The Booroola (FecB) and Inverdale (FecXI) genes influence ovarian development in early foetal life - Smith P; W-S O; Heath DA; Hudson NL; Davis GH; McNatty KP (Proceedings of the New Zealand Society of Animal Production, 1993)
Fibre growth measurements were collected on feral (F) DOES, CASHGORA (g) AND g4 DOES. Maximum and minimum down length occurred in early August and late November in all breeds. The down fleece shed between these dates. Maximum down length was 6.7

Brief Communication - Differences in the concentrations of glucose and related metabolites in the milk of Jersey and Friesian cows - Eichler SJ; Davis SR (Proceedings of the New Zealand Society of Animal Production, 1993)
The objective of this study was to examine the effects of once daily milking (ODM) on yields of plasminogen, plasmin and other whey proteins and to investigate this possible role of plasmin in mammary gland involution. Twelve multiparous Friesian cows in the ninth month of lactation were placed on a ODM regimen for 7 days. Milk yields were determined and milk sampled for assay on the last day of twice daily milking (TDM) (day 1 of trial), days 3 and 7 of ODM (d4 & d8) and again 7 days after return to TDM (d15). Data are expressed as least-square means for d1 (TDM) vs d4 (ODM) vs d8 (ODM) vs d15 (TDM) together with pooled SE (PSE). Once daily milking was associated with a significant (P<0.05) reduction in yields of milk, lactose, fat and total protein. The concentration of plasminogen increased during ODM (0.92 vs 1.52 vs 1.37 vs 0.95, PSE = 0.06

Brief Communication - Effects of stress and nutritional changes on the ranking of cattle on plasma carotene concentrations - Knight TW; Ridland M; Hill FI; Death AF; Wyeth TK (Proceedings of the New Zealand Society of Animal Production, 1993)
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

Brief Communication - Reduced visibility lowers bull aggression - Chamove AS; Grimmer B (Proceedings of the New Zealand Society of Animal Production, 1993)
Nine Romney sheep fed fresh herbages were used to study cadmium (Cd) metabolism. The major route for the excretion of ingested Cd is the faeces with less than 0.5 percent being lost in the urine. Although there was a marked net secretion of Cd into the digestive tract post duodenually a considerable net absorption occurred from the intestinal region. Absorbed Cd is mainly accumulated in the liver and kidney (>340 ng/g fresh tissue) with much small amounts being associated with muscle (<20 ng/g fresh tissue). As the variation in the intake and excretion of Cd is large, short term balance studies are less suitable as an approach to determine the rate of apparent retention of Cd in grazing animals. The use of long term slaughter techniques and kinetic studies using stable isotopes of Cd are discussed as the preferred methods to measure the absorption and retention of Cd.

Brief Communication - The nature of the microcirculation in the mammary gland of the lactating rat - Davis SR; Farr VC; Prosser CG; Thompson JG (Proceedings of the New Zealand Society of Animal Production, 1993)
Of all farm production practices, intensive systems come under public scrutiny most, and intensive egg-production is often a particular source of concern. Caged hens are seen as unacceptable in most European countries due to the density of housing, barrenness of environment and restriction of "most normal behaviour patterns". In New Zealand most egg-production systems involve practices which are being questioned overseas in terms of their welfare impact. This paper presents the results of a survey of some representative New Zealand farms in the light of public and scientific concerns for animal welfare. Currently there appears to be no obvious system likely to replace laying cages and guarantee good welfare. Pressure for change, however, seems likely.

Brief Communication - Time and incidence of foetal mortality in alpacas - Ridland M; Knight TW; Wyeth TK; Death AF (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

A case control study of anoestrum in New Zealand dairy cows - McDougall S; Leijnse P; Day AM; Macmillan KL; Williamson NB (Proceedings of the New Zealand Society of Animal Production, 1993)
Clumps of mammary secretory epithelial cells were isolated from a lactating sheep udder and their mammary function in vitro was evaluated. Initially, the cells synthesized and secreted significant amounts of casein,

Castration, tail docking and dehorning - What are the constraints? - Stafford KJ; Mellor DJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Three experiments were undertaken to investigate the possibility that forages containing condensed tannins (CT) may affect nematode parasite burdens and their significance in lambs. In the first trial, lambs were infected with a single dose of 15000 Ostertagia circumcincta and 15000 Trichostrongylus colubriformis infective lavae. Those fed Lotus pedunculatus with or without polyethylene glycol (PEG) had lower faecal egg counts, higher liveweight gains and higher faecal dry matters than lambs fed ryegrass with or without PEG (P<0.05). In the second experiment, lambs with a low, mixed natural worm burden were grazed on sulla (Hedysarium coronarium), a CT containing legume, or lucerne, for 28 days. Lambs drenched with anthelmintic and fed sulla grew faster than those fed lucerne (321 v 215 g/day P<0.05) whilst undrenched lambs had similar growth rates on both species (250 v 220 g/day). In the third experiment, heavily parasitized lambs sired by rams selected for low faecal egg count (resistant) or conventional rams (non-resistant) were grazed on lucerne or sulla for 28 days. When anthelmintic drenches were withheld, the non- resistant sired lambs grew faster on sulla than lucerne (231 v 28 g/day; P<0.0001), as did the resistant sired lambs (181 v 72 g/day; P<0.001) respectively. Drenched non-resistant sired lambs grew faster on the sulla than on lucerne and faster than the resistant sired lambs. These results suggest that forages containing condensed tannins may have an important role to play in developing lamb production systems with less reliance on anthelmintic use for parasite control.

A cell culture model to detect IGF receptor expression during the cell proliferation cycle - Ord R; Callaghan M (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

Changing the sex ratio at birth in lambs, calves and deer: Implications for productivity and genetic gain in breeding flocks and herds in New Zealand - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1993)
Progesterone (P4), oestradiol benzoate (ODB) and prostaglandin F2a (PGF) have been used separately and in combination to synchronise oestrus in cattle by reducing the luteal phase of the cycle or delaying pro-oestrus after luteolysis. This latter mechanism can result in precise synchrony but with reduced fertility. In the process of attempting to improve synchrony and fertility, a series of four trials was completed with dairy heifers. Each trial was based on the use of a CIDR-B device for 7 to 10 days with or without 10 mg ODB in a gelatin capsule and with an injection of PGF from 2 to 4 days before device removal or at device removal. The results of these trials showed that injecting PGF before device removal could improve synchrony (in terms of animals inseminated at 48 h after device removal) but reduced pregnancy rates to first insemination by 5% to 10%. Incorporating ODB delayed the post-treatment interval to oestrus and insemination with a 7-day CIDR regime but improved synchrony with a 9 or 10 day CIDR regime. If the use of ODB was combined with an injection of PGF 4 days before CIDR device removal as part of a 10-day CIDR programme, the 48 h post-treatment synchrony rate was 93% and the pregnancy rate was 56%. Excluding the ODB from this programme reduced the 48 h synchrony rate to 87% and the pregnancy rate to 45%. These results are additional evidence that combing ODB with P4 is altering ovarian follicle wave patterns with consequent effects on synchrony patterns and fertility.

Combination treatments for synchronising oestrus in dairy heifers - Macmillan KL; Taufa VK; Day AM (Proceedings of the New Zealand Society of Animal Production, 1993)
Twelve mature Romney ewes were housed and fed to maintain a constant bodyweight for 14 months. Monthly midside samples were collected and individual fibres measured by projection microscope for fibre and medulla diameter. Medullated fibres were observed in fibre diameter classes between 14 and 70

A comparison of carcass and meat characteristics and organ weights of castrate and entire male buffalo and cattle - Purchas RW; Thomson NA; Waghorn GC; Death AF (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

Comparison of seasonal wool growth pattern and colour variation in fleece weight selected and control Romney flocks - Wuliji T; Weatherall IL; Andrews RN; Dodds KG; Turner P; Wheeler R (Proceedings of the New Zealand Society of Animal Production, 1993)
Two trials were conducted to assess the effect of kiwifruit vinegar on a number of production parameters in sheep. Trial A evaluated the effect of kiwifruit vinegar (8.2g/100ml, as acetic acid) on lamb liveweight gain, fleece production (midside growth rate, yield and colour), and internal parasite burdens. Trial B evaluated the effect of kiwifruit vinegar on two-tooth liveweight change prior to mating, and subsequent fertility. In trial A 138 ewe lambs were randomly assigned to one of four treatment groups: i) "Extender 100" Albendazole drench capsule + 10 ml vinegar, ii) "Extender 100" Albendazole drench capsule only; iii) normal drenching (trigger level 1500 epg) + 10 ml vinegar, iv) normal drenching. The only trait for which there was strong evidence of an effect was wool yield which decreased in response to kiwifruit vinegar. Vinegar treated lambs tended to have reduced faecal egg counts during the period of the trial. In trial B 140 two-tooth ewes were randomly assigned to one of two treatment groups: i) 15 ml vinegar administered at 12, 8, 4 and 1 weeks prior to mating; ii) control. Reproductive status was assessed by ultrasound 38 days after removal of the ram. No significant differences were found in liveweight or in reproductive status between the group groups. Evidence from these two trials would suggest that any effect of kiwifruit vinegar on performance traits in sheep is small and not necessarily beneficial.

A comparison of the effect of split and single applications of nitrogen fertiliser on dairy production - Penno JW (Proceedings of the New Zealand Society of Animal Production, 1993)
The objectives of this study were to measure within day variation and day-to-day variation in selected metabolites in serum and milk samples obtained from animals in a herd of 20 Holstein-Friesian cows which grazed ryegrass/white clover pastures during peak lactation in October. In the first trial, the 20 cows were milk and blood sampled at 0630 h, 1030 h and 1430 h on 3 October and at 0630 h on the following day. Average metabolite concentrations in serum were within the ranges indicated by a regional laboratory as being normal for healthy cattle, but significant differences were associated with sampling time and among individual animals within this range. Blood and milk urea nitrogen (BUN and MUN) and blood beta hydroxybutyrate (BOH) concentrations increased by 1.82

The date of onset of puberty in ewe lambs as an indicator of the ability to breed out-of-season - Smith JF; Parr J; Johnson DL; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1993)
Half-sib heritability estimates were derived from ewe lamb progeny of the Woodlands Romney selection project. Ultrasonic subcutaneous fat depths (C) were measured with a Delphi probe at 5, 6, 8 and 14 months of age. Heritability estimates at each age were 0.31 (SE=0.12), 0.45 (0.11), 0.29 (0.06) and 0.28 (0.09) respectively. A Toshiba Sonolayer SAL-22A B-mode ultrasonic scanner was used to measure muscle width (A), depth (B) and GR tissue depth at 14 months of age and resultant heritability estimates were 0.07 (0.05), 0.26 (0.09) and 0.39 (0.11), respectively. Genetic correlations among ultrasonic fat depths at different ages ranged from 0.81-0.95 (SE 0.06-0.12) with higher values for those of closer temporal separation. Phenotypic correlations were consistently about 0.3 below the corresponding genetic correlations. Ultrasonic GR had a high heritability estimate and a high genetic correlation with fat depth at 14 months of 0.84 (0.08),but its genetic correlations with fat depths at earlier ages, were lower ranging from 0.55 to 0.72. The genetic correlation of hogget fleece weight with fat depth at 8 months of age was 0.09 (0.15), and the genetic correlation between 8 month liveweight and fat depth was 0.38 (0.13); similar relationships were found for fat depths measured at other ages. The heritability estimate for muscle depth B was moderate and close to that reported for carcass measurements. In contrast, the estimate for muscle width A was lower than reports for carcass measurements perhaps reflecting limitations in the ultrasonic technology used. The results indicate that ultrasonic measurements are useful selection criteria in breeding programmes to alter carcass traits.

Does intensive pig farming have a viable future? - Concerns over housing and welfare - Barnett JL; Hemsworth PH; Cronin GM (Proceedings of the New Zealand Society of Animal Production, 1993)
Progesterone (P4), oestradiol benzoate (ODB) and prostaglandin F2a (PGF) have been used separately and in combination to synchronise oestrus in cattle by reducing the luteal phase of the cycle or delaying pro-oestrus after luteolysis. This latter mechanism can result in precise synchrony but with reduced fertility. In the process of attempting to improve synchrony and fertility, a series of four trials was completed with dairy heifers. Each trial was based on the use of a CIDR-B device for 7 to 10 days with or without 10 mg ODB in a gelatin capsule and with an injection of PGF from 2 to 4 days before device removal or at device removal. The results of these trials showed that injecting PGF before device removal could improve synchrony (in terms of animals inseminated at 48 h after device removal) but reduced pregnancy rates to first insemination by 5% to 10%. Incorporating ODB delayed the post-treatment interval to oestrus and insemination with a 7-day CIDR regime but improved synchrony with a 9 or 10 day CIDR regime. If the use of ODB was combined with an injection of PGF 4 days before CIDR device removal as part of a 10-day CIDR programme, the 48 h post-treatment synchrony rate was 93% and the pregnancy rate was 56%. Excluding the ODB from this programme reduced the 48 h synchrony rate to 87% and the pregnancy rate to 45%. These results are additional evidence that combing ODB with P4 is altering ovarian follicle wave patterns with consequent effects on synchrony patterns and fertility.

Drying off management and the use of management aids on seasonal supply dairy farms - Parker WJ; Gray DI; Lockhart JC; Lynch GA; Todd EAG (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied.

The effect of an extended milking interval on mammary blood flow and tight junctions between mammary cells in goats - Stelwagen K; Davis SR; Farr VC; Prosser CG; Sherlock RA (Proceedings of the New Zealand Society of Animal Production, 1993)
Hereford x Friesian cows were used to compare the calf and cow performance of 66 single-calved cows (Single Cows) rearing only their own calf (Single Calf) and 45 contemporary single-calved cows (Foster Cows) rearing their own calf (Own Calf) plus a foster calf (Foster Calf). Fostering was succesful in 85% and 95% of attempts in 1990 and 1991, respectively. Mean weaning weight was lowest in the Foster Calf group but comparable in the Own Claf and Single Calf groups (140 vs 194 vs 202 kg, P<o.oo1). Single Cow and Foster Cow groups were similar in mean live weight immediately post-calving (413 vs 415 kg, NS) and at weaning time (452 vs 437 kg, NS), and the mean interval to first oestrus was about 7 weeks in both groups. Cow efficiency (ie calf weaned/kg cow post calving liveweight) was approximately doubled in the Foster Cow group. We conclude that twin-suckling dairy x beef breeding cows using a foster calf appears to be a useful option for dramatically increasing cow efficiency.

Effect of diluent and storage time on pregnancy rate in ewes after intra- uterine insemination - Smith JF; Asher GW; Briggs RM; Morrow CJ; Murray GR; Oliver JE; Parr J; Veldhuizen FA; Upreti GC (Proceedings of the New Zealand Society of Animal Production, 1993)
Liveweight gain, wool weight, wool characteristics, age of onset of oestrus and animal health data were recorded for purebred Awassi (n=37) and Coopworth (n=40) lambs in quarantine from birth to six months of age. No significant differences, between the Awassi and Coopworth lambs were recorded in: birth weight, liveweight gain (birth to weaning), and liveweight gain (weaning to 6 months). A trend for the Coopworths to have greater liveweight gains was noted. Significantly less wool was clipped from Awassi lambs (0.83

Effect of distance walked on dairy production and milk quality - Thomson NA; Barnes ML (Proceedings of the New Zealand Society of Animal Production, 1993)
A universal goal of extension agents is the attainment of voluntary behavioural changes in clients. Behaviour change occurs through the process of learning new skills. There are two distinct components to learning; grasping information through conceptualisation or experience, and: transformation of information into knowledge, through reflection or experimentation. Individual clients can be grouped into one of four distinct learning styles depending on the way they grasp information and transform it into knowledge. This paper draws upon findings from a pilot study to estimate cognitive changes occurring in a group farm monitoring programme. The results indentified learning preference and belief differences between expert and farmer roles within the group. It is suggested extension agents can target specific behaviour changes in client's by implementing strategies that use learning preference and belief data. Furthermore, it is proposed researchers can enhance levels of technology adoption by presenting research outputs using communication methods compatible with target clients' preferred learning styles.

The effect of once daily milking concentrations and yields of plasminogen, plasmin and other whey proteins - Knutson RJ; MacKenzie DDS; Davis SR; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
Lambs of ewes with a high maternal behaviour score (MBS) located the udder in less time after birth than lambs of low MBS ewes. Rapid location of the udder increased immunoglobulin concentration in lamb plasma 24 hours after birth and may contribute to the improved lamb survival and growth (ewe productivity) associated with high MBS ewes.

Effects of body covers on milk production by cows during winter, and on oxygen consumption by young calves - Holmes CW; Cayzer F; Parker WJ (Proceedings of the New Zealand Society of Animal Production, 1993)
In a study of dairy farm owners from a small geographical region and exposed to similar environmental conditions, management decisions were found to be better described by long-term goals than the commonly assumed goals of productivity and profitability. The assessment was made after analysing physical and managerial data from a two year period that included a period of drought. Farmers were interviewed to establish their long-term goals and the rationale of various farm strategies. Cognitive maps, where important concepts are mapped and linked to illustrate the line of argument, were used to represent visually, farmers goals and rationale. The long term goals of the 32 case farmers indicated that for 14 of them expansion and development was important; nine were interested in stabilising and economising; nine were looking for ways of reducing their involvement. These findings are relevant to advisers, who wish to help their client, to industries, whose goals may differ from those of the farmer, and to resource managers, who may wish to see environmental and ethical standards adopted by farmers.

Effects of CIDR withdrawal - insemination interval on conception rate in sheep AI - Paton AJ; Harvey TG; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
Prediction of ewe litter size from liveweight and body condition change over pregnancy was examined in two flocks (246 mixed aged Corriedale ewes and 154 mixed aged Romney ewes). Liveweight and body condition estimates were recorded on five occasions during pregnancy. Litter size (lambs born per ewe present at lambing) was determined at lambing. Mean liveweight at joining of ewes ultimately producing 0, 1, 2 or 3 lambs was 62.7, 63.1, 65.7 and 66.9 respectively in Flock 1. Corresponding values in Flock 2 were 57.0, 59.4, 62.9 and 68.5 kg. Liveweight change over 140 days after ram introduction for ewes carrying 0, 1, 2 or 3 lambs in Flock 1 was -2,7, 5.7, 7.4 and 9.7 respectively. Corresponding figures for Flock 2 were -6.4, - 0.6, 0.9 and 4.5 kg. Over the same period body condition declined in Flock 1 (mm GR) by 4.3, 3.4, 4.7 and 6.5 mm and in Flock 2 (units condition score, CS) by 0.37, 0.53, 0.82 and 1.00 for ewes lambing 0, 1, 2 or 3 lambs respectively. Lambs born per ewe lambing was 1.44 and 1.50 in Flock 1 and 2 respectively. Ewes are ranked within a flock on their individual deviation from the flock mean for various liveweight and/or condition criteria and allocated sequentially to nominal 'single' and 'twin' flocks of equal size. Ranking on liveweight at joining, 6 weeks prior to lambing and prior to the start of lambing resulted in a litter size in the 'single':'twin' groups of 1.36:1.52, 1.28:1.60 and 1.28:1.64 respectively in Flock 1. Equivalent figures for Flock 2 were 1.38:1.62, 1.32:1.68 and 1.29:1.71. Ranking ewes on GR (or CS) deviation from GR (or CS) predicted from the regression of GR (or CS) on pre-lambing liveweight gave some further improvement in discrimination between 'single' and 'twin' groups (1.16:1.72 for Flock 1, 1.25:1.75 for Flock 2). Depending on the accuracy required in determining ewe litter size, the use of individual ewe liveweight and to a lesser extent body condition may be an acceptable alternative to ultrasound pregnancy diagnosis.

The effects of endophyte ingestion on immune function in sheep - McFarlane RG; Bell TA; Fletcher LR (Proceedings of the New Zealand Society of Animal Production, 1993)
Midside skin and wool samples were taken at hogget shearing in October 1991 from 58 Perendale ewe hoggets which were the progeny of 2 lines of Perendale sheep selected for, or against, loose wool bulk at hogget shearing. Wool from the high line was 50% more bulky, with a 17% lighter clean fleece weight (CFW), 29% shorter staple length (SL), 25% shorter fibre length (FL), 14% greater within sample variation in fibre diameter (SDFD), 72% higher crimp frequency (CFreq), 61% higher proportion of paracortex (Para%), 92% higher follicle curvature grade (FolC) and 7% shallower follicle depth (FolD) than the low line. Character grade (Char) was 14% lower and sulphur content (S) 3% higher in the high line, each approaching 5% significance, while there was no significant difference in live weight (LW) or mean fibre diameter (FD). Bulk was most strongly correlated, in decreasing order, with FolC, CFreq, SL, FL, Para%, CFW, SDFD, Char and FolD. In decreasing order CFreq, Char, FD, SL, FL, Para% and FolD explained a total of 90% of the variation in bulk. With deletion of the subjectively assessed characteristics of FolC and Char, CFreq, SL and FL were the only characteristics selected as being significant, explaining a total of 85% of the variation in bulk. The strong association between bulk and both SL and FL can be considered to be a reflection of associations between the length parameters and other fibre characteristics which impact on bulk rather than a direct effect of the length of fibre being measured for bulk. These data indicate the biological basis of differences in loose wool bulk for coarse wool Perendale sheep are, as for the fine wool Merino, primarily associated with single fibre crimp.

Effects of melatonin implants on mating performance of Romney and Poll Dorset rams - Muir PD; Smith NB; Staples LD (Proceedings of the New Zealand Society of Animal Production, 1993)
Breed, sex and birth rank differences in follicle density and S/P ratio were examined for South African (SA) and SAxNZ Angora goats. All primary (P) follicles but few secondary (Sf) follicles were mature at birth. Density of mature secondary (Sf) follicles increased by 150% and 250% in the first month after birth, in SA and SAxNZ kids respectively. Change in P and Sf+Si follicle density followed an asymptotic slope. S/P ratio was 8.4 at birth and 9.9 at 6 months. Breed differences were apparent early in life but were not persistent to 6 months of age. Sex by birth rank interactions at 4 and 6 months of age showed that single males had an advantage over twin males in P and S density (P<0.05) while twin females had an advantage over single females (P<0.05). These differences are a likely result of differences in nutritional advantage and changes in body size. S/P ratio was unaffected by breed, sex and birthrank. The results show that initiation of S follicles after birth was likely but inconsequential. Follicle density and S/P ratio do not explain breed differences in fibre and kemp production. Comparisons with other studies suggest that the SAxNZ Angora would have a higher S/P ratio than the NZ Angora.

