmunoassay. In addition, comparison by EIA of OS concentrations in milk samples from pregnant and non-pregnant cows indicated that the EIA could be used to accurately identify pregnancy status in cows sampled 120 or more days after mating/insemination. The EIA may have a role in the dairy industry for monitoring pregnancy status.

The application of controlled calving and breeding programmes to the management of large dairy herds - Armer CC; Macmillan KL; Jellie HP (Proceedings of the New Zealand Society of Animal Production, 1993)
Human synthetic parathyroid hormone-related protein (PTHrP) increased mammary blood flow (MBF) following close-arterial infusion via the external pudic artery of lactating goats. MBF increased 74

An appraisal of the utility of primary cell culture from sheep udders to investigate the control of mammary function - Wheeler TT; Callaghan MR; Davis SR; Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied.

As applied agricultural scientists we serve....? - McRae AF (Proceedings of the New Zealand Society of Animal Production, 1993)
The timing of changes in mammary epithelium cell tight junction integrity and mammary blood flow during a 36-h milk accumulation was studied in six lactating (2208

Awassi lamb performance in New Zealand quarantine - Hill FI; Ryan T; Death AF (Proceedings of the New Zealand Society of Animal Production, 1993)
Effects of preslaughter stress and postslaughter ageing regimes on calpain activities and indicators of meat quality were investigated in lambs selected for Fast and Slow glucose clearance (GC). Loins were aged at 11- 17 C for 4, 22 or 70 hrs and then stored frozen (-20 C) or chilled (0 C). Loins aged up to 70 hrs from Fast GC lambs that were exposed to a high level of preslaughter stress had the highest pH and lowest residual glycogen (P<0.05). Calpain activity and cooked meat shear force declined rapidly over the periods of ageing, with significant differences being found between 4 and 22, 22 and 70 hrs aged loins (P<0.05). At the same time pH increased, with a significant difference observed between 4 and 70 hrs aged loins (P<0.05). This data suggests that there is a potential conflict between the beneficial effects of ageing on tenderness and the adverse effects of ageing on the elevation of pH. Calpain I and II activities declined at different times after slaughter in loins aged 22 hrs and then stored chilled for 8 weeks. The loss in calpain I activity was closely associated with a large reduction in shear force over the first 22 hrs after slaughter. The results suggest that an understanding of the factors that control calpain activities may identify methods of improving meat tenderness.

Behavioural quantification of welfare in farmed red deer - Pollard JC (Proceedings of the New Zealand Society of Animal Production, 1993)
An experiment was carried out at Tokanui (Te Awamutu) and Wallaceville (Upper Hutt) over 4 years to test for the presence of sire by location interactions for faecal nematode egg count (FEC), using Romney rams from the flocks at these locations selected for high (H) or low (L) FEC. A total of 14 Tokanui rams (8H and 6L) and 12 Wallaceville rams (7H and 5L) were used in their flock of origin in the mating years 1986-90 and then in the other location in 1988-91. There were 491 lambs recorded for FEC at Tokanui, and 875 at Wallaceville. A test of the sire by location interaction was obtained by treating records from the two locations as different 'traits', and estimating the genetic correlation between them. Estimates were made on log transformed FEC from lambs recorded in January and again in March. Fixed effects were included for sire source and contemporary group (genetic group of dam, year of birth of lamb, sex of lamb), and sire was fitted as a random effect. For FEC in January, heritabilities for the two locations averaged 0.39

Beta-lactoglobulin expression in bovine mammary tissue - Ford CA; Connett MB; Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Human factors are generally recognised as influential factors affecting the welfare and productivity of farm animals, and we have proposed that in intensive animal production systems there are some important sequential relationships between the attitude and behaviour of the stockperson towards farm animals and the behaviour, performance and welfare of farm animals. Basically we have suggested that because a stockperson's behaviour towards farm animals is largely under volitional control, this behaviour is strongly influenced by the attitudes and beliefs that the stockperson holds about the animals. Furthermore, the stockperson's behaviour towards animals affects the animals' fear of humans which, in turn, may affect the animals' productivity and welfare. It is the occurrence of a stress response in animals which are highly fearful of humans which places their productivity and welfare at risk. We have published data which strongly support these interrelationships between human attitude and behaviour and animal behaviour, productivity and welfare. The results of recent research in the intensive animal industries indicate the excellent opportunity which exists to improve animal productivity and welfare by training and selecting stockpersons to have desirable attitudinal and behavioural profiles towards farm animals.