Effects of rumensin anti-bloat capsules on plasma magnesium concentration and aspects of health and performance of pastured dairy cows - Wilson GF; Lynch GA; Van Der Wel C (Proceedings of the New Zealand Society of Animal Production, 1993)
A total of 134 ewe lambs born in 1991 from the Ruakura "Kamo" out- of-season breeding flock were run with harnessed vasectomised rams from weaning and inspected weekly for onset of puberty and subsequent oestrus activity. The breeding values for date of lambing (BV) for these animals were calculated from a pedigree and performance database. Multiple regression analysis were performed to determine the value of factors associated with hogget oestrus for predicting BV. While all the factors analysed, date of puberty, age and weight at puberty and number of subsequent oestrus cycles, had significant effects, none were as useful a predictor as date of birth(Bday). Season of birth (autumn vs spring) also exerted considerable influence on date of first tup and number of cycles. The results indicate that the best method of selection at present is that based on date of birth. Further research is needed to understand the interaction between season of birth and BV as they influence the onset of puberty.

The effects on adoption of beef breeding cow technologies of selected farm business standards, farmer demographics, and farmer beliefs - Parminter TG; Power MPB; Shaw DC (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied

Ensiled roughages (Chaffhage and Stockhage) as feeds for young calves - Collins DE; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied

An enzymeimmunoassay to measure oestrone sulphate in cows' milk - Henderson KM; Camberis M; Simmons MH; Starrs WJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Romney rams selected for high wool staple strength grew 25% more wool than rams selected for low staple strength when fed near maintenance rations during a 10 week winter experiment. Wool growth responses to supplements of energy (6% of diet as tallow), protein (9% of diet as bloodmeal) and methionine (1.2 g/d by intraperitoneal injection) were similar in the two staple strength selection lines. Tallow increased the estimated supply of metabolic energy by 53% but was without effect on wool growth. Bloodmeal increased dietary protein by 82%, dietary energy by 9% and sulphur supplies by 15% and produced 38% more wool. Methionine injections also increased sulphur supplies by 13% but had no effect on energy or protein supplies and the wool growth response (35%) was similar to that of bloodmeal. The finding that methionine supplies limited wool growth is consistent with other studies in sheep on low planes of nutrition. A component of wool growth responses was an increase in minimum mean fibre diameter. It accounted for most differences in staple strength between treatments but comparison at the same minimum mean fibre diameter indicated that the methionine supplement increased staple strength through an additional mechanism. Staple strength responses to nutritional treatments were similar in the two staple strength selection lines. It is concluded that the greater wool growth of the high staple strength selection line accounted for the majority of its staple strength advantage over the low strength line, and that there may be an effect of methionine on wool strength that is additional to its effect on fibre diameter. Because nutritional and genetic effects on staple strength were independent, they can be exploited concurrently to reduce the incidence of tender wools.

Establishment of resistance to Haemonchus contortus by Saanen kids - Watson TG; Hosking BC (Proceedings of the New Zealand Society of Animal Production, 1993)
Four trials involving the intra-uterine insemination of a total of 840 Coopworth ewes were conducted to assess the fertilization capacity of ram semen stored at 15 C. Semen from Polled Dorset rams was collected by artificial vagina, diluted with either a standard milk diluent or a synthetic diluent (RSD-1) to a concentration of 200x10 6 sperm/ml, cooled to 15 C, placed in 0.25 ml straws and held at 15 C for various periods [Day 0 (4h), Day 1 (28 h), Day 2 (52 h), Day 3 (76 h) and Day 4 (100 h)] before insemination. Ewes were synchronised, with CIDR devices inserted for 14 days and 400 i.u. PMSG was given at time of device removal. Laparoscopic assisted intra-uterine inseminations were performed between 52 h and 56 h after device withdrawal. A total of six inseminators were used throughout the trial series with between 3 to 5 inseminators per trial. Conception rates were determined by plasma progesterone levels at day 19 and pregnancy confirmed by real time ultrasonic scanning at day 50 post mating. There were significant differences between trials in the proportion of ewes treated that exhibited oestrus prior to insemination with lower percentages in the non-breeding season. There was considerable discrepancy between the two methods of pregnancy detection. A high proportion of the non-tupped ewes deemed pregnant by progesterone were not pregnant at scanning. There were no differences between trials in the proportion of ewes pregnant after insemination with Day 0 semen. There were no significant differences between the diluents at any particular time of storage however, the overall pregnancy rate was higher for the milk diluent (50.1% v 45.0%). There was a significant effect of storage time, with the mean overall values for storage periods of 0, 1, 2, 3 and 4 days being 49.4 46.5, 40.3, 29.6 and 20.0% respectively. Significant differences between inseminations were recorded ranging from 52.6% to 35.0%. The similarity in conception rates between diluents to different storage times is in marked contrast to the estimations of percentage motile sperm obtained with these treatments. This indicates that further modification of the diluent is necessary and that for this to be achieved more critical and quantitative measurements of sperm motility and function are required.

An evaluation of a possible complementary effect of grazing goats with bulls in an intensive bull beef system - Thomson NA; Power MT (Proceedings of the New Zealand Society of Animal Production, 1993)
A field trial at Flock House over a three year period (July 1989 - March 1992) compared the performance of grazing bulls alone at three stocking rates (3.0,3.7 and 4.5 bulls/ha) with grazing bulls at 3.0 bulls/ha with an increasing stocking rate of goats (3,7, and 13 Angora does/ ha). The respective stocking rates in stock units @/ha) for the six respective treatments from bulls alone at increasing stocking rate to bulls with goats at increasing stocking rate of goats were 15,19,23,18,21, and 26 su/ha respectively. Weaner bulls were brought onto the farmlets in November each year and all rising 2 year bulls were sold off the farmiets over January to April at 18-21 months of age. Bull growth rates were significantly depressed by increasing the stocking rate of bulls but were unaffected by an increasing stocking rate of does. Bulls in the bull/goat treatment at 26 su/ha grew at a similar rate to bulls alone, stocked at 15 su/ha. Goat performance; kidding, kid fleece weight and doe fleece weight were not affected by goat stocking rate. However at the high doe stocking rate, kid liveweight at weaning and doe liveweight (March) was reduced (P<0.01 and P<0.05 respectively).  Stocking rate treatments had little effect on the economic farm surplus (variation between $680/ha for the least profitable $730/ha for the most profitable treatments).  However with a more buoyant mohai market and a more robust/productive strain of Angora goat ie. the Zimbabwe Angora, it is assumed the bull/goat system would be more profitable than bulls alone. Although goats were not complementary to bull beef production they were also not competitive with bulls over the stocking rates investigated.

The evaluation of kiwifruit vinegar as a stock feed - Williamson JF; Morris ST; Harvey TG (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

Ewe maternal behaviour score and ewe and lamb activity from birth to suckling - Parker RJ; Nicol AM (Proceedings of the New Zealand Society of Animal Production, 1993)
An experiment was conducted to examine the ability of Saanen kids to develop an effective resistance to re-infection by Haemonchus contortus. Kids were divided into three groups. Those in Groups I and III had received colostrum at birth while those in Group II were removed from their dams at birth in order to deprive them of colostrum. All kids were reared in the absence of parasites. At the start of the study they were 10-14 weeks of age. Each animal was given 350 infective larvae of H. contortus per kg liveweight during weeks 0, 6 and 17. During week 16 all kids in Group III were treated with levamisole to remove infections prior to re-infection. Faecal nematode egg counts (FEC) were determined at weekly intervals throughout the trial. All animals were killed to determine worm burdens 8 weeks after the final dosing with larvae. FEC of all groups peaked 5-6 weeks after each infection. Re-infections at weeks 6 and 17 were followed by continued declining egg counts in all three groups. Although worm counts for the three groups were not significantly different, establishment rates based on total larvae given after anthelmintic treatment were higher in Group III (15.2%) than in Group I (7.0%) or Group II (6.0%) even though both had remained untreated. Female worms dominated males when infections were superimposed (Group I - 1:0.42; Group II - 1:0.44) however, female and males were found in roughly equal proportions when infections were removed by anthelmintic prior to challenge at 17 weeks (Group III = 1.06:1). These data suggest that, in Saanen kids, recruitment into the population is affected by repeated exposure to H. contortus in the presence of an existing worm burden. One explanation is that the natural death rate may be similar to the recruitment rate however, given the similarity in worm numbers and the continuing decline in FEC across treatments, worm fecundity would have to have been depressed dramatically by some mechanism in order to effect this result. Further work is on-going to resolve these and other issues.

Experiences with on-off grazing in early lactation on dairy farms in Northland - Blackwell MB (Proceedings of the New Zealand Society of Animal Production, 1993)
In an observational study of nine commercial dairy herds over two springs (four in 1990 and five in 1991) where cows grazed pasture alone, negative associations were found between blood (or milk) urea levels and milkfat and milk protein production, and positive associations of urea levels with pasture protein to soluble carbohydrate (N/Sol.CHO) ratios. Statistical analyses using principal component analysis of two datasets from spring 1990 and spring 1991 indicated that a high proportion of variation (73% in 1990, and 33% in 1991) in the variables measured was explained by the above relationships. Analysis of variance of the PC scores showed that these relationships were between-farm effects and not related to seasonal change with time (P<0.001). Additional data from 35 dairy herds in September 1991 also supported the associations found. Reproductive performance in the nine herds (conception rate and submission rate to AB mating) was also associated negatively with urea levels. Variations in the nutrient composition of spring pasture during the spring are presented. The correlation between N/Sol.CHO ratio and milk urea levels was high (r=0.69). Further work is needed to clarify cause and effect relationships.

Expression of milk genes in ruminant mammary tissue, is it subject to local controlling factors? - Molenaar AJ; Davis SR; Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1993)
To assess whether reducing visibility would also reduce aggression in farmed bulls, we put 2 newly-formed groups of 20-month old Friesian bulls into two types of paddocks. Those animals in paddocks where visibility was obscured by pine trees showed about one-eighth the level of aggression as those put into a bare grassy paddock. It seems likely that vision is a modifier of aggression in bulls as in some other species.

Extension agents can perform more effectively through an appreciation of individual learning styles - Paine MS (Proceedings of the New Zealand Society of Animal Production, 1993)
The levels of the A and B variant forms of

Facility design in relation to animal behaviour, stress and bruising - Grandin T (Proceedings of the New Zealand Society of Animal Production, 1993)
Animal welfare is becoming increasingly recognised as an important component of the quality assurance guarantees sought by both domestic and international consumers of primary products of animal origin. Consumers are being influenced by "conscience factors", rather than cost, and are now moving to take a "conception to consumption" interest in farming and abattoir practices and the associated animal welfare standards. Perceptions of New Zealand's welfare and husbandry practices thus play an important role in favourably positioning products in premium-priced international markets. It is important to be able to sustain, both scientifically and ethically, the New Zealand approach to animal welfare. This is especially important where New Zealand practices differ or even conflict with the practices of trading partners. In a market-responsive economy, these consumer preference trends highlight the need to present New Zealand's produce as grown in a welfare- conscious, environmentally sensitive, sustained-yield manner.

Factors affecting the production of lactose by ovine mammary cells in vitro - Davis SR; Eichler SJ; Callaghan MR; Grieve RCJ; Prosser CG (Proceedings of the New Zealand Society of Animal Production, 1993)
The present public and scientific interest in the welfare of farm livestock has caused traditional management procedures, including castration, tail docking and dehorning, to be scrutinised as causes of stress (stressors). This laudable scientific endeavour is however subject to a range of constraints. Major constraints are the subjective nature of distress, and the consequent difficulty of identifying indices which can be used confidently to quantify it. Nevertheless, behavioural and physiological indices have been identified by comparison with human responses to aversive stimuli, and allow distress to be assessed in animals. Changes in plasma cortisol concentrations, reflecting the activity of the hypothalamic-pituitary-adrenal system, are commonly used as an index of distress in farm livestock exposed to stressors. Judged thus, the distress caused by castration or tail docking of sheep and cattle apparently depends on several factors including the procedure itself, the age of the animal, the method used, the species and possibly the prior method of rearing. Little is known about the distress caused by dehorning of cattle. Several factors can confound the assessment of distress. They are: (1) balancing the objectivity of the measured indices with subjective judgements about what are acceptable and unacceptable levels of distress; (2) ensuring that the parameters used do indeed reflect distress, and not other phenomena; (3) avoiding erroneous predictions, based on anthropocentric projections and not scientific observations, about expected distress levels in situations which have not yet been examined; and (4) meeting the high cost of rigorous studies in this complex area in which a wide range of factors may affect the outcome. Reducing the distress caused by castration, tail docking or dehorning may be achieved by choosing an age when the distress response is least, choosing the least distressing method, or using anaesthesia (local, general) or systemic analgesia. When a method is identified which causes the least distress, its widespread use on farms should not be recommended unless it is also practicable. To do so will not benefit either the livestock concerned or the industry. Political and trade pressures related to overseas perceptions of New Zealand animal welfare standards require responses based on rigorous scientific assessment. Those responses are likely to involve, as appropriate, vigorous defences of current practices or the adoption of new approaches.

Farm monitoring - Review of the Northland focal farm scheme - Johnson KD (Proceedings of the New Zealand Society of Animal Production, 1993)
Genetic evaluation of dairy cattle in New Zealand is based on a system originally developed in the 1960s. Major developments in database capability and statistical techniques have taken place over the intervening years. From the mix-1980s a major redevelopment of the information and processing system for cows took place. In 1991, a major review of the sire evaluation system was initiated. A Best Linear Unbiased Prediction (BLUP) procedure has been developed based on an animal model. Implementation of a prototype system is being investigated. In contrast to the existing technique, the prototype involves a concurrent evaluation of cows and sires in all breeds using a repeatability model. This model provides breeding values for every animal (cows with one or more performance records and ancestral animals). The Livestock Improvement database has information on some 10 million animals over more than 50 years. Use of the prototype described in this paper will become routine for ranking of dairy sires from 1994 and will increase rate of genetic gain in the dairy industry by improved accuracy of evaluation and reduced bias. The improved accuracy will result from use of all known genetic relationships among animals. The current system: does not adjust the evaluation of a sire for the merit of its mates dam; ignores sons' evaluations in the evaluation of parents; ignores daughters information in the evaluation of dams. Reduced bias will result from concurrent evaluation across breeds. The current system compares animals to within-breed bases. The assumed model is identical for sires and cows in the prototype system. Furthermore, partitioning of a breeding index (BI) into its components based on information from parents, individuals and progeny is simpler than the current system which uses a recursive method for updating evaluations. Additionally, partitioning of a BI into components will provide useful diagnostic information (particularly for progeny test bulls). Interpretations of PI (production index) and BI information on reports for farmers and AB companies will be similar to the current system.

Fat colour and meat colour in different breeds of steers in five consecutive years raised on pasture and slaughtered at 30 months of age - Barton RA; Pleasants AB (Proceedings of the New Zealand Society of Animal Production, 1993)
Three experiments were carried out to determine the effects of short term nutritional changes, stress and changes in carotene content of the diet on plasma carotene concentrations (PCC) and the relative ranking of the cattle for PCC. None of the treatments affected the ranking of the cattle for PCC even though the changes in dietary carotene intake caused large changes in mean PCC.

Goals and management strategies of dairy farmers - Valentine I; Hurley EM; Glass W (Proceedings of the New Zealand Society of Animal Production, 1993)
Previous in situ hybridisation studies from our laboratory have shown that expression of certain milk protein genes is very high in some areas of the mammary glands of sheep and cattle, while in other areas containing an abundance of fat globules, it is virtually zero. We wished to determine if this heterogeneity was due to local variations in the concentrations of lactogenic hormones and/or their receptors. Artificially increasing the local concentration of lactogenic hormones in the sheep udder was attempted by inserting time release capsules containing prolactin, hydrocortisone and insulin directly into the gland up to one week before sacrifice. The local concentration of prolactin, and the milk gene expression relative to controls, appeared unchanged by the implants. The immunoreactivity of prolactin and its receptor in the mammary epithelial cell cytoplasm and in particular, the nuclei, were demonstrated and appeared to vary with the secretory activity of the cell.

Grazing management strategies for the production of fine Merino wool in North Island conditions - Litherland AJ; Haack N; Paterson DJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Twenty four, three-week old Friesian calves were fed restricted levels of milk replacer and ad libitum levels of either ensiled roughages (R) or cereal-based pellets (P). The roughage diet consisted of ensiled lucerne- molasses (Chaffhage), followed by a mixture of Chaffhage and ensiled maize-molasses (Stockhage). The calves were weaned off milk over a two week period once they reached 70 kg. Diet R calves grew significantly faster (P<0.001) and finished the trial significantly sooner (P<0.05), based on unfasted weekly liveweight data. However, no differences were observed in fasted body weight gain. Diet R was consumed in significantly (P<0.001) larger quantities and resulted in a significantly (P<0.001) greater fasting weight loss at the end of the trial. No carryover effects were observed in terms of subsequent growth rate in heifer calves at pasture following weaning. Energy digestibilities of Chaffhage and diet P (measured using 8 bull calves following weaning) were not significantly different. No carryover effects in the ability of calves reared on R or P to digest pasture were observed. It is concluded that ensiled roughage can be consumed in sufficient quantities by young calves to produce acceptable levels of liveweight gain.

Herbage allowance - intake - production relationships in continuously stocked winter- and spring-lambing ewes - Morris ST; Parker WJ; Burnham DL; Reynolds GW; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
The potential of by-products from fruit and vegetable growers and processors to serve as supplementary feeds for dairy cows in the Hawkes Bay region, which traditionally experiences poor summer pasture growth, was assessed. A total of 75 000 tonnes (wet matter) of by- products were produced by the six growers and processors surveyed, mainly between January and June. Peak by-product output occurred in April when an estimated 15,000 tonnes of wet matter was produced. Industry disposal costs ranged from $10 to $33/tonne wet matter. The metabolisable energy values (MJ ME/kg DM) of by-products were at least equivalent to those of high quality spring pasture (e.g. carrot 11.3, apple pomace 13.7), but nitrogen levels (% in DM) were low compared to those recorded in pasture (e.g. corn 1.0%, apple pomace 1.9%). A linear programming analysis of a Hawkes Bay dairy farm indicated that farmers could afford to pay up to 15.5 cents/kg DM for additional feed from May to October and 26.7 cent/s kg DM during the remainder of the year if milkfat prices were $6/kg. These shadow values indicate the maximum price that could be paid for transport and feeding costs for by-products on the model farm.

Heritability of ultrasonic fat and muscle depths in Romney sheep - McEwan JC; Clarke JN; Hickey SM; Knowler KJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Twelve buffalo (5 bulls & 7 steers) at c.33 mo of age were compared with 16 Friesian cross cattle (6 bulls & 10 steers) at c. 29 mo of age. The 2 species had not been run together, but were slaughtered and processed concurrently. Carcass weights were unaffected by species or castration (mean=258.6 kg). Relative to cattle, buffalo had shorter carcasses, higher dressing-out percentages, greater fat depths, more kidney and pelvic fat, and lower eye-muscle areas (all P<0.01). Buffalo had heavier hearts and spleens (P<0.001), and lighter livers and weights of rumen digesta (P<0.001). Buffalo rumen digesta contained fewer particles over 4.0 mm, but the size of particles in the abomasum was similar for both species. Yields of commercial cuts did not differ between buffalo and steers, but cattle steers had more fat trim, less meat, heavier striploins, and a higher ratio of hind-to forequarter meat than bulls (all P<0.05). Relative to the cattle, buffalo carcasses had lighter inside and cube roll cuts, but heavier outside flats, more fat trim, and a higher proportion of forequarter meat (all P<0.05). Buffalo fat was less yellow. Ultimate pH of cube-roll (M. longissimus) samples were higher for bulls than steers within cattle, and higher for cattle than buffalo (each P<0.05), possibly because the buffalo had been handled more. Other quality differences that could have been pH-related were the lower shear values (indicating more tender meat) and lower water-holding capacity (each P<0.01) of buffalo meat. However, colour (L*, a*, b* values), and sarcomere lengths were similar. Intramuscular fat levels were similar for meat from buffalo and cattle steers, but were much lower for bull beef. This is the first set of cattle/buffalo comparative data for carcass and meat quality collected under New Zealand conditions and will be of value when evaluating the role of Buffalo in this country.

Hormone/metabolite levels in young rams as predictors of genetic merit for backfat depth and fleeceweight - Kuhn B; Blair HT; Purchas RW; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
Three newly developed electronic lamb carcass grading probes (Hennessy Grading Probe, AUS-Meat Sheep Probe, Swedish FTC Lamb Probe) and one developmental probe (Ruakura GR lamb probe) were tested for accuracy in classifying 6 groups, each of approximately 50 lamb carcasses. They were assessed for accuracy and suitability for use on- line on the lamb dressing chain for objectively classifying lamb carcasses. Probe measurements were compared with manual GR (sometimes used at present) and Toland (can measure total tissue depth between the ribs) probe measurements for accuracy of predicting both GR on the right side of each carcass, and also carcass water (indicating muscle) and fat content. All probes combined with carcass weight accounted for over 70% of the variation (R2) of GR right with the GR left prediction accounting for 92% of the variation in GR right. The 3 commercial electronic probes used at chain speed combined with carcass weight could account for 36- 49% of the variation in % water and fat with the manual GR probe (right) doing only slightly better on the chilled carcass. Chilled carcass measurements are expected to give better results. The electronic probe results are consistent with overseas results where probes are in use for objectively grading the carcasses of meat animals.

Horse serum contains a novel insulin-like growth factor binding protein - Prosser CG; McLaren RD (Proceedings of the New Zealand Society of Animal Production, 1993)
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

How effective are exogenous progestins in mimicking the function of the corpus luteum of female cattle? - Kinder JE; Roberson MS; Kojima N; Werhman ME; Sanchez T; Cupp AS (Proceedings of the New Zealand Society of Animal Production, 1993)
Relationships were assessed between circulating concentrations of urea, creatinine, thyroxine (T4) and triiodothyronine (T3), measured at 5, 9 and 13 months of age in young Romney rams, and performance of ram's ewe progeny. Five rams were chosen at random from each of the fleeceweight- selected and control lines of a long-term selection experiment. Average performance of their progeny (n = 6 to 12 per ram) was evaluated for hogget greasy fleeceweight (adjusted for age-of-dam, birth rank, date-of-birth) and yearling ultrasonic backfat depth (adjusted as previously but also for liveweight). There was no significant relationship between progeny yearling backfat depth and sire's urea, creatinine or T4 concentration at any age of measurement of the sires. However, backfat depth of the progeny was negatively correlated with sire's circulating T3 levels at both 5 months (r = 0.76, P<0.01) and 13 months (r = -0.59, P<0.10) of age. Hogget greasy fleeceweight was negatively associated with both urea (r= -0.48 and r= -0.45, respectively at 5 and 13 months) and creatinine (r= -0.63 and r= -0.53, respectively at 5 and 13 months) concentrations in the sire at 9 and 13 months of age respectively, but only the association with creatinine concentrations was significant (P<0.05). Progeny hogget fleeceweight was positively associated with sire T3 levels at 5 months of age (r= 0.62, P<0.10) but negatively associated with sire T4 levels at both 5 months (r= -0.55, P<0.10) and 9 months (r= -0.65, P<0.05) of age. Results of this preliminary study suggest that plasma concentrations of creatinine, T3 and T4 may be worthy of more extensive investigation as potential markers of genetic merit for backfat depth and fleeceweight in sheep.

How reliable are sheep pedigrees? - Crawford AM; Tate ML; McEwan JC; Kumaramanickavel G; McEwan KM; Dodds KG; Swarbrick PA; Thomson P (Proceedings of the New Zealand Society of Animal Production, 1993)
Ligand blotting analysis of serum from the horse using radiolabelled IGF-I revealed a protein at 96 kDa which was not present in serum from goat, cow, sheep, deer or donkey. These latter species all displayed five labelled bands in the range 24 to 41 kDa. Conversely these were only weakly labelled in serum from the horse. Size exclusion chromatography of horse serum pre- incubated with radiolabelled IGF-I revealed reduced binding in the 130 kDa peak compared with goat plasma and ligand blotting analysis indicated that 96 kDa protein was present in this peak. The 96 kDa protein from horse serum binds IGF-I and IGF- II specifically and appears to be unique to this species. The nature of this protein is at present unknown.

Humane slaughter: an achievable goal? - Cook CJ; Devine CE; Maasland SA; Gilbert KV (Proceedings of the New Zealand Society of Animal Production, 1993)
Multiple anthelmintic resistance ivermectin (IVM), morantel (MOR), oxfendazole (OXF) was first demonstrated in 1988 from a goat property in New Zealand. Total spelling of all anthelmintics on the site has not been a management option. Since detection, a strict drench rotation has been adopted - levamisole (LEV) 1988-89, IVM 1990 and combination product 1991-92. IVM has been used very strategically as animal health demanded, 2 occasions in 1988, 6 in 1990 and twice in each of 1991 and 1992. In 1992 surveillance monitoring of anthelmintic status using lambs indicated that LEV remained highly effective (99.3%) against the resistant Ostertagia spp. but there was a subtle shift downward for IVM (87.5%). The alternate milbemycin, moxidectin (MOX), removed 99.9% of the Ostertagia spp. population. Stability of resistance is an important issue to address when designing and evaluating management options to delay or restrict resistance and minimise the impact on farming profitability. These results suggest that anthelmintic rotation and strategic use of IVM have not had a significant effect on the field isolate over the past 5 years. Currently in the field, there appears to be a significant difference in efficacy between IVM and MOX despite their close structural similarities. It is proposed that MOX will not be used on the site but efficacies will be monitored at regular intervals.

Impact of pre- and post-mortem factors on calpains and meat quality in lambs - Sun YX; Bickerstaffe R; Bray AR; Keeley G; Young S; O'Connell D; Mason S (Proceedings of the New Zealand Society of Animal Production, 1993)
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

Improving productivity with better stock handling - Hemsworth PH; Barnett JL; Coleman GJ (Proceedings of the New Zealand Society of Animal Production, 1993)
The ingestion of pasture with a high infection rate of endophyte may cause a variety of pathological conditions in livestock, such as ryegrass staggers, diarrhoea, hypothermia and gangrene. This experiment was designed to ascertain the function of the immune system under such conditions. Mixed age ewes were grazed during the summer months, on either high endophyte or low-endophyte ryegrass pastures. Lymphocytes were separated from peripheral blood samples by density gradient centrifugation, and subjected to an in vitro lymphocyte proliferation (lymphoblastogenesis) assay, using the mitogens phytohaemagglutinin (PHA), lipopolysaccharide (LPS), concanavalin-A (Con-A) and intestinal nematode (Trichostrongylus colubriformis) antigen. There were significant differences (P<0.05) in the response to selected mitogens, between the group grazing high versus low endophyte pasture at 14 days (PHA) and 21 days (PHA and Con-A) after the commencement of differential grazing. The animals on high endophyte pasture showed higher stimulation indices. LPS or nematode antigen had no effect on the cultured lymphocytes. As LPS is stimulatory for Bursal-derived (B) lymphocytes and PHA and Con- A for Thymic-derived (T) lymphocytes, it would appear as if material from the high endophyte pasture affected the latter cell population. It is unknown as to whether these effects on the immune system are important, in vivo.

Intake and excretion of cadmium in sheep fed fresh herbage - Grace ND; Rounce JR; Lee J (Proceedings of the New Zealand Society of Animal Production, 1993)
In two trials, ewes (n=16 per group) that were potential recipients for embryo transfer grazed on a high oestrogenic red clover (Pawera), a newly developed low oestrogenic red clover (G27) and Ryegrass-White clover (Control) pastures. The ewes grazed the respective pastures during 12 days of intravaginal sponge insertion, and for a further 23 days after induced oestrus. The mean (

Intake and liveweight change of hoggets grazing pastures differing in dead matter content in autumn - Hawkins C; Betteridge K; Costall DA; Liu Y; Vallentine I; Parker WJ (Proceedings of the New Zealand Society of Animal Production, 1993)
White clover herbage in the vegetative stage of growth has a high nutritive value for milk production, but he high crude protein content could be better utilised if cows were given a suitable readily fermentable carbohydrate source. Six rumen fistulated Friesian cows in late lactation were housed in metabolism cages and fed either fresh white clover herbage or white clover and maize silage (50:50). The experiment was a cross over design that allowed measurement of nutrient intake, rumen function and milk production. At similar digestible organic matter intakes (9.6 kg/d vs 9.9 kg/d), replacing 50% of the white clover dry matter with maize silage reduced crude protein intake by 30% (3 kg/d vs 2.1 kg/d), and urinary N excretion from 251 gN/d to 137 gN/d without affecting milk yield (12.6 l/d vs 12.51 l/d) or milk protein output (400g/d vs 413 g/d). Rumen pH was similar for both treatments (6.1 vs 6.0) but there was a higher utilisation of neutral detergent fibre (2.6 kg/d vs 3.4 kg/d) when the cows were fed the mixed diet. The excess intake of nitrogen when the cows were fed white clover only was calculated to be largely wasted as ammonia absorbed from the rumen and excreted as urinary urea.

Internal parasites and lamb production - a role for plants containing condensed tannins? - Niezen JH; Waghorn TS; Waghorn GC; Charleston WAG (Proceedings of the New Zealand Society of Animal Production, 1993)
An intensive evaluation of the hormones that are primarily involved in regulating reproductive function in cows treated with progestins was undertaken and comparisons were made to cows with a functional corpus luteum. Cows with a functional corpus luteum were found to have reduced circulating luteinizing hormone (LH) and oestradiol than cows treated with a single progesterone releasing intravaginal device (PRID), norgestomet (progestin used in Syncro-Mate-B synchrony) or melengestrol acetate (progestin used for oestrous synchrony in the USA). If greater doses of progesterone than that released from a single PRID are used, concentrations of LH and oestradiol are like those of control cows in the midliteal phase of their oestrous cycle. In addition, conception rates are significantly improved when greater doses of progesterone are used compared to that of cows in which oestrus is synchronised with a single PRID. We propose that one reason for reduced conception with oestrous synchrony programmes presently in use is the failure of the progestins to effectively mimic the function of the corpus luteum.

Introduction - Farm animal welfare contract - Matthews LR (Proceedings of the New Zealand Society of Animal Production, 1993)
Pig housing has recently been under scrutiny, resulting in some recommendations for adult pigs that may involve less individual housing. Such recommendations have obvious implications for the future viability of the pig industry. Two questions that arise are, 1) are the recommendations scientifically valid and 2) what is the likelihood of developing alternative systems? In relation to the first question, a number of experiments have been conducted on the welfare of pigs in individual and group housing systems. The overall conclusion from this research is that it is the design of the housing system that is important for welfare and not the system per se. In relation to the second question, an alternative system has been developed in The Netherlands that involves indoor group housing for pregnant and lactating pigs. Part of the system is probably directly applicable to dry sow housing in Australia and New Zealand, while the farrowing and lactation components of the system require considerable development before it is applicable to commercial environments. While there is no doubt the industry will have to change and adopt either modifications of current housing designs or totally new housing systems, past experience would indicate pig producers are fairly innovative and are very prepared to adopt new ideas that have been shown to work. It is the scientist's role to make certain that recommendations are scientifically valid and that producers are provided with the options to choose from to make their farm viable.

Investigation into the possibility of a major gene for fleece weight in screened sires - Wuliji T; Dodds KG; Fennessy PF; Andrews RN; McEwan JC; Turner P; Wheeler R; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1993)
This study investigated the effect of a progesterone containing intravaginal CIDR (Controlled Internal Drug Releasing) device on plasma progesterone and luteinizing hormone (LH) concentrations during 14-day device insertion and the subsequent oestrous cycle of fallow deer (Dama dama). Blood samples were collected from 4 entire does at 20 minute intervals for periods of 8-12h on three occasions following device insertion (i.e. insertion, mid-treatment and withdrawal) and on Days 0, 5, 12 and 19 of the subsequent oestrous cycle. Plasma was analysed for progesterone and LH concentrations by radioimmunoassay. Plasma progesterone values were elevated (>6 ng/ml) and LH values reduced (<1 ng/ml) during device insertion relative to pre-insertion values. Plasma LH concentrations were highest on Day 0 of the oestrous cycle, with a marked increase in the pulse amplitude. One doe exhibited a pre-ovulatory LH surge. Plasma progesterone increased from <0.5 ng/ml on Day 0 to 1.5-4.2 ng/ml on Day 12 (luteal phase) and high amplitude progesterone pulses were exhibited by all does on Day 19 (onset of luteolysis). The study has demonstrated that CIDR devices deliver sufficient progesterone to inhibit ovulation and the declining plasma LH concentrations during device insertion support a hypothesis of negative feedback by progesterone on LH secretion.

An investigation of sire by location interactions for faecal nematode egg counts in lambs - Morris CA; Bisset SA; Baker RL; Watson TG; Johnson DL; Wheeler M (Proceedings of the New Zealand Society of Animal Production, 1993)
The aim of this study was to gain evidence that the FecB and FecXI genes influence ovarian development in foetal life. Foetuses which were homozygous carriers of the Booroola gene (BB), Inverdale gene (II), heterozygous carriers of the Inverdale gene (I+) and non-carriers of both the Booroola (++) and Inverdale genes (++) were recovered at days 40 or 90 of gestation. To eliminate the effects of litter size in the Booroola study, equal numbers of BB and ++ embryos were transferred to recipient ewes. Subsequently no gene-specific differences in litter size were noted at the equivalent of days 40 and 90 of gestation. From these studies the FecB gene was shown to affect body weight, the weight of the mesonephros, and development of germ cells. In essence, at day 40 the mean body weight and mean weight of the mesonephros were lighter in the BB foetuses compared to the ++ animals (P<0.05). Moreover the development of the BB ovaries appeared to be retarded relative to that of the ++ ovaries with respect to mitosis and meiosis of germ cells and also the timing of germ cell atresia. In the Inverdale foetuses, which were recovered after natural matings, differences were observed at the level of the ovary but none were noted with respect to body weight, or weight of mesonephros. At day 40 of gestation the ovaries of the putative II foetuses were significantly lighter (P<0.05) than those of the I+ or control animals. Moreover at day 90 the ++ and putative II ovaries contained significantly fewer (P<0.05) germ cells (i.e. ~110,000) compared to those in the authentic or putative I+ animals (i.e. ~240,000). The differences in either the Booroola or Inverdale foetuses were not accompanied by any significant differences in plasma or pituitary concentrations of follicle-stimulating hormone or plasma inhibin. The results are consistent with the notion that the FecB and FecX genes influence ovarian development in foetal life.

Liveweight and body condition change through pregnancy as a predictor of ewe litter size - Judson HG; Nicol AM (Proceedings of the New Zealand Society of Animal Production, 1993)
Data from 95 lamb carcasses (2 data sets) and 90 bull carcasses were used to examine relationships between objective measures of carcass muscling and subjective scores of muscularity or conformation. Objective indexes calculated for lamb carcasses included muscle to bone ratios (M:B), muscularity indexes (MUSC) for both the leg and the whole side, the ratio of eye muscle depth to width (B:A), weight-adjusted eye muscle area and carcass weight per unit length. Similar variables were calculated for beef carcasses except that the weights of three commercial leg cuts were used in place of dissected muscle weights. Leg MUSC had the closest relationships with subjective scores of muscularity or conformation (R2% = 69 to 80% for lambs and 56% for bulls), with leg M:B being only slightly inferior (R2% = 62% for lambs and 652% for bulls). Side MUSC or M:B were the next best as predictors, but variables based on the eye muscle were poor. Carcass weight per unit length showed close relationships with subjective scores in some cases but its usefulness is limited by the fact that it can be influenced by fatness and is breed related. These results support the contention that measures of M:B may not always reflect muscularity scores because they are based on weights rather than depths and lengths. It is concluded that the objective measures of MUSC used here reflect subjective scores satisfactorily, given that subjective scores have limitations with respect to repeatability. MUSC based on the femur and the muscles or cuts surrounding it, in particular, may constitute a useful objective standard for use in the industry.

Liveweight, feed intake and feed conversion efficiency of lactating dairy cows - Holmes CW; Wilson GF; Kuperus W; Buvaneshwa S; Wickham B (Proceedings of the New Zealand Society of Animal Production, 1993)
A method was developed to isolate mammary cell clumps (acini), from lactating sheep and maintain these in culture for more than 48 h. Performance of these cells was assessed by the measurement of lactose secreted into media using a sensitive bioluminescence assay. Lactose production was dependent upon cell density at seeding, lactose output per cell being 5-6 fold higher (6-7 fmol/cell/h) at 0.25x10 6 cells per ml medium compared to 2.5x10 6 cells per ml medium over 24 h of culture. Lactose output declined with time in culture, irrespective of cell density, falling to <1 fmol/cell/h over the period 24-48 h. 2-deoxy glucose uptake by mammary cells tended to increase with time in culture. 2-deoxy glucose uptake was significantly higher in cells from starved sheep (p<0.05) and in cells cultured in medium containing foetal calf serum, insulin, hydrocortisone, prolactin and prostaglandin E2 (p<0.001). Lactose output of acini was not affected by starvation of the ewe for 18 h before removing mammary tissue, and increased slightly (11%) at low cell density in response to the additions of hormones and/or foetal calf serum to culture medium (p<0.05).

Measurement of relative levels of radioactivity in labelled tissue sections using image analysis - Ord R; Hodges A; Nixon A; Molenaar A; Dobbie P; Kirk S (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied

Metabolic changes in sheep divergently selected for plasma IGF-1 - Sherlock RG; Blair HT; Kuhn B; MacKenzie DDS; Breier BH; Gluckman PD; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
The detection of small amounts of biologically active material in animals may require quantification of radioactive label. Here we compare several image analysis methods for quantifying relative levels of radioactive probe detected by x-ray film or photographic emulsion. Total RNA "dot blots" and ovine muscle sections were probed for the presence of muscle actin mRNA using 35S-labelled riboprobes. Bound probe was detected by x-ray film in both cases. The probed sections were further exposed to photographic emulsion, while the dot blots were individually quantified by scintillation counting. Bound probe was quantified macroscopically by digitisation of optical density (OD) and thresholding of the x-ray film image. Dot blot image ODs were correlated with scintillation counts (r>0.96), demonstrating that the levels of mRNA detected in tissues by autoradiography are proportional to cellular mRNA concentration. Densitometry of section macroautoradiographic images can therefore be useful in determining relative probe signal at the tissue level. When probe was quantified microscopically by counting silver grains in emulsion autoradiographs, simple thresholding correlated with manual counts (r=0.88) but was unreliable at higher grain densities. Processing of the gray image gave a more direct estimate of silver grain density (r= 0.98).

Milk Production and Production Index Comparisons in Mixed Breed Dairy Herds - Glassey CB; McPherson JR (Proceedings of the New Zealand Society of Animal Production, 1993)
Liveweight, milk yield and feed intake were measured in two experiments, the first with 30 cows grazing on pasture and the second with 16 cows fed indoors on fresh pasture. Feed intakes by the grazing cows were estimated from faecal outputs, using chronic oxide as the indigestible marker. The relation between daily metabolisable energy intake (MEI), daily milk energy output, liveweight 0.75 (LW0.75) and daily change in liveweight were examined by multiple regression analysis. Milk energy was significantly related to MEI, and therefore (at a common milk energy output) on feed conversion efficiency. An "index of efficiency" is proposed which will enable cows which differ in milk yield, weight and breed to be ranked accordingly to their predicted "gross feed conversion efficiency".

Oestrus, ovarian activity and embryo survival in ewes grazing high and low oestrogenic red clover - Anwar M; Keogh RG; McDonald MF (Proceedings of the New Zealand Society of Animal Production, 1993)
Seasonal wool growth pattern, colour variation and associated wool characteristics were measured in a fleece weight selected (HFW) and its control (RC) flocks. Both flocks had a significant (p<0.01) decline in wool growth rate in winter compared with summer. The HFW advantage over RC averaged 19% and 33% for ewes, 24% and 36% for hoggets, in summer and winter respectively. Yield and fibre diameter patterns were closely associated with wool growth. There were no flock differences in either brightness or yellowness, however both Y and Z tritimulus values were lower in spring and summer while yellowness was higher in summer than other seasons. The results suggest that selection for HFW reduces the relative winter wool growth decline compared with RC.

Ovine IGF Antisense RNAs? - Ord R; Ledgard A; Berg D; Peterson J (Proceedings of the New Zealand Society of Animal Production, 1993)
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 CIDR

Pasture protein and soluble carbohydrate levels in spring dairy pasture and associations with cow performance - Moller S; Matthew C; Wilson GF (Proceedings of the New Zealand Society of Animal Production, 1993)
A survey on the East Coast of the North Island was conducted to provide information on the on-farm performance of drought tolerant pastures, including perceptions on animal toxicity problems. During October- December 1990 over 250 paddocks on 102 sheep/beef farms in Gisborne (23, Hawkes Bay (32) and the Wairarapa (47) were surveyed. Botanical composition was measured for each survey paddock from turf cores. No animal health problems were reported for prairie grass pastures, but farmers commented on improved animal performance from this pasture type. Animal health problems mentioned by farmers surveyed were: (1) ryegrass staggers, being reported for 58% of survey farms and 9% of survey paddocks. Ryegrass staggers was usually mentioned for paddocks with a high perennial ryegrass content (>40% cores containing ryegrass). It was mentioned less frequently for mixed ryegrass- cocksfoot swards (>40% ryegrass, >10% cocksfoot) than for swards containing similar levels of ryegrass but little cocksfoot. (2) Bloat was mentioned more frequently for paddocks sown with tall fescue (15%) than for other pasture types (3%). Tall fescue swards had a higher clover content than ryegrass swards. (3) Stock ill-thrift (low growth rate) was mentioned for 6 of the 260 survey paddocks. The common feature of these paddocks was a moderate to high cocksfoot content (21- 72% cores containing cocksfoot). (4) Phalaris toxicity was mentioned by 18% of farmers who had phalaris pastures.

Plasma concentrations of progesterone and luteinizing hormone during CIDR device insertion and the oestrous cycle of fallow deer (Dama dama) - Morrow CJ; Asher GW; Smith JF; Veldhuizen FA (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

Plasma prolactin in Romney sheep selected for hogget fleece weight - Clarke JN; Pearson AJ; Sumner RMW; Johnson DL; Dobbie JL; Wildermoth JE; Wrigglesworth AL (Proceedings of the New Zealand Society of Animal Production, 1993)
Seventy nine mature, alpacas were scanned every 10-14 days using real time ultrasonography to visualise the foetus. There was a 24% foetal loss between days 21-30 of gestation and parturition, with the maximum loss occurring between days 21-30 and days 31-40 of gestation. There was a 5% loss of foetuses after day 100 of gestation.

The potential of industry by-products as supplementary feeds for dairy cows in the Hawkes Bay region - Bramwell NF; Parker WJ; Gray DI; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied.

Prediction in animal production models based on the allometric hypothesis when the size variable is random - Pleasants AB; Wake GC; Rae AL (Proceedings of the New Zealand Society of Animal Production, 1993)

Presidential Address 1993 - The Management of Science - Wallace RD (Proceedings of the New Zealand Society of Animal Production, 1993)
Jersey cows in six mixed breed dairy herds produced up to $0.36 per cow per day less than their Friesian herd mates, during the 1991/92 dairy season. Jersey cows received lower Production Indexes (PI's) than their Friesian and Crossbred herd mates. It is not clear whether this lower production of Jersey's is a result of competition for feed between breed groups or is a genuine genetic difference between breeds. Some of the difference can be explained by the lower protein to fat ratio of Jersey milk compared to Friesian milk. Jersey cows are more efficient producers of milk income per kg liveweight than Friesians. If the breed composition of a herd is changing towards Friesians or Crossbred, then stocking rate as measured by liveweight per ha will also increase. Where stocking rate is already high this will inevitably reduce pasture intake of individual cows unless pasture supply is increased. Farmers would like to know if the Jersey component of their herds can be managed to improve production relative to Friesian or whether changes in breed composition of their herds are necessary to achieve optimum production and herd size in relation to feed supply and other farm resources.

A prototype sire evaluation for New Zealand dairy cattle - Garrick DJ; Harris BL; Shannon P; Sosa-Ferreyra C (Proceedings of the New Zealand Society of Animal Production, 1993)
Growth of mammary epithelium is regulated by endocrine signals, local factors and sensitivity of epithelial cells to mitogens and inhibitors. This study was designed to identify how these factors interact in regulating mammogenesis and determine if breed differences exist among these factors. Mammary epithelial cell organoids were isolated from five pairs of beef and dairy heifers (7 to 9 months of age) and cultured within collagen gels. Sera were collected from all heifers and pooled within breed for use in culture. At slaughter, explants of mammary fat pad were also prepared for culture. Culture treatments were arranged in a 2x2x3x4 factorial design. Factors included source of cells (beef or dairy), addition of growth factors (10 ng/ml IGF-I + 50 ng/ml EGF or control), source of mammary fat pad explants (beef, dairy or none) and source of serum added to culture media at 5% final concentration (beef, dairy, foetal calf serum, or none). Mammary growth was assessed as incorporation of [3H]thymidine into DNA. Mammary epithelial cells from beef heifers grew more rapidly than dairy cells (2518 vs 1192) cpm/ug; P<0.01). Growth of epithelia was enhanced by addition of growth factors (2265 vs 1445 cpm/ug; P<0.01). Sera from both beef and dairy heifers stimulated growth 2-fold compared to no serum (P<0.01), but addition of mammary fat inhibited epithelial growth (P<0.05). Cells from beef heifers were also more responsive to addition of serum and growth factors. These findings demonstrate that multiple factors interact to control mammary growth. Mammary fat pad of ruminants, unlike rodents, appears to inhibit epithelial growth.

Rate of intake by sheep of different genotypes of subterranean clover in the vegetative growth stage - Dynes RA; Baker SK; Purser DB; Klein L; Wang XR (Proceedings of the New Zealand Society of Animal Production, 1993)
Consulting Officer survey data from 198 owner/operator dairy farms for the 1991/92 season was analyzed. Trends in income, farm costs and profitability at changing levels of milkfat production/ha were examined. Increases in milkfat production/ha were associated with increases in stocking rate (R

Regulation of growth in cultured mammary epithelium from beef and dairy heifers - McFadden TB; Cockrell DC (Proceedings of the New Zealand Society of Animal Production, 1993)
Red deer have recently been introduced to the intensive domestic environment, where there are many social and physical constraints not experienced by wild deer. Aspects of the social environment likely to affect welfare include group size, density and composition. Physical aspects of the pasture environment which may influence welfare are shade, shelter, wallows and opportunities for ranging behaviour, while variables in the handling environment which are probably important are pen construction and lighting. Various methods have been employed to assess welfare in red deer. Studies of confined deer have indicated that they respond to aversive conditions at pasture by pacing along fencelines, and in the handling environment by nosing doors and walls. Preference testing has compared different handling environments and treatments, and demonstrated that human presence, novelty and mechanical restraint were aversive. Results from detailed studies of velvet antler removal suggest that improved methods of providing analgesia are possible. Research into modifying the basic character of farmed deer through genetic selection or intensive handling of deer calves has been instigated. Overall, high welfare standards in deer production systems are a realistic goal. There are no long-established traditions to adhere to, and a foundation of productive assessment techniques and results has been established.

The relationship between breeding index and conception rate and the cost of delayed conception - Wheadon MC (Proceedings of the New Zealand Society of Animal Production, 1993)
Programmes for controlled calving and controlled breeding were evaluated with a group of large herds of dairy cows and heifers. The former procedure involved an injection of an analogue of prostaglandin F2a (PGF) at about Day 274 of gestation. Groups totalling 650 cows mainly calved in the following 4 days, with a peak between 36 to 60 h. The maximum calving rate was 138 cows within one 24 h period. Although calf survival rate was high (97%) and the incidence of calving difficulties low (3%), 14 cows were subsequently culled because of complications caused by retained foetal membranes. The controlled breeding programmes involved the use of CIDR-B devices for 8 days (cows) or 10 days (heifers) combined with a capsule containing 10 mg of oestradiol benzoate at device insertion (all cows and heifers), and with an injection of PGF at 6 days after insertion (cycling cows and all heifers), or an injection of equine chorionic gonadotrophin (eCG) at device removal (anoestrous cows). These systems were used with herds of 3009 and 500 heifers, as well as with 350, 400, 480 and 904 lactating cows. Every heifer was inseminated initially at about 48 h after device removal, but cows were inseminated on detection over 4 days. All inseminated animals were retreated with a previously used CIDR device to re-synchronise oestrus before a second insemination about 21 days later. A second re-synchrony was also applied with some cows before their third insemination. These programmes produced 4-day submission rates in the cows of 87% to 95% and 48 h synchrony rates of 94% and 95% in the heifers. The consequences of these programmes mean that about 90% of animals in each herd will have conceived to AB or natural mating within 6 weeks. The rate of use of induced calving next season should be reduced to about 5%. The increased concentration in calving is expected to reduce the incidence of treatments for anoestrum (from as high as 44% in one of the herds) to about 10%. Additional advantages include time saving, less labour, reduced labour stress, more cows and heifers to calf to AB sires, fewer bulls and earlier culling of bulls and empty cows. The maximum daily numbers were 904 CIDR devices inserted in 5 h, 504 heifers inseminated in 4 h and 689 cows inseminated in 5 h. Whereas calving and breeding had previously been major constraints in herd management, the use of these systems can realistically allow the herd size to be increased to more than 1000 cows. Many of the identified advantages will be equally applicable to herds of less than 200 cows.

The relationship between milkfat production per hectare and economic farm surplus on New Zealand dairy farms - Deane TH (Proceedings of the New Zealand Society of Animal Production, 1993)
Dairy cows are in negative energy balance in the early postpartum period. It was hypothesised that cows that had not resumed ovulating by 1 week before the planned start of mating (PSM) were in negative energy for a longer period and/or to a greater depth than cycling cows. This case-control study compared the condition score, concentrations of selected blood metabolites and milk production in each of 90 pairs of anoestrous and cycling dairy cows on 8 farms. Anoestrous cows had a lower condition score (0.3 units), a higher urea concentration (0.3 mmol/l) and a lower glucose concentration (0.11 mmol/l) than their cycling pair. There was no difference in milk volume, milk fat, protein or length of lactation between cycling and anoestrous cows. The hypothesis that anoestrous cows are in lower energy balance than cycling cows is supported.

The relationship between staggers and diarrhoea in lambs grazing different components of endophyte-infected ryegrass - Pownall DB; Lucas RJ; Familton AS; Love BG; Hines SE; Fletcher LR (Proceedings of the New Zealand Society of Animal Production, 1993)
Two experiments were carried out to measure the effects of fitting polyethylene body covers on the winter milk production of mature cows, and oxygen consumption by calves. In the first experiment, the covers had no significant effects on the winter milk production or liveweight of lactating cows grazing on pasture supplemented with silage. In the second experiment, oxygen consumption by young calves exposed to an air temperature of 9 C, 8 km/hour wind and simulated rain was significantly reduced by the wearing of covers (by 40% during the period of rain). Covers offer an effective, low- cost method for reducing the adverse effect of cold wet weather on young calves reared out-of-doors.

Relationships between loose wool bulk and follicle and fibre characteristics in yearling Perendale sheep - Sumner RMW; Stobart RH; Johnson DL (Proceedings of the New Zealand Society of Animal Production, 1993)
Progeny test mating was carried out for 7 high fleece weight (HFW) and 5 random control (RC) sires from the Woodlands breeding flocks in 1987, and for a 4 HFW sires in 1988. In 1990, 8 of the surviving HFW sires were backcross mated to their daughters (born in 1987 and 1988). There was no evidence for any of these sires being heterozygous, or for any of the sires involved in the backcross being homozygous, for a major gene which affects either fleece weight or liveweight.

Relationships between objective and subjective measurements of carcass muscularity - Abdullah AY; Purchas RW; Davies AS; Kirton AH (Proceedings of the New Zealand Society of Animal Production, 1993)
No abstract supplied

Repeatability estimates and selection flock effects for faecal nematode egg counts in Romney breeding ewes - Morris CA; Watson TG; Baker RL; Hurford AP; Hosking BC (Proceedings of the New Zealand Society of Animal Production, 1993)
The effect of melatonin (Regulin

Seasonal and between sheep differences in medullation of wool fibres - Scobie DR; Woods JL; Baird DB (Proceedings of the New Zealand Society of Animal Production, 1993)
Two experimental flocks of Romney sheep selected for increased hogget fleece weight show high selection responses (30-40% of their controls) and evidence for altered seasonal patterns of annual wool growth, in line with published evidence from other flocks. While a preliminary experiment was unable to detect consistently significant line differences in plasma prolactin concentration at set time periods, there were indications of altered seasonal patterns in prolactin concentration and line differences in its association with wool growth. Both selection and control lines showed low prolactin concentrations in June and July (16 ng/ml). Concentrations rose in August, September and October, approximately doubling each month to an average level of 111 ng/ml in early November. Early results from this longitudinal study, still in progress, suggest that animals from the selected lines tended to maintain their low prolactin concentrations longer into the winter and early spring, and that this tendency is associated with a higher hogget fleece weight. By contrast, in the unselected control lines, high hogget fleece weight tended to be positively associated with increasing prolactin levels over the winter/early spring period.

Seasonal fibre growth patterns in three breeds of down goat - O'Neill KT; Litherland AJ; Spring PJ; Paterson DJ (Proceedings of the New Zealand Society of Animal Production, 1993)
Subcutaneous fat colour at slaughter, after chilling for 24 hours was subjectively assessed on a scale of 1 (very white) to 5 hours (very yellow). Beef breeds (Angus, Beef Shorthorn, Galloway, Hereford and Red Poll), and dairy breeds (Friesian, Milking Shorthorn, Ayrshire and Jersey) of steer were slaughtered at 30 months of age over 5 consecutive years. The Friesian and Angus breeds were present every year and other breeds except for the Hereford and Red Poll were present for at least 2 years. The beef breeds had significantly (P<0.01) more carcasses with white fat than the dairy breeds. The Beef Shorthorn had significantly (P<0.05) more carcasses with white fat than the Angus. The Ayrshire had more carcasses with white fat (P<0.01) than the other dairy breeds. The Jersey had more carcasses (P<0.05) with yellow fat than all the other breeds. For the dairy breeds only there were significant correlations (0.4 - 0.7) between fat colour after chilling and the weight of kidney and channel fat. The more kidney and channel fat present the yellower the carcass. There was a correlation of 0.32 between meat colour and fat colour after slaughter. Friesian steers had more carcasses (P<0.01) with dark red meat than did the other breeds.

Selecting on pubertal traits to increase beef cow reproduction - Morris CA; Bennett GL; Johnson DL (Proceedings of the New Zealand Society of Animal Production, 1993)
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

Selection programmes for nematode resistant sheep in commercial flocks - Watson TG; Hosking BC; Johnson DL; Hurford AP (Proceedings of the New Zealand Society of Animal Production, 1993)
An experiment was established at Waikeria, near Te Awamutu, to select for pubertal traits in Angus cattle, with selection first applied to the animals born in 1982. The aims of this paper are to report on genetic parameters for age at first oestrus (AFO) in heifers, weight at first oestrus (WFO) in heifers, scrotal circumference (SC), 13-month weight (W13) and calving day (CD), to compare the performance of young animals in the selection and control herds, and to assess prospects of achieving a correlated response in calving rate. Three selection herds and a control were set up, with single selection objectives being SC, AGE+ and AGE-, where '+' and '-' indicate selection for greater or lesser AFO. Phenotypic coefficients of variation were 15% for AFO, 11% for WFO, 8% for SC, and 8% for W13. Corresponding heritability estimates from Waikeria were 0.15, 0.30, 0.24 and 0.33, compared with those from other New Zealand research herds which averaged 0.34, 0.37, 0.38 and 0.36 respectively. The genetic correlation estimate for AFO and SC was - 0.81

Serum concentrations of insulin-like growth factor-I during the oestrous cycle in ewes selected for lamb production - McFadden TB; Stellflug JA; Cockrell DC; Butler JE (Proceedings of the New Zealand Society of Animal Production, 1993)
In keeping with the evident requirement of insulin-like growth factor I (IGF-I) for normal growth in livestock, IGF-I is required for the normal proliferation of many non-transformed cells in tissue culture. The timing of IGF-I action is believed to be early in proliferation and/or prior to DNA synthesis. Since IGF-I acts on the Type I and Type II IGF receptors, and on the insulin receptor, it is possible that one or all of these receptors are proliferation regulated, such that they are expressed mainly at a certain stage(s) in the cell proliferation cycle. Regulation might occur at the level of the receptor or at the mRNA level. Several cell types have been chosen to test this model. In the experiments reported here, Norden Lab Feline Kidney (NLFK) cells were grown on coverslips and synchronised using a starve/feed regimen. Coverslips fixed at various times after refeeding were probed in situ for the presence of actin RNA and for IGF Type I receptor RNA. Whereas actin RNA levels increased and declined during the proliferation cycle in agreement with earlier reports. Type I receptor RNA levels were undetectable at the times sampled. Possible reasons for this are discussed.

Short term changes in selected metabolites in pasture fed dairy cows during peak lactation - Kolver ES; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1993)
Computer-based decision support systems could provide an effective mechanism to facilitate technology transfer to farmers, and also improve the quality of their management decisions. The developers of computer systems, therefore, need to be cognisant of the constraints faced by farmers and the management methods that they use. To assist with the development of an expert system for the drying off decision a mail survey of 250 seasonal supply dairy farmers in five regions of New Zealand was undertaken during the 1992 winter to obtain information on management practices and decision aids used on farms. A response rate of 70% was achieved. Most (69%) farmers dried off some cows before drying off the main herd on the basis of age and condition. Final drying off date was most often based on pasture availability, cow conditions and/or the availability of supplements (85%). Mean pasture cover targets at drying off ranged from 1606 kg DM/ha in Northland to 2129 kg DM/ha in South Taranaki. Most farmers expected pasture cover to increase between drying off and calving. Only 22% of the farmers formally prepared a feed budget. A condition score target at drying off was given by 56% of the respondents (of which only 40% used a 1-10 scale). Computers were owned by 19% of the surveyed farmers. Inexperience with computers (60%), the cost of hardware (40%), lack of time to learn how to use computers (34%), no interest in computers (27%) and the belief that computers could not help management (27%) were cited as reasons for not owning a computer. The survey results indicate that computer-based decision support systems should be targeted initially at consultants who could provide a "bureau" type service to individual farmers. The present low level of formal feed budgeting limits the utility of decision-support systems that require objective farm data for developing grazing management recommendations.

Skin follicle development in South African (SA) and SA x New Zealand Angora goats - Parry AL; Death AF; Dick HB; Miller CM; Craven AJ (Proceedings of the New Zealand Society of Animal Production, 1993)
The expected value of the solution of the differential equation arising from the allometric hypothesis when the variables are random is found. This solution differs from the deterministic solution, so that predictions using the allometric equation which ignore the stochastic nature of the differential equation are biased. When lease squares estimation is carried out using the deterministic solution, ignoring the stochastic nature of the size variable, the estimate of the constant coefficient of the allometric equation may be severely biased. An example shows mild bias in estimates of the maturity parameter, but large bias in the estimate of the constant coefficient. To obtain unbiased estimates of the parameters in the allometric equation a factor equal to the reciprocal of the square of the size variable must be added to the usual log-log regression used to calculate estimates of the parameters. These results have application to models based on the allometric hypothesis, in particular models which are used in studies of carcass composition and the description of maintenance requirements in animal nutrition. When these models are used for prediction they need to be modified to account for any random variation occurring in the size variable.

Stability of invermectin resistance in a field strain of Ostergagia spp - Watson TG; Hosking BC; McKee PF (Proceedings of the New Zealand Society of Animal Production, 1993)
This study was undertaken to investigate the effects of time from CIDR withdrawal and ewe age on conception rates in a sheep artificial insemination programme. Four groups each of 50 Romney ewes (balanced for ewe age, two-tooths vs mixed age) were synchronised by intravaginal insertion of CIDRs for 11 days. Ewes in each group were inseminated at 36h, 42h, 48h or 54h respectively from CIDR withdrawal by cervical insemination using 200 million sperm per insemination of fresh semen. Conception was determined by measuring non-return rates using harnessed rams. Conception rates increased (P<0.10) with the interval between CIDR withdrawal and fixed time insemination thus: 36h, 37%; 42h, 49%; 48h, 59%; and 54h, 60%. Conception rates were greater in mixed age ewes (58%) than in two tooth ewes (43%) (P<0.05). There was no interaction between the effects of age and time of insemination relative to CIDR withdrawal. It is concluded that there may be advantages in extending the interval between CIDR withdrawal and insemination to 48 to 54 h as opposed to the current industry recommendations of 45 to 48 hours.

Studies of alternative selection policies for the New Zealand sport horse - Rogers CW; Wickham GA (Proceedings of the New Zealand Society of Animal Production, 1993)
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.

Textile Evaluation of Texel Wools - Maddever DC; Wuliji T (Proceedings of the New Zealand Society of Animal Production, 1993)
Evidence for multiple anthelmintic resistance has emerged rapidly. The need to investigate innovative alternatives to maximise nematode control is significantly more critical. Selection of sheep with above average natural or acquired resistance to infection is one such option that is being studied. Progeny testing for faecal nematode egg count (FEC) has been evaluated following natural infection. Research involving 104 sires used on 4 commercial Romney studies over the last 2-5 years demonstrated considerable genetic variation. Heritability estimates for FEC ranged from 0.17 to 0.27. Moderate to strong positive genetic correlations (0.38-0.75) between FEC1 and FEC2 were observed. Furthermore, genetic correlations between FEC1 or FEC2 and production traits, including weaning weight, later liveweights and fleece weight were moderate. Breeders face a philosophical dilemma whether to become involved in selection for nematode resistance or not in the face of the many unanswered questions, including why and how to undertake the work. Results to date indicate that breeders can adopt and apply a screening protocol to add to breeding trait records.

Twinning in beef cows: preliminary results from embryo transfer studies - McMillan WH; Hall DRH; Evans PH; Day AM (Proceedings of the New Zealand Society of Animal Production, 1993)
While the main focus in the breeding of Texel sheep in New Zealand has been selection for superior meat production there are significant qualities in the wool which make it a highly desirable fibre. Texel, Texel X Romney and Romney wools are evaluated to determine their relative attributes as textile fibres in wool products where good length and high bulk are considered important. Evaluation involved examining the value of good length bulk wool in the current wool market, spinning semi-worsted yarns, manufacturing carpets and sample bedding products. All three lines performed as expected from the measured fibre characteristics. Core bulk of the scoured wool for Texel, Texel X Romney and the Romney were respectively 32.9 cm3/g, 29 cm3/g and 25.7 cm3/g. Based on an average market value of 450 c/kg clean and 1991/92 relativities, the premium for bulk of these long good colour wools is 10 c/kg/unit. The high bulk wools gave improved spinning performance 44.4 52.9 and 73.3 end breaks per 100 spindle hours at 5000-6000 rpm for the Texel, Texel X Romney and Romney lines respectively. Improved abrasion resistance of carpet made from the Texel and Texel-cross was attributable to different pile weight and yarn bulk values. Samples evaluated indicate Texel sheep produce wools with similar textile properties to New Zealand crossbred wools but with higher bulk. The Texel breed should be monitored for its suitability as a source of genetic material to increase bulk in New Zealand wools. Lack of quantitative knowledge of the change in fleece weight and carcass returns from the introduction of the Texel genetic influence into Romney stock prevents assessment of their economic benefit to the New Zealand farmer.

Twin-suckling beef cows using foster calves: effects on cow and calf performance - McMillan WH; Evans PH; Hall DRH; McLean M (Proceedings of the New Zealand Society of Animal Production, 1993)
One hundred and twenty three Friesian or Friesian x Jersey mature dairy cows were used to examine the effects of Rumensin Anti- bloat Capsules (ABC), containing sodium monesin on plasma magnesium, glucose and

The use of commercial grading probes for classifying lamb carcasses - Kirton AH; Mercer GJK; Duganzich DM; Uljee AE (Proceedings of the New Zealand Society of Animal Production, 1993)
North American wapiti (Cervus elaphus sub species)_ evolved within, and inhabit, an extremely varied environment generally not apparent within any pastoral farm environment. Normal farm management practices also reduce disease and predation; modify or prevent behavioral strategies such as migration, wallowing and isolation at calving; impose artificial mate selection; result in the removal of antlers in velvet, and premature dissociation of familial groups. Whilst the object of these practices is to utilise deer for animal production, primarily meat and velvet antler, the vast changes imposed will undoubtedly result in rapid changes in genetic, physiological, morphological and behavioral characteristics of the animals. Deer provide a unique opportunity to study and manipulate the effects of farming in a large ruminant, but at the same time the ecological requirements of the animal should be considered.

Utilisation of white clover pasture and maize silage by the lactating dairy cow - Wanjaiya GW; Wales WJ; Dellow DW (Proceedings of the New Zealand Society of Animal Production, 1993)
A survey of 110 beef cattle farmers within Waitomo Country was used to identify the main farm and farmer factors associated with adoption of three beef cow technologies. It was found that 48% of farmers had adopted mating of heifers to calve at two years of age; 43% had adopted breeding from dairy beef crossbred cows; and 60% were using terminal beef breeding bulls. Overall, 30% of the farmers had adopted none of the technologies; 20% had adopted one of the technologies; 25% had adopted all three of the technologies. The levels of adoption were higher than those expected from national statistics. An assessment was made of the relationship of demographic indicators with technology adoption. Farmers' age, education and sources of information were associated with technology uptake. A number of business indicators were included in the survey. Gross farm income, farm expenditure, stocking rate, paddock number, stock weighing, were found to be associated with adoption of at least one of the technologies. The beliefs that farmers had about their core enterprise - beef breeding cows, was found to be closely associated with their adoption decisions. It is shown that evaluation of new technologies in relation to the core enterprise beliefs held by individual farmers should be included when considering research programmes of potential value to the industry.

Variability in the susceptibility of wool to yellowing - Reid TC (Proceedings of the New Zealand Society of Animal Production, 1993)
The advent of highly polymorphic genetic markers in sheep has enabled, for the first time, a retrospective study of the pedigree records of New Zealand sheep flocks. Three research flocks and one study flock have been analysed. The flocks were genotyped using a variety of microsatellite DNA markers and/or the polymorphic blood proteins transferrin, vitamin D binding protein, and ovine plasminogen antigen. The first flocks analysed were the half-sib Booroola pedigrees from progeny tests of heterozygous Booroola rams and their daughters. Of 291 daughters of rams, 7 were shown to have an incorrect sire assignment. The remaining flocks consisted of full sire/dam/offspring pedigrees. The stud flock showed 2 instances in 45 pedigrees where the sire was incorrectly assigned. Of 53 Inverdale lambs tested 5 were shown to have an incorrectly assigned parent and in 387 pedigrees from a progeny test flock at Woodlands only two pedigree errors were detected. These error rates are lower than previously estimated from field observations which give confidence in the use of these pedigrees for genetic selection. Simple flock management techniques are described which help achieve the low error rates reported.

Vasodilatory properties of parathyroid hormone-related protein in the mammary gland of the lactating goat - Prosser CG; Davis SR; Farr VC (Proceedings of the New Zealand Society of Animal Production, 1993)
New Zealand dairy systems are characterised by extensively- managed outdoor herds which calve in spring. Such systems allow cattle to perform a wider range of normal behaviours than is possible in more intensive conditions. However, there are aspects of extensive management which may compromise the welfare of dairy cattle. These include practices which are intrinsic to the management system and strategic interventions. This paper will discuss some of the issues pertaining to the welfare of dairy cattle, the methods by which welfare is assessed and attitudes within the local and international community regarding the management of dairy cattle in New Zealand.

Is the welfare of dairy cows at risk from current farm practices? - Hargreaves AL; Matthews LR; Verkerk GA (Proceedings of the New Zealand Society of Animal Production, 1993)
A selection experiment to breed for high (H), control (C) or low (L) faecal egg count (FEC) levels in weaned Romney lambs was established in 1985, being maintained at Rotomahana (until weaning 1988) and at Tokanui thereafter. In winter 1990, pregnant ewes (aged 2 to 6 years) were drafted into grazing groups according to expected lambing date ('early' and 'late' ewes), in order to study periparturient FEC. Non- pregnant ewes and unmated yearling females were also recorded. Faecal samples for FEC were taken from all females (n=253) before and after the pregnant ewes lambed (median lambing dates for early and late ewes being 19 August and 31 August), and then in October and in November. Lambs were also faecal sampled at 3-month weaning. A mixed model was fitted to log e (FEC + 100), with fixed effects for selection flock, group (early ewes, late ewes, non- pregnant ewes, yearlings), sample day and the interaction of group and day, and with 'animal' as a random effect. The repeatability was 0.50

The welfare status of egg-production in New Zealand - Temple W; Foster TM (Proceedings of the New Zealand Society of Animal Production, 1993)
During the springs of 1990 and 1991 128 recipient cows were artificially inseminated (AI) and 7 days later one embryo was transferred (ET) to induce twinning. Twenty-six per cent (33/128) of recipients returned to oestrus within 25 days of AI. Pregnancy diagnosis at 35 days indicated 12%, 39% and 23% of recipients with 0, 1 or 2 foetuses. The expected calving rate was 63% of which 38% were expected to twin. Only 43% calved but 50% gave birth to twins. The results were similar in both years. These results indicate that the combination of AI and ET result in normal pregnancy rates and higher than expected twin pregnancy rates at about five weeks after AI. However, losses from five weeks to calving are several times higher than expected, and are a major limitation to the achievement of 100% plus calving to one round of treatment. Early pregnancy diagnosis (day 35) may have precipitated such losses.

What might be the consequences of adapting wild animals, such as wapiti, to a farm environment? - Fisher MW; Bryant LD (Proceedings of the New Zealand Society of Animal Production, 1993)

Wool growth responses of Romney rams selected for high or low wool strength to nutrient supplementation in winter - Bray AR; Smith MC; Merrick NC (Proceedings of the New Zealand Society of Animal Production, 1993)
Treatment of sheep, mice and humans with exogenous recombinantly- derived insulin-like growth factor-1 (IGF-1) has been reported to produce a hyperglycaemic state. In mice this is associated with the abolition of maternal constraint during pregnancy. Exogenous IGF-1 also alters renal clearance in sheep and humans, decreasing circulating concentrations of urea and creatinine. The objective of this study was to determine whether similar changes are apparent in sheep divergently selected for plasma IGF-1 concentrations. Ewe hoggets (10 months old), 16 each from the Massey University Low (L), Control (C) and High (H) IGF-1 selection lines, were blood sampled by jugular venipuncture over a 5 hour period after removal from pasture. Plasma metabolite concentrations were assayed and adjusted for the effects of sampling time relative to removal from pasture. There were no differences between the line (L vs C vs H) in plasma concentrations of urea (7.34 vs 7.35 vs 7.32 mM, Pooled SE = 0.25 mM) and, although there was a significant line effect for creatinine (P<0.05), none of the between-line comparisons was significant (0.073 vs 0.075 vs 0.075 mM, Pooled Se = 0.002 mM). However, glucose concentrations were greatest in the H line (3.72 mM), followed by the C line (3.56 mM) and the L line (3.45 mM) (PSE = 0.07 mM, P<0.05). Whereas glucose and urea concentrations declined with time off pasture in the H line (b = -0.133

Advancing calving in red deer: The effects on growth and sexual development - Meikle LM; Fennessy PF; Fisher MW; Patene HJ (Proceedings of the New Zealand Society of Animal Production, 1992)
Thirty ewe lambs each of Merino, Romney, feral (of Merino origin) and Wiltshire breeds were evaluated for dag score, flystrike and nematode resistance. The lambs were born in August 1990 with the feral lambs around one month younger. The lambs were transported to Flock House and shorn and grazed together from the 21 January 1991 until 1 June 1991. There was no difference in the geometric mean of faecal egg counts between the different breeds (p=0.11). Lambs were fly struck from February to May with 33%, 10%, 10% of Merinos, Romneys and Wiltshires being attached. No feral lambs were fly struck. Most flystrike was caused by the Australian green blowfly (Lucila cuprina). The Wiltshire breed had the lowest dag score while the feral sheep had a dag score consistently lower than the Romney and Merino breeds (p<0.001). The wet weight of dag clipped at the end of the experiment was 4

Angora goat production from different legumes mixed with ryegrass - Stevens DR; Casey MJ; Lucas RJ; Baxter GS; Miller KB (Proceedings of the New Zealand Society of Animal Production, 1992)
Analyses of live weights at birth, weaning (4 months of age) and at the yearling stage from 360 fallow deer born in 19887 to 1990 were carried out to examine non-genetic effects and to provide preliminary estimates of heritability and genetic correlations. Weights of breeding does were also analysed. Fifteen sires (17 mating groups) were involved, with 2 sires repeated across years. After adjustment for fixed effects, coefficients of phenotypic variation were 10.5, 8.2 and 5.7% respectively for the three weights. The range of birth dates within year, excluding 3 outliers, averaged 36 days (s.d. 7.9 days). The differences in weight between males and females were 0.27, 2.5 and 9.3 kg at birth, weaning and the yearling stage. Regressions of live weights on birth date were zero, -0.15

The behaviour and welfare of calves during unloading after transportation - Bremner KJ; Matthews LR; Brears DJ; Painting AM (Proceedings of the New Zealand Society of Animal Production, 1992)
Computers traditionally make their first appearance in a business as a tool to automate time consuming tasks such as accounting, inventory control and document preparation. However, the true value of a computer system often lies in its ability to provide timely summaries and analyses of business performance. Business information requirements can be broadly categorised into three areas: operational processing (day to day tasks, data capture), management information (reporting and tracking, tactical planning) and decision support (strategic planning). Depending on the software used, a computer system can provide information from any of these areas. However, it is unlikely that any single software package can meet all the information needs of a business. It is becoming increasingly important for data to be easily transferred between systems. This paper looks at the various types of software available, what kinds of information each can provide and the need for integration between packages to provide the "total picture".

A bibliographic database on the biology of the sheep and goat - Brief Communication - Davies AS (Proceedings of the New Zealand Society of Animal Production, 1992)
Interest in gathering physical data on individual farms has escalated in recent years with the establishment of a number of focal farm schemes throughout the country. These schemes are aimed at identifying constraints to farm production at a local level, and then demonstrating techniques to overcome these constraints and hence increase production accordingly. This paper reviews the Northland Focal Farm Scheme and shows that this process of technology uptake by farmers outside such a monitoring scheme is slow to occur. Farmer confidence and other personal factors appear to be major limitations to management change and increased production on many farms.

Blood metabolites near calving in twin-pregnant and single- pregnant cows - Morris CA; Day AM; Jones KR (Proceedings of the New Zealand Society of Animal Production, 1992)
This trial was designed to test the hypothesis that increased faecal egg counts (FEC) of fleeceweight-selected (FW) lambs over control (C) lambs represented a decreased resistance to internal parasitism in FW lambs. Measurements were recorded over a 42 day period from late February 1991 using August-born lambs from the Massey University FW and C flocks. All lambs were drenched with ivermectin on day 0. Lambs of each sex and flock were randomly allocated within sire (4 per flock) to receive an albendazole controlled release capsule (+ALB). Ewes and rams were run separately. Midside wool growth, liveweight, and FEC were recorded, and estimates of dry matter intake were inferred from chromate analyses. The FW lambs had consistently higher FEC's than C lambs. Significant differences were observed by flock and ALB treatment in both wool production and liveweight gain, but no significant flock-by-ALB interaction were detected. Trends in production traits indicated that the superiority of FW lambs may have increased in situations where the development of adult worm burdens was continually suppressed. However, no clear evidence was found to show that FEC is a reliable indicator of a sheep's resistance to production losses arising out of internal parasitism.

Breed variation in expression of faecal nematode egg count - A Brief Communication - Watson TG; Hosking BC; Hurford AP (Proceedings of the New Zealand Society of Animal Production, 1992)
Five two-tooth Coopworth ewes were used to monitor the effects of changing caecal pH on magnesium (Mg) solubility and absorption pH change was induced by infusion of volatile fatty acid (VFA) (0, 220, 440, 660, 880 mmol; ration 0.80:0.15:0.05 acetic:propionic:butyric in 2016 ml of deionised water) into the terminal ileum for 24 h. Treatments were randomly applied to each animal using a latin square design. During the infusion samples of blood and urine were taken at 4 h intervals and proximal colonic digesta at 4, 16 and 24 h. Apparent Mg absorption from the large intestine was estimated from changes in plasma Mg concentration and urinary Mg excretion. Sixteen hours after the commencement of infusion digesta pH decreased and Mg solubility increased. For example, with the 880 mmol infusion digesta pH had decreased by 2.1

The breeding season of pubertal red deer hinds - Duckworth JA; Barrell GK (Proceedings of the New Zealand Society of Animal Production, 1992)
This paper summarises a series of experiments near Rotorua in which the liveweight changes of sheep grazed on pasture under Pinus Radiata was measured. In general terms sheep performance was lower as the tree stocking increased. Long term experiments have shown that under continuous grazing, sheep performance declines with increased tree stocking from as early as tree age 5 years. Feed allowance experiments indicated there may be a general decline in the feed value of pasture growing under Pinus Radiata. The effects were minor at tree stockings up to 100 stems per hectare. The effects would be minimised by offering higher allowances, to provide greater feed selection for the stock.

Cell proliferation during fibre growth initiation in ferret hair follicles - Saywell DP; Nixon AJ (Proceedings of the New Zealand Society of Animal Production, 1992)
intake and liveweight change of 7-month hoggets was measured when ad lib grazing steep hill pastures containing 10, 40 and 50% dead matter above 2 cm, in autumn. Two groups of 24 sheep from a "biological" and a "conventional" farming system were used in the trial. Digestible organic matter intake/kg liveweight and liveweight change were affected by dead matter content (P<0.05) but were similar for biological and conventional hoggets (P>0.1) despite high faecal egg counts in biological sheep. Better performance on high quality pasture was attributed to a higher organic matter digestibility and lower dead matter content in the diet, possibly due to the greater accessibility of green matter in the grazed horizons.

Comparative performance of ewes shorn either once-yearly or 3 times in 2 years - Sumner RMW; Webby RW; Winter RD (Proceedings of the New Zealand Society of Animal Production, 1992)
The determinants of wool production per unit area of skin are reviewed, and found to be dominated by follicle volume. Evidence is presented to show that follicle cells destined to become fibre cells differentiate into a continuum of cell types rather than discrete populations of medullary, ortho- and paracortical cells as the literature suggests. Fibres of the same dimensions grown by a sheep at one point in time contain differing proportions of these cell types. It is hypothesised that there is a degree of independence between fibre volume and cell differentiation. Medulla formation is explained in terms of competition between follicles for keratin precursors, so that fibre volume exceeds the available volume of keratin. A similar mechanism is proposed for the cortex, where paracortex and mesocortex become less prevalent as total fibre volume increases. It is concluded that a model for fibre formation can be considered in two parts: one which generates fibre volume and another which determines cell type within that volume.

A comparison between subjective and objective (carcass weight plus GR or the Hennessy Grading Probe) methods for classifying lamb carcasses - Kirton AH; Mercer GJK; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1992)
Stress research in farm animals is becoming increasingly important as a result of public concern for the welfare of animals and the ongoing need to increase the efficiency of animal production. Changes in the behaviour of animals is often the first indicator that a particular farming practice may be aversive or stressful. For example, cattle housed indoors on concrete floors have fewer resting bouts than those on deep litter or at pasture. Subsequent measurement of a variety of physiological parameters confirmed that lying down on slatted floors is stressful. Changes were noted in the episodic secretory pattern of glucocorticosterioid hormone, in the cortisol response to challenge with a standard dose of ACTH (1-24) and in heart rate. Ongoing studies with dairy cattle indicate that the frequencies and types of fly-avoidance behaviours utilised by animals without tails differ from those with tails. In addition, animals without tails have a higher number of flies on the body. Physiological parameters will be monitored to determine if the decreased ability of cattle without tails to remove flies results in altered physiological responses indicative of stress. These studies show that a multi-disciplinary approach is required to quantify the relative stressfulness of various farming practices.

A comparison of grain and pasture finishing of heavyweight cattle - Muir PD; Cruickshank GJ; Smith NB; MacLean KS; Wallace GJ (Proceedings of the New Zealand Society of Animal Production, 1992)
Data for the years 1986 to 1990 from the "Kamo" out-of-season lambing flock were subjected to analyses to determine the genetic variation for lambing date. The response variate was date of lambing (provided the ewe had a chance to mate for an autumn lambing) and this was transformed to an underlying normal scale by treating it as an ordered categorical response. Restricted maximum likelihood (REML) analyses were performed using an animal model. Year of record and age of ewe were included as fixed effects. There were 870 ewes having a total of 1967 lambing records. The estimate of heritability for standardised lambing data was 0.23 and repeatability 0.36 while the heritability for litter size was 0.03. Preliminary multivariate analysis indicated that the genetic correlation between standardised lambing date and litter size to be 0.09. At the time of disbanding of the flock samples of ewes selected on the phenotypic response (i.e. number of times lambed in autumn) of the ewe or of her dam, were brought to Ruakura. In 1991 following a best linear unbiased prediction (BLUP) analyses these were assigned to Autumn and Spring lambing flocks on the basis of their breeding value (BV) for standardised date of lambing. The average BV for the Autumn flock was - 0.13 while that for spring was +0.07 and there was a 26 day difference in mean lambing date (167 vs 193).

Comparison of growth, hogget fleece weight and reproductive traits of three sheep breeds from a flock selected for prolificacy and a Romney control flock - McEwan JC; Davis GH; Dodds KG; Fennessy PF; Clarke JN; Bruce GD; Hishon MG (Proceedings of the New Zealand Society of Animal Production, 1992)
The total glucose concentration of a medium changes with the extent of serum supplementation, and this may have an effect on embryonic development in vitro. In this study, 1- and 2-cell sheep embryos (N+109) were cultured for approximately 120 hours at 39 C under humidified 5% CO2, 5%)2 and 90% N2 in Synthetic Oviduct Fluid medium (SOF) supplemented with 20% human serum and a total glucose concentration of either 1.5 mM (modified-SOF) or 2.3 mM (unmodified-SOF). A slight effect was observed on the proportion of embryos developing to at least the expanded blastocyst stage (63% and 48% for modified-SOF and unmodified-SOF, respectively, P<0.1). Twenty-eight blastocysts from each treatment were selected and transferred to 28 synchronised, mature ewes (2 blastocysts per ewe). Pregnancy and number of foetuses were determined by ultrasonography 54 days after transfer. All ewes were pregnant and survival of embryos was 82% and 71% for modified-SOF and SOF, respectively. However, a high post-natal mortality rate was observed (37%), which was mostly attributed to a relatively high birthweight of dead lambs (6.4

A comparison of internal parasitism in fleeceweight-selected and control Romney sheep - Howse SW; Blair HT; Garrick DJ; Pomroy WE (Proceedings of the New Zealand Society of Animal Production, 1992)
Rising three year old Angus steers were fed on either ryegrass/subterranean clover pasture or a high grain ration (70% maize grain/ 30% pasture silage) for an adjustment period of 2 weeks and an experimental period of 12 weeks. Then cattle were slaughtered initially and 10 cattle from each treatment group were slaughtered after 6, 10 and 14 weeks. Cattle offered the high grain ration had feed intakes of up to 2.7% of bodyweight and over the 12 weeks experimental period average liveweight gains of 1.4 and 2.0 kg/d were achieved in the pasture and grain fed groups, respectively. Carcass weight increased from 316 kg to 363 kg in the pasture group and 406 kg in the grain fed group at final slaughter. Intramuscular (chemical) fat at the 12th rib increased from 13% to 23% and was not affected by diet. Levels of intramuscular fat were up to 38% and were similar to those reported for Japanese Wagyu beef. Lean meat colour was significantly brighter (P<0.001) as a result of grain feeding and the incidence of yellow fat was reduced.

Computer Applications: Meeting the information needs of a business - Abell W (Proceedings of the New Zealand Society of Animal Production, 1992)
Direct selection for 13-month live weight in NZ Angus cattle for 15 years has resulted in 17% heavier yearlings and 12% heavier adults when compared with unselected control animals. The mean daily food intake of growth-selected bulls is higher on a per head basis but is similar when adjusted for differences in live weight. The objective of this paper is to model the efficiency of a breeding cow herd, including replacements, derived from selected and control lines. The index of efficiency used is weight of calf weaned per unit weight of winter feed required. Published performance data from the 2 herds are used to quantify calf output and feed requirements are based on published growth patterns in the 2 herds. Our analyses show that, for the same winter feed requirement, the selected herd when compared with the control herd would have: 88 vs 100 cows wintered; 65 vs 72 calves weaned, and mean calf weaning weight would be 174 vs 158 kg per head. Efficiency was estimated to be 99.8 vs 100 units. Theses results indicate that while selection for yearling weight has resulted in heavier calves and breeding cows, the calculated extra winter feed costs associated with the heavier selected herd makes them no more efficient than the randomly bred control herd. For the selected herd to be more efficient, either a reproductive advantage well in excess of the 3 percent point advantage achieved would be required, or the metabolic efficiency of the selected cows would need to increase. In economic terms, the selected herd may be more efficient than the control herd for 2 reasons. Firstly, since herd size is lower, total herd costs are likely to be lower. Secondly, if a premium exists for heavier calves, the calves from the selected herd are likely to be worth more per head.

Computer use on my farm - Harris PR (Proceedings of the New Zealand Society of Animal Production, 1992)
The objective of the experiments was to test the hypothesis that pretreatment with progesterone would increase the proportion of animals exhibiting behavioural oestrus following injection of oestradiol-17

Concentrations of oestrone sulphate in milk during pregnancy in dairy cows - Henderson KM; Karanikolas M; Kenealy L; Macmillan KL (Proceedings of the New Zealand Society of Animal Production, 1992)
Host resistance to internal parasites, as measured by faecal egg count and dagginess was investigated in ram lambs born in the 1981-83 years (approximately generation 3) from the Woodlands selection lines. Lines were selected for either: number of lambs born, 100 day weight, hogget fleece weight and a production index in which all three traits are combined; a fifth line was a randomly selected control. Ram lambs were drenched with anthelmintic and then exposed to contaminated pasture for a period of 6-7 weeks and then faecal sampled. Total plasma protein, albumin and pepsinogen were measured. The results demonstrated significant variation between selection lines in faecal egg count, dag score, liveweight gain, wool growth and blood plasma parameters. Between selection lines, faecal egg count was positively correlated with liveweight gain (0.95) and wool growth (0.41). Blood pepsinogen and total blood protein were both negatively associated with faecal egg count and liveweight gain (correlations of -0.51 to -0.90). Using sire variation within selection line (progeny of 65 sires) produced heritability estimates of 0.13

A conceptual framework for an expert system to improve drying off decisions on seasonal supply dairy farms - Brief Communication - Gray DI; Lynch GA; Lockhart JC; Parker WJ; Todd EG; Brookes IM (Proceedings of the New Zealand Society of Animal Production, 1992)
Forty Border Leicester (BL) and forty-eight Dorset Down (DD) ewe hoggets (7.5mo) that had been farmed together were scanned using a real-time ultrasound machine, at six sites with one muscle depth (B) and five subcutaneous fat depth measurements (R - tissue depth over fifth rib, C - backfat over last rib, GR, L - backfat over last lumbar vertebrae, T - fat over tail) being taken. Comparisons of tissue ratios (individual fat depth divided by B) were used to characterise subcutaneous fat distribution. From these ratios it was found that the DD had 9%, 10% and 6% greater ratios at R, L and T respectively, and 7% lower ratios at C and GR. Breed differences at R, GR and T were significant (P<0.05). It was concluded that true genetic differences in subcutaneous fat distribution existed between the genotypes studied. These findings have implications for carcass classification, for breeding programmes for lean growth, and for comparisons of the fatness of different genotypes.

Dairy Production in developing countries - McDowell RE (Proceedings of the New Zealand Society of Animal Production, 1992)
Measurement accuracy for ultrasonic tissue depths was examined in order to determine the relative importance of factors affecting it. Repeatabilities for ultrasonic fat depth (UFD) and ultrasonic muscle depth (UMD) were assessed from repeated runs (2) in three groups of animals; Dorset Down ewes (LW=45.4kg, 7.5mo, n=50), Coopworth rams (LW=51.5kg, 11mo, n-50) and Dorset Down rams (LW=38kg, 4.5mo, n=50). Repeatability values were higher for UMD (0.77, 0.95 & 0.87 for the 3 groups, respectively) than for UFD (0.63, 0.84 & 0.82, respectively). Lower repeatabilities were due to high within-animal variance rather than low between-animal variance. Measurements made on videotaped images demonstrated that image registration had a great effect on repeatability, with image interpretation having a negligible effect. A comparison of two operators differing in experience showed that fat depth was measured equally accurately by both operators but that the experienced operator measured muscle depth more accurately. It was concluded that tissue depths can be accurately assessed from one measurement.

Developments in breeding Perendale sheep for resistance or susceptibility to internal nematode parasites - Watson TG; Hosking BC; Hurford AP; Mather BC (Proceedings of the New Zealand Society of Animal Production, 1992)
The liveweight gain, carrying capacity and total animal production from different pastures grazed by year old angora type wether goats were assessed during the spring, summer and autumn of two years. 'Grasslands Nui' perennial ryegrass (Lolium perenne L.) was sown with 'Grasslands Tahora' white clover (Trifolium repens L.), 'Grasslands Pawera' red clover (Trifolium pratense L.), or 'Grasslands Maku' lotus (Lotus pendunculatus Cav.) in December 1988 and measurements began in September 1989. Goat liveweight gain in spring was similar on all treatments averaging 130g/hd/day. Summer liveweight gain on red clover was 76g/hd/day, greater than the average of 56g/hd/day for white clover and lotus pastures. Autumn liveweight gains were not significantly different averaging 44g/hd/day. Carrying capacity was lowest on lotus pastures in all seasons. White clover pastures had the highest carrying capacity in all seasons though only significantly greater than red clover in autumn. No differences in total animal production per hectare were found in spring. Red clover, however, had 45% more animal production in summer than white clover or lotus pastures. This increased production was attributed to a greater consumption of legume due to both the dominance of red clover in the upper sward horizons and an active selection of red clover by the goats.

Dose-response to a single injection of PMSG in Merino ewes carrying a double copy of the Booroola FecB gene - Shackell GH; Isaacs KL (Proceedings of the New Zealand Society of Animal Production, 1992)
Sheep shorn with a cover-comb were compared with conventionally shorn sheep in two experiments. In the first experiment, ewe and lamb performance and some aspects of ewe physiology were measured with 60 Romney ewes which were shorn before lambing. In the second experiment, oxygen consumption by 12 Romney hoggets was measured before and after shearing in calorimeters at 10 C. In the first experiment, herbage intake by ewes in the 3 weeks post- shearing was not affected by shearing method. There were no treatment effects on the liveweight of ewes, birthweight and growth rate of lambs nor on ewe wool production during the 2 months post-shearing. However, on days 1 and 3 after shearing the plasma concentrations of non- esterified fatty acids and of 3- hydroxybutyrate were higher in the ewes shorn with the conventional comb than in those shorn with the cover comb. In the second experiment oxygen consumption was increased immediately after shearing, by 47% and 25% in the conventional- and cover-comb sheep respectively. The difference between the two groups, which remained significant until day 12 post-shearing, decreased with time until it disappeared on day 22. The results show that sheep shorn with the cover-comb were significantly more resistant to cold conditions than those shorn with the conventional comb, particularly during the 3 days post-shearing. Use of the cover comb may offer a useful low cost method of reducing the effects of cold conditions after shearing, but its effects on mortality have not been demonstrated.

The effect of condensed tannin containing diets on whole body amino acid utilisation in Romney sheep: consequences for wool growth - Lee J; Harris PM; Sinclair BR; Treloar BP (Proceedings of the New Zealand Society of Animal Production, 1992)
Fleece production, fibre characteristics and spring liveweight in adult alpaca, tui and cria farmed in the South Island are reported. The shearing and fibre classing techniques are also described. Liveweight at shearing was 63.9kg, 65.7kg and 67.8kg for 1989, 1990 and 1991 respectively which is markedly increased from the South American records. The latter two years are significantly (p<0.05) higher than the initial year (1989) following importation. Clean fleece weight was similar in the latter two years, averaging 1.8 kg, but fibre diameter was significantly (p<0.05) coarser from 25.2

Effect of glucose level in culture medium on survival of in vitro cultured sheep embryos following transfer to recipient ewes - Thompson JG; Simpson AC; Pugh PA; McGowan LT; James RW; Berg DK; Payne SR; Tervit HR (Proceedings of the New Zealand Society of Animal Production, 1992)
The commencement and course of cell proliferation is described in proanagen hair follicles of ferrets. Initiation of autumn fur growth was synchronised in 32 animals using melatonin implants. Skin samples containing S-phase cells labelled in vivo with bromodeoxyuridine were collected from groups of four animals up until the time of development of metanagen follicles at 14 days post-implant. Cells were visualised by an indirect immunocytochemical method and counts made of proliferating cells in the hair germ, epithelial strand/outer root sheath, connective tissue sheath and dermal papilla. Telogen follicles showed no labelling in all four tissues until 4 days after melatonin implant. The largest number of proliferating cells were in the hair germ, which formed the new fibre and inner root sheath. The cell labelling index for this tissue remained high at 14 days post-implant. In other tissues, cell proliferation reached peaks during mid to late proanagen, then declined as the metanagen state was reached. These results indicate that some key signalling events controlling ferret hair growth occur between 0 and 4 days after the melatonin implant, and illustrate the separate processes of follicular regeneration and fibre growth occurring in proanagen follicles.

Effect of oestrogen pre-treatment and duration of CIDR treatment on pattern of onset of oestrus in ewes - Smith JF; Parr J (Proceedings of the New Zealand Society of Animal Production, 1992)
When they were weaned at five and a half months of age, 33 Angus heifers were randomly divided into two groups representing different planes of nutrition. From weaning until two months before calving which began on 15 July 1977 the liveweight difference between the two groups was steadily increased until the high plane group (HP) weighed 17 kg more than the low plane group (LP) on 17 May 1977. From then until calving the high plane group was fed to maintain constant liveweight, while the low plane group was fed to gain liveweight at the rate of 0.3 kg/day. When calving began both groups weighed the same average liveweight (415 kg). Calf birth weight was affected by nutritional treatment (HP 26.2

Effect of physical parameters on ram spermatozoal motility - Upreti GC; Oliver J; Munday R; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1992)
Local sympathectomy was achieved by injecting 6-hydroxydopamine into the dermis at two sites on the right midside of each of three Merino wethers. Saline was injected into matching sites on the left midside. After one week, noradrenaline was injected into one site on each side and saline into the other. Colchicine was administered into all sites immediately after noradrenaline, skin biopsies removed from each site two hours later and histological preparations assessed for the accumulation of mitoses in wool follicles. Compared with saline treated sites, noradrenaline significantly depressed the number of accumulated mitoses at control and sympathectomised sites by 34 and 36% respectively (P=0.002). A pharmacological dose of noradrenaline therefore has the potential to reduce wool production. Sympathectomy increased mitotic rate at saline and noradrenaline treated sites by 16 and 18% respectively, although this increase was not significant at the 5% level (P=0.0094). Elevation of mitotic activity via elimination of endogenous sources of noradrenaline may help to explain the mechanism by which surgical sympathectomy has previously been reported to increase wool production.

The effect of pretreatment with progesterone on the oestrous response to oestradiol-17Beta benzoate in the post-partum dairy cow - McDougall S; Burke CR; Macmillan KL; Williamson NB (Proceedings of the New Zealand Society of Animal Production, 1992)
Crossbreeding with Booroola Merino rams was initiated in 1986 in Israel to transfer the FecB allele to the Awassi (Aw) and the Assaf (As) dairy breeds to increase their prolificacy. The prolificacy of the F1 ewes was higher by about 0.6 lambs/ewe lambing (P<0.05) over the prolificacy of Aw and As ewes. Growth rate up to 150 days of age did not differ between As,

Effect of selection for productive traits on internal parasite resistance in sheep - McEwan JC; Mason P; Baker RL; Clarke JN; Hickey SM; Turner K (Proceedings of the New Zealand Society of Animal Production, 1992)
The distribution of condensed tannins (CT) in plants, their mode of action and benefits to ruminant nutrition are briefly reviewed. Data are presented showing the CT in lotus species reduced rumen degradation of protein and increased its flow to the intestine, but an increased amino acid absorption only occurred with Lotus corniculatus, suggesting the CT in Lotus pedunculatus prevented enzymic hydrolysis of the protected protein. The extent to which CT in Lotus pendunculatus depressed nitrogen (N) digestion was similar when fed as a sole diet and when fed as a third of the diet with pasture. The implications of these results are that both concentration and type of CT are important in affecting nutritive value, and that these factors need to be resolved before an effective plant selection program can be undertaken.

Effect of sire, breed and age on plasma FSH concentrations in FecB FecB and Fec+ Fec+ Booroola rams before and after castration - Isaacs KL; McNatty KP; McLeod BJ; Condell L; Littlejohn RP (Proceedings of the New Zealand Society of Animal Production, 1992)
Feed intake and wool production data on unmated, single- and twin-bearing/rearing ewes from a year-long field trial were incorporated into feed budget models of a hill country farm. Increasing the basal liveweight of an unmated ewe from an average of 45 to 55 kg increased greasy wool production from 4.15 to 5.10 kg/ewe. Relative to the annual feed requirements (614 kg DM/y) of a typical breeding ewe (1 sheep stock unit (ssu) on the case farm the annual feed requirements of unmated 45, 50 and 55 kg ewes were estimated to be 0.58, 0.66 and 0.72 ssu. At 1991 costs and prices the gross margins (GM) were $15.50/ssu for breeding ewes (100% lambs weaned) and, depending on liveweight, from $7.12 to $8.11/ssu for the all-wool options. The breeding ewe policy remained more profitable even if low lamb prices or a poor lambing percentage were achieved.

The effect of sward surface height on ingestive behaviour and intake of once-bred and non-pregnant heifers under continuous stocking management in early winter - Inwood PR; Morris ST; Parker WJ; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1992)
Damage to soils and pastures in early Spring is a significant factor reducing pasture growth, feed utilisation and animal production on NZ dairy farms. Farmers have sought and may have found a management solution to this problem. It involves the early removal of dairy cows from pasture, after a period of grazing that is sufficient to meet the dry-matter intake needs of the cows. For example the colostrum herd might graze on pasture only at night, and spend the period between morning and afternoon milkings on the cowshed yard. The main herd will be on pasture during the daytime, but may be taken off pasture at 9.00 after 3 to 4 hours grazing, and stood on the cowshed yard until morning milking. This limits the extent of treading and reduced damage to soils and pasture, allowing the farm to sustain higher pasture growth rates, maintain a higher average pasture cover and achieve a longer first rotation. Dairy farmers have found they can stand lactating dairy cows without special facilities and without the need for supplementary feed provided certain conditions are met. The best place to stand cows from farmers experience is on the cowsheds concrete yard. Cows are used to standing there and the concrete is cleaned daily of stones, so risk of stone bruising to hooves is minimal. While space on the yard is limited, few cows lie down on the concrete. The close contact means they keep each other warm, and they may be less exposed to weather than in the paddock. There appears to be no detrimental effect on daily per cow production from this treatment and production data will present to illustrate this.

Effects of GnRH and of single versus multiple mating on the conception rate in alpacas - Knight TW; Death A; Wyeth T; Hill F (Proceedings of the New Zealand Society of Animal Production, 1992)
Herd owners comment that they are having increasing difficulty getting their higher producing, higher Breeding Index (BI) cows to conceive. The reports published on local and overseas data are inconclusive and do not substantiate their concern. A solution to this dilemma would be analyses of contemporary groups within herds with production records stored in the national data base. This would allow for the effects of different feeding practices. Any factor which increased the likelihood of a cow failing to conceive to a first insemination will reduce income by $110/return. If the delay in conception must be rectified by induction, the cost of $320 and increased to $700 if the cow fails to conceive. These changes in income mean that if a herd of 170 cows has its pregnancy rate per breeding reduced from 60% to 59%, the estimated loss would total $955. This emphasises the cost of delays in conception date.

Effects of grazing pressure and competition on growth rate of Merino and Romney lambs - Muir PD; Cruickshank GJ; Wallace GJ; MacLean KS; Smith NB (Proceedings of the New Zealand Society of Animal Production, 1992)
The effect of nutritional management of Angora goats on fibre production and fibre quality was investigated over two years. After shearing in August, does were fed either maintenance (MPA) or ad libitum (HPA ryegrass/white clover pasture (approximately 1.0 kg and >4kg DM/head/day respectively). In October half the does were removed from each allowance group and introduced into the alternate allowance group. This was repeated in early February, allowance groups being balanced for their previous allowance history. Fleece weights were recorded at shearing in February and August. Fibre diameter, medullation and kemp levels were measured at shearing in February and August and also in October and May. Doe live weights were recorded monthly and when fleece measurements were made. After one year of measurements, does were completely randomised onto new pasture allowances and the experiment was repeated. Nutritional treatments generated liveweight differences between HPA and MPA does throughout the year (P<0.05). February fleece weights were similar in both HPA and MPA groups in 1990 (1.73 vs 1.67; s.e.d 0.067 kg for HPA vs MPA respectively) and in 1991 (1.43 vs 1.41; s.e.d 0.060 kg for HPA vs MPA respectively) though approximately 25% lower than in 1990. August fleece weights were similar in 1990 and 1991 but were approximately 20% higher in HPA does than in MPA does (1.46 vs 1.26; s.e.d 0.051 kg for HPA vs MPA respectively in 1990 and 1.49 vs 1.20; s.e.d 0.040 kg for HPA vs MPA respectively in 1991). Increased August fleece weight was associated with increased fibre diameter (34.9 vs 32.7; s.e.d 0.52

Effects of location and source of ewes and rams on the onset of oestrus in Romney ewes - Knight TW; Muir PD; O'Neill KT; Wallace GJ; Hamilton GJ; McLean K (Proceedings of the New Zealand Society of Animal Production, 1992)
Spermatozoal motility is known to be influenced both by the diluent used and by the physical parameters involved in the processing of semen. We have evaluated the effect of cooling and dilution on ram spermatozoal motility in a defined semen diluent. The results indicated that ram semen is best stored at 15 C, this temperature being reached by cooling at a rate not greater than 3 C per minute. Time (up to 60 minutes from semen collection) and extent of dilution (500 or 800 x 10 6 spermatozoa per mil) were found to have no effect upon maintenance of spermatozoal motility.

The effects of milking once daily throughout lactation on the performance of dairy cows grazing on pasture - Holmes CW; Wilson GF; MacKenzie DDS; Purchas J (Proceedings of the New Zealand Society of Animal Production, 1992)
The influence of selection for rapid (Fast GC) or slow (Slow GC) clearance of exogenous glucose on the pH of lamb meat was investigated using preslaughter stress, adrenaline and energy supplement treatments. Ultimate pH values were elevated (P<0.001) by a high level of preslaughter stress in the Fast GC line only. This response was suppressed by an oral energy supplement, indicating that recharge of muscle glycogen stores was impaired. The demonstration of this genetic relationship makes the selection lines valuable for study of the influence on meat quality of post mortem energy metabolism in muscles.

Effects of month and PMSG on the interval from CIDR removal to ovulation in Romney and Merino ewes - Knight TW; O'Neill K; Ridland M; Hamilton G; Death A; Wyeth T (Proceedings of the New Zealand Society of Animal Production, 1992)
Ingestive behaviour and herbage intake were measured in 36 twenty-month old pregnant and non-pregnant Hereford x Friesian heifers with an initial liveweight of 360

Effects of shearing method on the physiology and productivity of sheep - Holmes CW; Kamil KA; Parker WJ; MacKenzie DDS; Purchas G; Kidd R (Proceedings of the New Zealand Society of Animal Production, 1992)
Three groups of sheep housed in metabolism crates were fed Lotus corniculatus (low tannin), L. pendunculatus (medium tannin) and ryegrass pasture (control) respectively. After a period of adaptation to each of the diets, labelled 35S-cysteine and

Effects of suppressed prolactin levels on wool growth in Romney ewes - McCloghry CE; Foldes A; Rintoul AJ; Hollis DE; Baker PJ; Maxwell CA; Kennedy JP; Wynn PC (Proceedings of the New Zealand Society of Animal Production, 1992)
Performance data were collected between October 1985 and October 1991 from a flock of approximately 600 mixed-age Romney ewes allocated to 3 equal sized age-balanced groups and grazed on the same area at Whatawhata Research Centre. Two groups were shorn 3 times in 2 years at approximately 8-monthly intervals. One group was shorn in May, January and October and the other shorn in January, October and May during each succeeding 2 year period. The third group were shorn once-yearly in October. Eight-monthly shorn ewes weaned heavier lambs and grew more greasy and clean wool than once-yearly shorn ewes. Shearing treatment did not affect ewe live weight after shearing in October or any parameter of lamb production, other than lamb weaning weight. Incidence of casting was less than 1%. Net wool returns from 8-monthly shorn ewes exceeded that of once-yearly ewes with the associated benefit that shearing 8-monthly as a split flock system would improve cashflow relative to a once yearly system.

Expected responses in carcass composition to selection for muscularity in sheep - Waldron DF; Clarke JN; Rae AL; Woods EG (Proceedings of the New Zealand Society of Animal Production, 1992)
Fifty nine mixed age ewes from high (H) and low (L) faecal egg count (FEC) selection lines were used in a MOET programme. Three years of reproductive data were also recorded in 714 ewes from the 2 selection lines and their control line (C). The mean (

Factors affecting repeatability of tissue depth determination by real-time ultrasound in sheep - Young MJ; Deaker JM; Logan CM (Proceedings of the New Zealand Society of Animal Production, 1992)
The behaviour of 7476 calves transported on double- or triple- decker trucks was studied during unloading. Recorded behaviour was classified into 2 categories (upright or not upright) and the frequencies of these at three ramp slopes (4.2, 12 and 18.8 ) are presented. The proportions of animals upright on the 3 slopes (low, medium and high) were 93, 74 and 20%. On average, 100 calves were unloaded in 5.3, 7.7 and 7.1 min down the low, medium and high slopes, respectively. Improvements in welfare of bobby calves and probably reduced bruising would result if ramp slopes were kept at less than about 12 so that most animals could remain upright.

Fibre production, shearing procedure and fleece characteristics of alpacas farmed in New Zealand - Wuliji T; Davis GH; Andrews RN; Turner P; Moore GH; Dodds KG (Proceedings of the New Zealand Society of Animal Production, 1992)
Five treatment groups of 40 fine Merino wethers were offered grazing regimes over 2 treatment periods, to achieve a range of liveweight profiles. The first was from 16 October 1990 to 21 December 1990 while the second continued until 29 August 1991. Treatment period 1 generated significant differences in liveweight (P<0.001) between all groups and thereafter the sheep were grazed in 2 larger mobs consisting of groups 1-3 and 4 and 5. By the end of the first period liveweights were 48

Genetic parameters and performance of flocks selected for advanced lambing date - Smith JF; Johnson DL; Reid TC (Proceedings of the New Zealand Society of Animal Production, 1992)
Timing of the LH peak and ovulations in superovulated Coopworth ewes synchronised with progesterone-containing CIDR

Genetic parameters for live weights in fallow deer (Dama dama L.) - Morris CA; McCall JE; Baker RL; Southey BR (Proceedings of the New Zealand Society of Animal Production, 1992)
It is debatable whether or not genotype influences follicle- stimulating hormone (FSH) secretion in the Booroola ram. Where differences in FSH have been reported, these may have been due to effects of sire, breed and age rather than Booroola genotype. The aim of this study was to determine if these factors do influence FecB gene expression in plasma FSH concentrations in the Booroola ram. A total of 45 Booroola rams of known genotype, breed, age and sire were blood sampled (10 ml by jugular venepuncture) once daily for 11 days, castrated, bled once daily for further 13 days, and then three times weekly for a further 7 weeks. There were no gene-specific differences in mean plasma FSH concentrations before or after castration, or in the rate of the post- castration rise in FSH, between FecBFecB (BB) and Fec+Fec+ (++) rams. This was consistent when data from rams of three ages (1, 2 or 3 years) and of either Booroola Merino or Booroola Romney breeds were combined, or when genotypes, were compared within breeds, or within ages. There was, however, a significant effect of sire on plasma FSH concentrations, which was evident before but not after castration. These results suggest that variation in FSH between sire groups may explain differences previously attributed to genotype.

Growth and venison production from red deer grazing either red clover or perennial ryegrass/white clover pasture - Semiadi G; Barry TN; Wilson PR; Hodgson J; Purchas RW (Proceedings of the New Zealand Society of Animal Production, 1992)
Computers will become an increasingly important tool in animal management, as well as in most other areas of agricultural endeavour. Computers are commonly used for recording and analysing both research and centrally located production data, but seldom for on-farm use. This discussion concentrates on the traits that can be recorded at the farm level, and how these records can be used. System specifications for successful on-farm use are also outlined.

The importance of physiological measurements in farm animal stress research - Ladewig J; Matthews LR (Proceedings of the New Zealand Society of Animal Production, 1992)
Planned feeding programmes for farm livestock often require the use of repetitive calculations that vary in complexity. This paper outlines some of the planning tasks which can be performed using computerised models. These include: (1) calculation of nutrient requirements for specific production targets and/or production achievable from specific nutrient intakes (ii) diet formulation using linear programming to provide optimum combinations of dietary ingredients at minimum cost (iii) allocation of pasture to grazing animals based on functions relating herbage allowance or residual dry matter to herbage intake and (iv) medium to long-term feed planning using models that range from simple feed budgets to dynamic whole farm simulations. The planning applications of computers can be complemented with monitoring and record keeping software that allow predicted outcomes to be compared with actual events. Desirable features of computer software include ease of use, flexibility, capacity to link with other programmes, and regular revision and updating.

Interspecies hybrids of deer - a ruminant resource for gene mapping and quantitative trait studies - Tate ML; Manly HC; Emerson BC; Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1992)
Seasonal variation in prolactin secretion has been associated with changes in the pelage of a number of mammals. The aim of this study was to ascertain whether the suppression of prolactin levels commencing in late summer, affects wool growth in sheep with a seasonal pattern of wool growth. Twenty Romney ewes (n=10/group) received either 50mg bromocryptine (Parlodel LA

Investigations of wool follicle morphology and cell proliferation in sheep with different levels of wool production - Holle SA; Harris PM; Davies AS (Proceedings of the New Zealand Society of Animal Production, 1992)
No abstract supplied

Lamb and milk production in Awassi, Assaf, Booroola-Awassi and Booroola-Assaf sheep in Israel - Gootwine E; Braw-Tal R; Bor A; Goot H; Shalhevet D; Zenou A (Proceedings of the New Zealand Society of Animal Production, 1992)
The growth rates of Merino and Romney lambs were compared at three stocking rates (200, 100 and 50 lambs/hectare) but at the same herbage allowance (2 kg DM/head/day). To achieve this, lambs at lower stocking rates were allocated different areas (0.21, 0.4 and 0.8 ha) and shifted at different frequencies (5.1, 9.8 and 24.5 days, respectively). At each stocking, rate groups of 10 lambs of each breed were grazed both separately and together. Each treatment was replicated. Grazing clocks were used to record grazing times in the mixed grazing groups at both the high and low stocking rates. Romney lambs grew significantly faster than Merinos (P<0.001) at all stocking rates. As stocking rate increased there was an overall decrease in LWG (P<0.001). However LWG of Merinos decreased at a significantly faster rate (P<0.005). The effects of stocking rate on breed differences in LWG were supported by grazing data. At 50 lambs/ha, Merinos and Romneys grazed for 10.5 and 11.1 hrs/d, respectively. At 200 lambs/ha, Merinos grazed for 7.2 hrs/d, compared with 11.0 hrs/d Romneys. The pattern of grazing also changed, with Merinos spending more daytime grazing as stocking rate increased from 50 to 200 lambs/ha (60% versus 82%) whereas Romney continued to spend 80% of total grazing time as daytime grazers.

Lambs selected for fast glucose clearance have high meat pH levels when stressed before slaughter - Bray AR; Francis SM; O'Connell D; Bickerstaffe R (Proceedings of the New Zealand Society of Animal Production, 1992)
Two groups of 10 intact Border Leicester ram lambs (10 weeks old; 22.7

Magnesium Solubility in the caecum in response to pH changes - Dalley DE; Isherwood P; Sykes AR; Robson AB (Proceedings of the New Zealand Society of Animal Production, 1992)
We examined the practicality of using a combination of protein polymorphism and DNA fingerprinting to match up hinds and calves in nine separate mating groups of red deer with between 8 and 21 progeny each. Variation in 10 polymorphic proteins excluded 0.61 to 0.89 of the possible dam-calf combinations in each sire group, leaving between 2 and 200 pedigree combinations per group to be solved by DNA fingerprinting. Of the 44 sire-dam-calf combinations tested by DNA fingerprinting, 22 were excluded, while four calves matched the parents at all bands. However, 16 pedigrees were equivocal, due to the fact that one or both parents were not in a lane directly adjacent to the calf on the fingerprinting gel. The low probability of exclusion of protein testing in some sire groups, combined with the practical limitation of having to run each possible pedigree combination side by side on DNA fingerprinting gels, mean that the present techniques do not provide a routine method for identifying the dam-calf pairings in red deer mating groups on farms.

Management effects on seasonal fibre quality in Angora goats - Bown MD; Clayton JB; Bigham ML (Proceedings of the New Zealand Society of Animal Production, 1992)
Lambs grazing ryegrass infected with endophyte (Acremonium lolii) may exhibit staggers or diarrhoea or both, with little correlation between these two conditions. Associated mycotoxins/toxins other than the staggers-inducing lolitrems are likely to be responsible for metabolic changes causing reduced intake, elevated temperature and diarrhoea. These mycotoxins are not necessarily confined to the base of the leaf sheath and stem as is the case for lolitrems. The distribution of mycotoxins to proximal portions of vegetative ryegrass and the effect of these plant components on grazing animals was investigated. Following experimental confirmation in 1991 of nil correlation between staggers and diarrhoea, groups of lambs were grazed in autumn 1992 on 100% endophyte-infected hybrid ryegrass cv. Grasslands Marsden (Lollium boucheanum Kunth.), using a leader-follower system. Upper and lower leaves, and pseudostem were progressively removed by four groups of lambs on three day breaks, replicated twice. Liveweight gain ranged from 164 g/day in lambs having first offer, to 28 g/day in those grazing the base of the plants (P<0.01). Rectal temperature averaged 40.2 C being slightly above normal in all treatments. Faecal moisture was high; ranging from 79-87% throughout the experiment with no significant differences due to treatment. Observed faecal soiling was greatest in lambs receiving high leaf component (P<0.05). Clinical staggers, barely detectable in lambs grazing leaf, became severe as the proportion of pseudostem in the diet increased (P<0.01). In contrast to the clear association between endophyte and staggers in lambs grazing the base of infected ryegrass, consistently high faecal moisture, and consequent faecal soiling occurred regardless of the part of the plant consumed, but tended to be greatest in lambs grazing leaf. Analysis of plant components suggested that peramines may be associated with this problem.

Measurement of foetal size by ultrasonography and progesterone concentrations in pregnant alpacas - Ridland M; Knight TW; Wyeth TK (Proceedings of the New Zealand Society of Animal Production, 1992)
A high fleece weight Romney breeding flock (HFW) and a contemporary random control flock (RC) has been established at MAF Technology Woodlands Research Station by the intensive screening of ewe and ram hoggets from commercial flocks. This paper summaries production traits including reproductive performances, liveweight and fleece weight of the ewe flocks over the 7 years. The ovulation rate and number of multiple births per ewe lambed were higher for HFW than RC ewes 1.84 vs 1.75 (SE0.02, p<0.01) and 0.62 vs 0.56 (0.02, p<0.05). Number of lambs born per ewe joined, number of lambs reared per ewe lambed, the number of lambs weaned per lamb born and number of lambs weaned per ewe joined in HFW were 1.49 (SE0.02), 1.37 (0.02), 0.84 (0.01) higher in HFW (65.4kg; SE2.4) than in RC (61.3 kg; 2.4). The greasy fleece weight averaged 4.55 kg (SE 0.21) for HFW and 3.87 kg (0.21) for RC. This represents an average advantage of 17.6% (P<0.001) to HFW over 7 production years. The results indicate that the single trait selection for fleece weight will be associated with increases in other important productive traits in long woolled sheep.

Melatonin for cashmere production in breeding does - O'Neill KT; Litherland AJ; Hamilton G (Proceedings of the New Zealand Society of Animal Production, 1992)
Differences in onset of oestrus in Romney ewes has been observed between locations at similar latitudes in the North Island. Two experiments compared source of ewes and rams, and time of transfer of ewes between locations on the onset of oestrus in Romney ewes. In Expt 1, groups of 30 ewes were interchanged between Wanganui and Takapau on 14 Nov, 5 Dec and 8 Jan. The next day these ewes plus 30 local ewes were joined with 3 Poll Dorset rams. There were no effects of ewe source but ewes at Takapau joined on 15 Nov, 6 Dec and 9 Jan had earlier onsets-of-oestrus than ewes at Wanganui (P<0.05 to P<0.01). Ewes joined on 15 Nov and 6 Dec at Wanganui had a later (P<0.01) onset of oestrus than ewes joined on 9 Jan. In Expt 2, 60 ewes and 3 Poll Dorset rams were interchanged between Wanganui and Poukawa on 13 Nov. These ewes plus 60 local ewes were randomly divided in half and recombined to form 2 mixed groups which were joined with 3 Poukawa or 3 Wanganui Poll Dorset rams. Onset of oestrus was earlier at Poukawa (P<0.001) and for ewes joined with Wanganui rams (P<0.001) but there were no effects of ewe source.

Melatonin secretion in Romney ewes differing in wool growth and reproduction is not aligned to photoperiod during spring and summer - Scott IC; Heath D; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1992)
A progeny test involving Romney (n=5) and Poll Dorset (n+5) rams mated to Romney ewes was conducted to examine the relationship between testis size and endocrine parameters, measured during the transitional period from the non-breeding to the breeding season, in rams, and reproductive performance of their daughters in the first and second breeding seasons. More of the Poll Dorset cross hoggets reached puberty during the first breeding season (80 v. 60%; P<0.01) associated with earlier onset (13 v. 22 May; P<0.10) at younger ages (264 v. 276 days; P<0.10) and more oestrous cycles (2.7 v. 2.0; P<0.05) than for Romney hoggets. The date of onset of the second breeding season was influenced by breed (P<0.001) and sire within breed (P<0.05). These differences between Romney and Poll Dorset cross animals in reproductive performance were associated with differences between their sires in the pattern of seasonal variation in testis size and plasma gonadotrophin concentrations. However, within-breed correlations between testicular and endocrine parameters in the sires and date of onset of the breeding season in the offspring were low. It is concluded that, while some of the testis and endocrine parameters could potentially be used as selection criteria for date of onset of the breeding season in ewes, further studies are needed before these parameters can be incorporated into selection programmes.

Modelling herd efficiency in liveweight-selected and control Angus cattle - McMillan WH; Morris CA; McCall DG (Proceedings of the New Zealand Society of Animal Production, 1992)
The growth and sexual development of red deer calves born early (12 male, 12 female), with an average birth date of 22 October 1990

A modelling study of the productivity and profitability of unmated and mated ewes on North Island hill country - Parker WJ; Gray DI; Morris ST; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1992)
Five groups (15-30) of Romney or Merino ewes were synchronised with CIDR devices for 12 days in March or April. In all but one group of Romney ewes 400IU PMSG was injected at CIDR removal. Intervals to onset of oestrus and ovulation were determined by recording crayon marks and laparoscopy respectively every 4 hours. Interval to ovulation was not affected by ewe breed or month of treatment, but it was 7.9 hours earlier in ewes injected with PMSG (48.9h vs 56.8h P<0.001) and the variance was less (13.4h vs 35.7h P<0.05). Interval to oestrus was affected by breed of ewe, date of synchronisation and use of PMSG.

The National Database for sheep genetic evaluation and research - Garrick DJ; Clarke JN; Callow CF (Proceedings of the New Zealand Society of Animal Production, 1992)
Lactating and non-lactating does were allocated on August 1989 down lengths to seven groups. Four of the groups received a single slow release melatonin implant (Regulin) on either 16 October, 30 October, 13 November or 25 November 1989. Two groups received single implants on 16 October and 25 November or 13 November and 25 December. The seventh group was an untreated control. Total down length in all treated groups was greater than the control (p<0.005). The goats treated on 16 October had the greatest response to melatonin and produced a 45% longer down fleece than the controls. The first fleece (16.8

The New Zealand Society of Animal Production - After the Jubilee - Nicol AM (Proceedings of the New Zealand Society of Animal Production, 1992)
Rib-eye muscle (M. longissimus lumborum) area (REA) and depth (B) at the 12th rib were ultrasonically measured on 89 ram lambs from 3 sire breeds. The lambs were then slaughtered and these live measures plus carcass weight were evaluated as predictors of the corresponding carcass measures and the following two measures of muscling, based on four muscles surrounding the femur bone and the femur itself: 1. Muscle:Bone ratio (M:B), and 2: Muscularity (MUSC), defined as an index of muscle depth (square root of the weight of the four muscles per unit femur bone length) relative to a skeletal dimension (femur length). Prediction of carcass REA and B from ultrasonic REA and B, after adjusting for carcass weight, was more effective for B (partial r=0.40) than REA (partial r=0.18). The main problems with prediction arose with higher values (B>33mm), when ultrasonic values underestimated actual carcass values. REA and B (ultrasonic live and direct carcass) significantly (p<0.001) improved the prediction of MUSC or M:B over carcass weight alone, but did not account for the highly significant (P<0.001) breed effect on these traits. It is concluded that ultrasonic and carcass measures of REA and B provide useful but limited information on lamb leg muscularity.

Nutrient supply for lamb growth from Grasslands Puna chicory (Cichorium intybus) and Wana cocksfoot (Dactylis glomerata) - Komolong K; Nicol AM; Poppi DP; Fraser TJ; Kirsopp S (Proceedings of the New Zealand Society of Animal Production, 1992)
The long-term success of any recording scheme depends on access to a genetically-structured database of performance records. Ram breeders in New Zealand have indicated preference for a system providing within-flock breeding value prediction via on-farm personal computers or through commercial bureaux on a regional level. This paper describes recent developments in industry structure in relation to animal evaluation and access to field data for research. Ram buyers, breeders and extension agents all benefit from consistent techniques for calculating and summarising the breeding worth of animals. The within-flock methodology prototyped in Animalplan has now been used to form the basis of a "genetic engine", available under licence, for incorporation into commercial programmes with database and reporting capabilities. Across-flock genetic evaluation (e.g. sire reference analyses) may require access to information from a number of distributed databases. A national identification system which recognises animals used in flocks other than their birth flock is re-requisite to analysis. The National Database has been initiated to ensure the integrity of data and to safeguard such pedigree and performance records for a wide variety of purposes. It will be updated annually to provide a single source for across-flock Best Linear Unbiased Prediction (BLUP) evaluation. The provision of the National Database ensures continued access to field data for animal breeding and other applied research. Genetic development of the scheme will come from improved specification of the production model (e.g. new traits and indicators of non-genetic effects) and from improve statistical approaches (e.g. BLUP and estimates of distributed parameters), all requiring access to and analysis of large bodies of genetically-structured field data.

Nutritional effects on the calpain system in skeletal muscle of sheep - Thomson BC; Oddy VH; Sainz RD (Proceedings of the New Zealand Society of Animal Production, 1992)
Deer are unique among New Zealand's farmed ruminants in the existence of hybridising species and subspecies which exhibit major differences in physiology and production traits. We used protein electrophoresis to examine genetic differences between two farmed deer species with fertile hybrids:red deer (Cervus elaphus) and Pere David's deer (Elaphurus davidianus<?I>) (in both species 2n=68). Fixed differences between the species were found for 19 proteins. A further 3 proteins were polymorphic in red deer but not in Pere David's deer. Using the present techniques, segregation of 17 of the protein differences between the species could be confirmed in a backcross pedigree to red deer. The large number of genetic markers segregating in backcross hybrids make them an excellent resource for gene linkage mapping among genetic markers and for experiments which examine the relationship between genetic markers and quantitative traits.

The nutritive value of Lotus for sheep - Waghorn GC; Shelton ID (Proceedings of the New Zealand Society of Animal Production, 1992)
A large-scale screening operation over two seasons by Landcorp Farming Ltd has established a terminal sire-breeding programme for sheep. Within the North and South Islands, screened hoggets were transferred to Huirimu Station and Kepler Station respectively. In 1989, 2,046 ewe hoggets (0.8%) were screened on liveweight from 248,500 animals in 114 flocks. Mean pooled population weight (adjusted to 18 December) was 43.2

Oestrus synchronisation and oestrus detection in Swamp Buffaloes (Bubalus bubalis) - Hill FI; Knight TW; Death AF; Wyeth TK; Ridland M (Proceedings of the New Zealand Society of Animal Production, 1992)
Selective mating of Perendale sheep for increased or reduced susceptibility as lambs to an experimental challenge with Haemonchus contorus commenced in 1986. Four years later changes were assessed by monitoring faecal nematode egg count (FEC) in ewes and their progeny. In the absence of drenching, mature flock ewes were given 7000 infective larvae of H. contortus and 3000 larvae of Trichostrongylus colubriformis in mid May 1990 after mating. FEC were monitored at regular intervals during pregnancy and 4 times during the periparturient period. Ewe and ram lamb progeny were faecal sampled on 5 occasions between weaning (November 1990) and May 1991. Lambs were drenched at most sampling dates. All stock were grazed across pasture contaminated previously with mixed parasite populations. Adult ewes selected as lambs for Resistance (low FEC) shed fewer eggs than Susceptible (high FEC) line ewes throughout pregnancy, 2 weeks pre- and 3, 6 and 9 weeks post-parturition. At the periparturient peak, approximately 3 weeks after lambing, Low FEC line ewes maintained FEC which were only 25% of those in the High FEC line. Lambs from the Low FEC line had significantly lower FEC than their High counterparts on 3 of 5 sample dates (P<0.01). At the final sample date (30 April 1991), there was a 10-fold difference in mean FEC between extreme sire groups. Bulked faecal cultures demonstrated that Haemonchus and Trichostrongylus were the dominant genera.

A pilot evaluation of shedding sheep breeds compared with non- shedding breeds for susceptibility to nematodes and flystrike - Litherland AJ; Sorenson E; Niezen J; Bishop D (Proceedings of the New Zealand Society of Animal Production, 1992)
The effects of ovine placental lactogen (oPL) on wool follicle development were examined in chronically catheterised singleton Dorset foetuses. From days 122 to 136 of gestation, five foetuses were infused intra-arterially with purified oPL (1.2 mg/day) in a carrier medium consisting of sterile physiological saline plus 15% plasma from non- pregnant ewes while another five were infused with carrier medium alone. Foetal arterial plasma concentrations of oPL were increased six-fold by the infusion compared with those in controls. Foetuses were euthanased on day 136 of gestation and skin samples excised from the midside for histological examination. Treatment of foetuses with oPL did not influence primary follicle density but reduced the ratio of immature secondary follicles to primary follicles (Control, 1.22 vs oPL-treated 1.01, Pooled SE = 0.06, P=0.06). These data provide the first evidence that follicle development in the lamb may be regulated by ovine placental lactogen.

Precalving nutrition of heavy two year old Angus heifers weighing 415 kg at calving - Pleasants AB; Barton RA (Proceedings of the New Zealand Society of Animal Production, 1992)
A short term grazing trial was conducted on a central Taranaki dairy farm to study the effects on milk production of regular light dressings of nitrogen fertiliser (N), when compared to a single heavy application. Fifteen paddocks were allocated to each of two treatments. Both treatments consisted of 50 kg N/ha applied as either a single heavy application (50 kg N/ha) on 10 September (50x1 treatment), or frequent light applications (10 kg N/ha), applied progressively from 10 September directly after the following 5 grazings (10x5 treatments). Grazing of herd alternated between the two treatments with 6 paddocks of one treatment being grazed for 4 consecutive days. Total milksolids (MS) production data was obtained for days 3 and 4 of each grazing period. Total net herbage accumulation from August to mid-January was similar for the two treatments even though there was a difference in the pattern of accumulation. The 50x1 treatment resulted in 28% higher net herbage accumulation between 12 November and 11 January. Botanical composition of the pastures in September, November and December indicated that 50x1 treatment increased the ryegrass content in November. Total MS production was 400 kg MS/ha between 1 October and 10 January for both treatments. The monthly MS production differences between the treatments were small. The results show there to be no advantage in terms of MS production to light regular applications of nitrogen fertiliser when compared to a single heavy application.

Production, Economic Performance and Optimum Stocking Rates of Holstein-Friesian and Jersey Cows - Ahlborn G; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1992)
The present New Zealand export lamb carcass classification system places carcasses into groups differing on average in fat (and meat) proportion (e.g. YM=20.6% fat, PM=23.8% fat, TM=27.0% fat and FM=28.2% fat). There is, however, considerable overlap in fat proportion between adjacent fatness classes. A comparison of the present mainly visual assessment system (one grader) with one based solely on measurement has shown that the objective systems investigated to date do not bring any major improvements in terms of sorting carcasses on the basis of composition. However, other advantages associated with an objective system, including the ability to sort out carcasses of any desired fatness range which may differ from current specified class ranges, makes the introduction of an instrument measurement based system extremely likely in the near future. As yet, a satisfactory instrument for this purpose has not been identified.

The reduction of cell division rate in wool follicles by noradrenaline - Scobie DR; Hynd PI; Setchell BP (Proceedings of the New Zealand Society of Animal Production, 1992)
A field trial at Flock House over a three year period (July 1989 - March 1992) compared the performance of grazing bulls alone at three stocking rates (3.0, 3.7 and 4.5 bulls/ha) with grazing bulls at 3.0 bulls/ha with an increasing stocking rate of goats (3, 7 and 13 Angora does/ha). The respective stocking rates in stock units (su/ha) for the six respective treatments from bulls alone at increasing stocking rate to bulls with goats at increasing stocking rate of goats were 15, 19, 23, 18, 21 and 26 su/ha respectively. Weaner bulls were brought onto the farmlets in November each year and all rising 2 year bulls were sold off the farmlets over January to April at 18-21 months of age. Bull growth rates were significantly depressed by increasing the stocking rate of bulls but were unaffected by an increasing stocking rate of does. Bulls in the bull/goat treatment at 26 su/ha grew at a similar rate of bulls but were unaffected by an increasing stocking rate of does. Bulls in the bull/goat treatment at 26 su/ha grew at a similar rate to bulls alone, stocked at 15 su/ha. Goat performance; kidding, kid fleece weight and doe fleece weight were not affected by goat stocking rate. However at the high doe stocking rate, kid liveweight at weaning and doe liveweight (March) was reduced (P<0.01 and P<0.05 respectively). Stocking rate treatments had little effect on the economic farm surplus (variation between $680/ha for the least profitable to $730/ha for the most profitable treatments). However with a more buoyant mohair market and a more robust/productive strain of Angora goat ie. the Zimbabwe Angora, it is assumed that bull/goat system would be more profitable than bulls alone. Although goats were not complementary to bull beef production they were also not competitive with bulls over the stocking rates investigated.

Reproduction in flocks selected for and against lamb faecal egg count - McMillan WH; Hall DRH; Watson TG (Proceedings of the New Zealand Society of Animal Production, 1992)
The calpain system consists of two enzymes and their endogenous inhibitor, calpastatin, and is involved in the breakdown of myofibrillar protein in skeletal muscle. We have investigated the relationship between the calpain system and protein degradation in sheep under three different feeding regimes. Calpain were separated from fresh muscle using a DEAE-Sephacel ion exchange column. Calpain I and calpastatin activities were higher in the restricted group than in the ad- libitum group. Fasting increased calpastatin but had no effect on the calpain I activity. There was a positive relationship between the calpastatin : calpain I ratio and protein degradation and a negative relationship with calpain I. This result is at variance with the idea that calpain I activity limits the rate of protein degradation.

Reproductive performance and liveweight in Romney sheep selected for fleece weight and a control flock - Wuliji T; Dodds KG; Andrews RN; Turner P; Wheeler R (Proceedings of the New Zealand Society of Animal Production, 1992)
Genetic and nutritional factors that cause marked changes in wool growth influence the content (

Responses to selection for wool staple strength in Romney sheep - Bray AR; Smith MC; Woods JL; Baird DB (Proceedings of the New Zealand Society of Animal Production, 1992)
In a series of studies, relationships between herbage allowance (as measured by sward surface height (SSH), herbage intake (measured by intraruminal chromium controlled release capsule) and production were assessed in continuously stocked winter (June)- and spring (August)- lambing pregnant and lactating ewes. At SSHs of 2.8, 4.0, 7.1 and 8.5 cm, organic matter intakes (OMI) of winter-lambing ewes in the last month of pregnancy were 1.4, 1.7, 1.6 and 1.9 (Pooled SE = 0.1) kg/d (P<0.05), respectively. Ewe liveweight gain over the last month of pregnancy increased with SSH but there was no effect of SSH on lamb birthweight or ewe midside wool growth. Similarly, pregnant spring- lambing ewes had OMI of 1.4, 1.7, 1.8 and 1.9 (PSE = 0.1) kg/d (P<0.05) at SSHs of 2.7, 4.0, 5.9 and 7.8 cm, respectively and ewe liveweight gain increased with SSH but there was no effect of SSH on ewe wool growth or lamb birthweight. Results suggest that both winter- and spring-lambing ewes can tolerate SSH below 3 cm during late pregnancy without detrimental effects on lamb or wool production. Winter-lambing lactating ewes (first two months of lactation) had OMI of 1.8, 2.3 and 2.5 (PSE = 0.1) kg/d (P<0.05) at SSHs of 2.6, 4.4 and 7.8 cm respectively. Sward height did not influence ewe wool production or lamb growth but ewes on the 2.6 cm sward lost 8-10 kg more liveweight during lactation than those on the 4.4 and 7.8 cm swards. Spring- lambing ewes had OMI of 1.8, 2.0, 1.9, 2.0 and 2.0 (PSE = 0.3) kg/d (P<0.1) at SSHs of 3.5, 5.0, 6.0, 7.0 and 8.5 cm, respectively. There were no effects of SSH on ewe wool growth or lamb growth but ewe liveweight loss was greatest at low SSH. Results are discussed in the context of feeding recommendations for winter- and spring-lambing ewes.

A review implicating a two compartment model for the processes of cell division and differentiation in the Wool Follicle - Scobie DR; Woods JL (Proceedings of the New Zealand Society of Animal Production, 1992)
The effects of injecting GnRH at mating and of single vs multiple matings on the conception rate in alpacas were investigated in two experiments. In Experiment 1, 33 low liveweight (48.4

The role of computer software in the feeding of farm livestock - Brookes IM; Parker WJ; Gray DI (Proceedings of the New Zealand Society of Animal Production, 1992)
Romney ewes with consistently high (H, n=5) or low L, n=5) seasonal changes in wool growth and with differences in ovulation rate and the onset of anoestrus, were blood sampled every 30 min for 24 h at the winter and summer solstices and at the spring and autumn equinoxes. Plasma samples were assayed for melatonin by direct radioimmunoassay. Mean melatonin levels were higher during the hours of darkness than during daylight at all sampling times. However, the ratio between day- and night-time melatonin levels tended to be smaller in spring (1.8) and summer (1.5) than autumn (2.9) and winter (1988 - 3.8; 1989 - 4.1). There were no significant differences between H and L ewes in mean melatonin concentrations during daylight or darkness at any of the seasons. There was however, considerable variation between individual ewes in the diurnal pattern of melatonin secretion in spring and summer. The high levels of melatonin usually associated with darkness were sometimes found during the day. These disrupted patterns of melatonin secretion occurred in all ewes at one or other of these two seasons. The results suggest that during anoestrus, melatonin profiles may differ from the normal pattern of secretion that is aligned to photoperiod.

Seasonal effects on the efficacy of intravaginal CIDR devices for oestrous synchronization of farmed fallow deer (Dama dama) - Morrow CJ; Asher GW; Smith JF; Jabbour HN; Mulley RC; McLeay LM (Proceedings of the New Zealand Society of Animal Production, 1992)
The production of the Woodlands high prolificacy flocks was compared to industry control animals. Effects of the Inverdale gene (FecX

Sheep growth rates under Pinus Radiata - Hawke MF; Percival NS (Proceedings of the New Zealand Society of Animal Production, 1992)
Preliminary results are given of a study of follicle differences between a progeny-tested fleeceweight (FWT) line of sheep and a control (CLT) flock which was conducted during winter. Measurements using immunocytochemistry and image analysis on skin biopsies were based upon the use of intracutaneously administered bromodeoxyuridine (BrdU) to assess the replicating cell population in wool follicles. The FWT animals showed a significant advantage over the CLT animals in number of replicating cells, papilla length, papilla area and area of replicating zone in the follicle bulb. There were no significant differences between the flocks in the ratio of primary to secondary follicles or in the number of active follicles. The mitotic density was similar in both flocks. The greater productivity of FWT sheep appears to be accounted for by a larger proliferative zone rather than a higher cell replication rate.

Slimming diets for overfat lambs - Cruickshank GJ; Muir PD; MacLean KS (Proceedings of the New Zealand Society of Animal Production, 1992)
Wool staple strength was determined in 2120 Romney ewes from 12 sources and 242 Romney rams from 3 sources between 1986 and 1988. Positive, negative and random selection formed High Strength, Low Strength and Control lines, each with 80 ewes and 10 sires. Since 1989 ewe and ram replacements have been selected from within the lines and the number of breeding ewes per line increased to 100. Staple strength was 25% greater in the High Strength line and 15% lower in the Low Strength line than in the Control line when fleeces of hoggets born in the selection lines from 1986 to 1989 were compared (P<0.01). Positively correlated with the staple strength response were responses in staple length, fibre diameter, clean fleece weight and fibre length after carding. The major effect to date of selection for increased staple strength has been to enhance wool growth, with the consequent increase in fibre diameter contributing to the improvement in staple strength. The increase in both the strength and length of staples will have contributed to the increase in fibre length after carding. These preliminary results demonstrate that direct selection for staple strength has been successful. The staple strength response and associated responses in wool production and wool characteristics were of benefit to both producers and processors.

Subcutaneous fat distribution as assessed by ultrasound in Border Leicester and Dorset Down ewe hoggets - Deaker JM; Young MJ (Proceedings of the New Zealand Society of Animal Production, 1992)
A study of growth and venison production from weaner red deer grazing pure "Pawera" tetraploid red clover (RC) or conventional perennial ryegrass/white clover (PRG) pasture was conducted, with the objective of attaining a minimum slaughter liveweight (92 kg; 50 kg carcass) by 12 months of age in the stags. Ten weaner red deer stags and 10 weaner red deer hinds were rotationally grazed on either RC or PRG pasture. In autumn and spring, forage allowances were respectively, 7 kgDM/h/d and 8 kgDM/h/d. In winter, the animals from both groups were grazed together on PRG pasture, at a residual dry matter of 1100 kg/DM/ha; 0.5 kgDM/h/d of meadow hay was also provided. Liveweight gains of RC and PRG stags were respectively 263 vs 192 g/d, 101 vs 106 g/d and 362 vs 341 g/d during autumn, winter and spring. With hinds, the liveweight gains of RC and PRG groups were respectively 198 vs 173 g/d, 52 vs 53 g/d and 242 vs 218 g/d during autumn, winter and spring. Animals grazing RC pasture had significantly higher liveweight gain during autumn (p<0.01), but not in winter and spring. At one year of age, stags grazing RC were 7 kg heavier and hinds 3 kg heavier than animals grazing PRG pasture. Animals grazing RC pasture had higher voluntary feed intake (VFI) in both autumn (p<0.10) and spring (p<0.001), than animals grazing PRG pasture. All stags grazing RC pasture reached the minimum slaughter liveweight by one year of age, compared to 75% grazing PRG pasture. Stags that had grazed RC produced heavier carcass weights (59.9 vs 54.5 kg, p<0.01), and had higher carcass dressing percentage (55.3 vs 53.2%, p<0.01). RC has potential as a special purpose forage for the growth of weaner red deer.

Suppression of secondary wool follicle development by administration of placental lactogen to ovine foetuses - Wickham GA; Schoknecht PA; Currie WB; Bell AW; McCutcheon SN (Proceedings of the New Zealand Society of Animal Production, 1992)
No abstract supplied.

A terminal sire breeding programme based on screening for hogget liveweight - Nicoll GB; Alderton MJ; Annandale DD; Coleman ID; Grimwood TJ; Thomson JA (Proceedings of the New Zealand Society of Animal Production, 1992)
Eighty mature fallow deer does were allocated to four treatment groups (n+20) for which oestrous synchronization treatment consisted of intravaginal insertion of single CIDR devices for 14 days and prostaglandin administration on days 0 and 10 of device insertion. Treatment groups were staggered successively by 7-day intervals from early March to late May, the period spanning the natural mating season (rut). Observations to determine the onset of oestrus were performed 24-72 hours after CIDR device withdrawal and blood samples were collected four times during insertion and then every 2 days, for 14 days, from CIDR device withdrawal. Plasma samples were analysed for progesterone concentration to determine luteal development. A group of untreated contemporary control does were allowed to mate naturally to crayon-harnessed bucks to determine the period of the 1990 natural rut. Oestrus and ovulation were detected on 69% and 80% of occasions respectively following CIDR device withdrawal, with ovulation following oestrus on 98% of occasions. Ovulation not preceded by observed oestrus, probably representing silent ovulations, occurred early in the breeding season. There was complete failure of response, in terms of does exhibiting oestrus increased from 0-10% to 89-100% with the greatest coinciding with the onset of the natural rut. In addition, the mean interval from CIDR device withdrawal to onset of oestrus tended to decrease from between 71-88h to 47-63h and oestrous synchrony improved progressively during the trial. The efficacy of CIDR devices in synchronizing oestrus and ovulation in fallow deer does is clearly influenced by timing of treatment relative to the natural breeding season of the herd.

Testis size and endocrine parameters in rams as predictors of aseasonality in their daughters - Xu ZZ; McDonald MF; McCutcheon SN; Blair HT (Proceedings of the New Zealand Society of Animal Production, 1992)
Overseas data suggest that feeding low energy/high protein diets can increase carcass weight (and muscle mass) while reducing fat content. The potential application of this technique to maximise the returns from overfat lambs in New Zealand was studied. One hundred and sixty ewe lambs, assessed as being overfat, were allocated on a liveweight basis to one of seven treatment groups. These comprised an initial slaughter group, 2 groups offered pasture at approximately maintenance allowance, 2 groups offered pasture at approximately half maintenance plus 200g/d of a high protein pellet and 2 groups held on a bare paddock and offered ad lib straw plus 200g/d of a high protein pellet. One group from each treatment was slaughtered after 3 weeks and the second after 5 weeks of controlled feeding. Liveweight change, carcass weight and carcass fatness were monitored. All groups lost liveweight (88-195 g/d) and estimated carcass weight (37-89g/d) over the experiment. Corrected to a common carcass weight of 15.25kg decreased GR from 11.6mm for the initial slaughter group to 9.7 and 9.2mm after 3 and 5 weeks, respectively of maintenance pasture feeding. Corresponding GR's of the supplemented groups were 9.3mm (both groups) after 3 weeks and 8.1 and 7.5mm after 5 weeks for straw and pasture based diets respectively. Supplementation with a high protein diet was effective in reducing carcass GR measurement after 3 weeks of supplementation with a further decrease after 5 weeks. However, unsupplemented lambs also showed a decrease in GR after 3 weeks, which was not significantly different from supplemented lambs. The length of feeding required to effect a change negated the advantage of decreased GR, although economic returns could be achieved if the pellets were more readily accepted.

Timing of the LH peak and ovulations in superovulated Coopworth ewes synchronised with progesterone-containing CIDR devices - Thompson JG; Simpson AC; James RW; Tervit HR; Asher GW; Peterson AJ (Proceedings of the New Zealand Society of Animal Production, 1992)
A replicated trial with 4 stock rates of 'wet' ewes (9.0, 10.5, 12.0, 13.5 sheep/ha) and 4 stocking rates of 'dry' ewes (11.0, 13.5, 16.0, 18.5 sheep/ha) was established at the DSIR Grasslands 'Ballantrae' Hill Country Research Station to enable hill country farmers to make informed decisions as to the economics of farming breeding or unmated ewes. Stocking rate had a large effect on liveweight throughout the year with the greatest effect being in winter. Mean weaning weight of lambs was 25.4 kg at 9.0 ewes/ha and 19.7 kg at 13.5 ewes/ha. Dry ewes grew more greasy wool/ha than wet ewes (P<0.05). Greasy wool production ranged from 41.6 kg/ha at 9 wet ewes/ha to 81 kg/ha at 18.5 dry ewes/ha. At 13.5 sheep/ha dry ewes grew 28% more greasy wool than wet ewes which reared 1.2 lambs to weaning. November/December fleece weight/ha was unresponsive to increasing stocking rate for both wet and dry ewes (P<0.01). November/December fleeces were 18.6% heavier from ewes in paddocks having a sunny aspect than in paddocks with a predominantly shady aspect (P<0.001). Slowest wool growth occurred during August, being 5.3 to 8.3 mm/month and maximum wool growth occurred during January within the range 17.3 to 18.5 mm/month.

The use of farm computers in animal management - Nuthall PL (Proceedings of the New Zealand Society of Animal Production, 1992)
A dose-response curve for ovulation rate in Merino ewes homozygous for Booroola FecB gene was generated by injecting PMSG at dose rates increasing from 3300-1200iu in 100iu increments (n=8-13 per group). PMSG was administered, at a concentration of 1000iu/ml in a saline carrier, as a single injection 15 days after the withdrawal of intravaginal progestagen sponges. An additional 20 control ewes were injected with 1ml of saline. The mean lifetime ovulation rate (LO) was calculated for each ewe from data collected for up to three years prior to the study. In individual ewes, a "response" to PMSG was defined as an ovulation rate at least 4 standard deviations (flock mean SD 0.87) greater than LO. Using this arbitrary value, no animals responded at doses below 500iu and less than 50% responded at 500 and 600iu. Above 800iu 75-100% of ewes in each treatment group responded. When log ovulation rate was regressed against dose of PMSG there was a highly significant dose-response (P<0.001, RSD 0.512). Using a subjective assessment of changes in ovarian morphology it was observed that >/=70% of ewes given 1000iu or more of PMSG showed over- stimulation of one or both ovaries. There was no apparent carry-over effect of PMSG at the oestrous cycle following treatment.

The use of protein polymorphism and DNA fingerprinting to solve complex pedigree problems in deer - Brief Communication - Tate ML; Dodds KG; McEwan KM; Buchanan FC; Swarbrick PA (Proceedings of the New Zealand Society of Animal Production, 1992)
In a study of seasonality of reproduction, 4 pubertal red deer hinds were monitored for live weight and plasma hormone concentrations from December 1987 to October 1988 (i.e. 12-22 months of age). On 7 occasions blood samples were collected every 20 minutes for 4 h to monitor secretion of luteinising hormone (LH) and response to an i.v. injection of 2

The value of ultrasound in assessing the leg muscling of lambs - Ward BG; Purchas RW; Abdullah AY (Proceedings of the New Zealand Society of Animal Production, 1992)
Faecal worm egg counts (FEC) were recorded on 779 lamb progeny in a performance recorded flock in Northland during summer-autumn 1990 to determine breed and sire variations. Progeny were ram lambs born in 1989 representing 4 Perendale, 4 Romney and 7 cross-bred sires. The study protocol was that the lambs remained undrenched until the mean FEC of representative 'monitors' reached 1000-1500 eggs/g. Then all stock were faecal sampled, drenched and the protocol repeated. Full samplings occurred on 12 February (FEC1) and 12 March (FEC2). All animals grazed as one mob throughout the programme. There were significant variations within and between breeds in FEC. Perendale and Crossbred lambs had significantly lower faecal egg outputs than Romneys on both occasions (FEC1=3560, 4073, 4757; FEC2=2535, 3242, 3737, respectively). One possible explanation of the results is that Perendales selectively avoid parasite contamination on pasture through differences in grazing behaviour. Alternatively, they may have consumed less pasture and larvae because they were lighter. If these are not the cases these data suggest that Perendales in this flock may be more resistant to internal parasites.

Wool growth and elemental composition - Lee J; Bray AR; Grace ND (Proceedings of the New Zealand Society of Animal Production, 1992)
Six Merino wethers were used to graze six box-grown genotypes of subterranean clover in a Latin square design. Each animal was offered 2 replicates of each genotype and permitted to graze 70% of the sward on offer. The amount eaten was recorded at each grazing and video recordings were used to record each sheep's grazing behaviour. There were genotype differences in the rate of intake of fresh feed (g/min) with Clare (79.3 g/min) being eaten faster than the other genotypes while Trikkala (67.1 g/min) was eaten faster than both Geraldton (53.0 g/min) and Dinninup (54.9 g/min). Similarly bite rate and dry matter (DM) per bite (bite weight) were significantly related to genotype. With Dinninup the rate of intake and DM per bite were less than expected from the measured sward characteristics while differences in sward height accounted for most of the differences recorded with Clare (20 cm tall) and Geraldton (8 cm tall). The results indicate differences in the intake response of sheep to different genotypes of subterranean clover. Possible reasons for these differences are discussed.

Wool production from wet and dry ewes on southern North Island hill country - Betteridge K; Lambert MG; Devantier BP; Budding PJ; Costall DA; Fletcher RH (Proceedings of the New Zealand Society of Animal Production, 1992)
Two trials were conducted which examined the effect of duration of CIDR

alpha-Lactabumin - The milk manipulator's dream - Wilkins RJ (Proceedings of the New Zealand Society of Animal Production, 1991)
The importation of 100 alpacas from Chile in 1989 has enabled some preliminary observations to be made on the performance of these animals under farming conditions in Otago. After one year the adult female liveweights (70.8-72.8 kg) exceeded that of alpacas farmed in South America. Cria showed high growth rates (176 gm/day) to weaning at 5 months of age. Sixty two cria were born and their survival to 7 months of age was high (92%). Only 22% of females had cria following spring mating but a more successful autumn mating resulted in 61% pregnant. Adult females clipped 1.7 kg and males 2.8 kg of fibre. The fibre diameter from females averaged 28.8 microns and from males 30.6 microns. Nine month old cria clipped 1.7 kg of fibre with a mean diameter of 23.4 microns. These preliminary data indicate that alpacas are adapting well to this new environment, but as in South America, there are problems of low fertility.

Alternative and supplements to pasture for growing lambs in winter - Bray AR; Moss RA; Burton RN (Proceedings of the New Zealand Society of Animal Production, 1991)
The Wairunga flock was established in 1956. It has since been selected for production traits and, recently, also for 'disease' traits (resistance to footrot, dags and internal parasites). Records of weaning weight, autumn weight, winter weight, faecal egg count (FEC) and fleece weight have been collected on ewe and ram lambs from the 1987- born crop onwards, in a management programme which involved withholding anthelmintic drench for a monitored period in autumn. Dag scores have also been taken at the time of faecal sampling from the 1988-born crop onwards. Experiences already show that there is keen interest from ram buyer clients in 2-tooth rams that have grown without a drench. Results show significant potential savings in numbers of drenches on weaned lambs, and large differences among sire groups in the parasite susceptibility of progeny groups. Because of the need to withhold drenches, a major change in the whole concept of ram breeding and performance testing will be required by ram breeders and their clients before much progress can be made in breeding for resistance to internal parasites.

Analysis of lamb schedules and relative economic values of lean and fat - Waldron DF; Clarke JN; Rae AL (Proceedings of the New Zealand Society of Animal Production, 1991)
A model is constructed to give the probability of conception conditional on the previous calving date in a herd of Angus beef cows. The parameters of the model are the anoestrous period following calving, the length of the oestrous cycle (both independent random variables having normal probability distributions), and the conception rate at each oestrus occurring within the mating period. The anoestrous period is assumed to depend linearly on the calving date. The observed calving distributions of 10 consecutive years in a beef cow herd were used in the model to estimate the optimum herd conception rate for the parameters "anoestrous period" and "regression between anoestrous and calving date". A conception rate at each oestrous during mating of 0.7 was assumed. Anoestrous period was constrained by experiment to between 50 and 90 days. The regression between anoestrous and calving date was constrained to between 0 and -0.5 days per day. These constraints constituted a non-linear programming problem. The optimum values for the anoestrous period under these conditions lay between 60 and 70 days for the 10 years of data analysed. It is shown that the anoestrous period has very little effect on herd in calf rate below 70 days in the calving distributions considered. It is suggested that resources should not be used to reduce the anoestrous period below 70 days. The anoestrous period tended to have a greater effect on herd conception rate if less than 90% of the herd had calved before day 40 of the calving period, and the anoestrous period was longer than 70 days. Beginning mating 7 days earlier generally increased the herd conception rate by about 1% over the 10 years considered.

Antibody-mediated enhancement of growth hormone activity: application to animal production - Aston R; Holder AT; Rathjen DA; Trigg TE; Moss BA; Pell JA (Proceedings of the New Zealand Society of Animal Production, 1991)
In addition to advantages offered to the lamb trade by the new sheep breeds they also offer opportunities to the wool industry. The influence of new breeds imported by Lamb XL on lamb and hogget wool production and characteristics was examined for Texel, Oxford Down, Whiteheaded Marsh and Finnish Landrace crossbreds compared with Romneys. Fleece weights were similar for the Oxford Down, Whiteheaded Marsh and Romney crosses but Texel crosses had a 12% reduction in hogget fleece weight. Texel and Oxford Down cross hoggets produced wool with high bulk and staple strength compared to the Romney cross hoggets. These characteristics are currently of special interest in the wool industry, with premiums existing for bulk and anticipated in the near future for staple strength. There were no practical differences in other wool characteristics between Romney, Texel, Oxford Down and Whiteheaded Marsh cross hoggets including fibre diameter, yield, colour, vegetable matter contamination and position of break. Finnish Landrace crosses produced lighter, finer fleeces. However half Finnish Landrace crosses are unlikely to be used in farming systems and reductions in fleece weight will be lower in the anticipated quarter or eighth Finnish Landrace crosses. Lamb and hogget wool production and characteristics from the exotic crossbreds compare favourably with New Zealand Romneys and offer increases in wool production compared to traditional terminal sires.

Are yearling heifer mating and more productive beef cow breeds a worthwhile use of winter feed? - McMillan WH; McCall DG (Proceedings of the New Zealand Society of Animal Production, 1991)
A computer software package (REVGAIN) is being developed to integrate closely with Animalplan. It assists breeders and their advisers to derive relative economic values and selection criteria to suit their breeding programme. For farmers buying flock rams REVGAIN derives relative economic values for their individual commercial flock, and hence the sort of breeder from which to buy rams. Using specific production levels, prices, and costs for the producers' or breeders' situation, together with the corresponding Animalplan phenotypic and genetic parameters, the software calculates relative economic values that will lead to maximum economic progress in the breeding goal. It also estimates the change in each character that will occur from a standard amount of index selection. By comparing different economic outcomes from changing product prices, physical inputs or genetic responses, users derive the policy that is most appropriate to their particular situation.

Artificial insemination and synchronised natural breeding in Red deer - Fennessy PF; Mackintosh CG; Shackell GH; Whaanga AJ (Proceedings of the New Zealand Society of Animal Production, 1991)
The cold resistance of cashmere wethers in which cashmere had been harvested by shearing the while fleece, or by removal of down only through repeated hand combings, was studied at two ambient temperatures (10 C and 30 C) and two wind speeds (0 and 6 km/hr). Heat production was calculated from oxygen consumption measured over 24 hours, in 8 pairs of goats fed at 1.25 times maintenance level. In shorn goats, heat production increased by 50% during exposure to 10 C (compared with 30 C) while the corresponding increase for combed goats was only 9%. The interaction between the effects of the low temperature and the methods of fibre removal was significant (P<0.001). Similarly at 10 C, exposure to a wind of 6km/hr caused a larger increase in heat production in shorn goats than in combed goats; the interaction was significant (P<0.05). The data show clearly that the combed goats were considerably more resistant to cold conditions that the shorn goats.

Artificial insemination using the buck effect to partially synchronise cashmere does - Moore RW; Hall DRH (Proceedings of the New Zealand Society of Animal Production, 1991)
No abstract available

Autocrine control in milk production and mammary development - Wilde CJ; Addey CVP; Knight CH; Peaker M (Proceedings of the New Zealand Society of Animal Production, 1991)
Currently less than 20% of the lambs slaughtered in New Zealand each year for export are killed in the five months from July to November. The feeding of high grain content diets in feedlots, grain supplements at pasture, maize silage or forage legumes to increase lamb supply over this period is discussed. Grain-based feedlot diets, supplements of pea grain fed at pasture and lupin and tick bean forage produced lamb liveweight gains of 200 to 300 g/d, that compare with gains of up to 150 g/d expected at pasture. Effects on carcass leanness and meat taste were generally small. Although usually more expensive than pasture, other feeds can be at least as profitable when pasture is in short supply premiums are paid for lambs supplied in winter and spring.

Best linear unbiased prediction for across-flock/year breeding values - Garrick DJ (Proceedings of the New Zealand Society of Animal Production, 1991)
Three pasture types (Wana cocksfoot, Roa tall fescue, and Ruanui perennial ryegrass/Huia white clover) were ranked on short term rates of intake, measured using boxed turfs indoors and short grazing periods at pasture. In the first experiment 12 turfs of each pasture type were offered to each of 3 heifers indoors in a latin square design. In a second experiment at pasture, 3 heifers grazed each pasture type for a day again in a latin square design. Intake rate in the first experiment was estimated from pre- and post- grazing weight of turfs with correction for respiratory and evaporative weight loss. At pasture in the second experiment intake rate was the difference between pre and post grazing weight of the heifers corrected for insensible weight loss. Rankings of grass cultivars indoors and outdoors were similar even though animal and sward maturity differed. Intake rate of ryegrass/white clover was lower both indoors and outdoors than for Roa tall fescue or Wana cocksfoot (indoors 103 vs 131 and 148, and outdoors 65 vs 161 and 102 mgDM/kg/W/min). Bite weight (2.1 vs 2.7 and 2.8 mgDM/kgW) and bite depth (5.9 vs 6.4 and 6.7 cm) for ryegrass/white clover indoors were lower than for tall fescue or cocksfoot. Allocation/intake relationships derived for ryegrass/white clover may not be applicable to other pasture species.

Breeding for disease resistance - some historical perspectives, problems and prospects - Baker RL (Proceedings of the New Zealand Society of Animal Production, 1991)
Red deer stags received a series of immunisations against LHRH with the aim of suppressing the reduction in growth normally associated with the rut, but without affecting carcass fatness. Immunisations commenced at 10 months of age (September), including a series of either early (October) or late (November) booster immunisations. The immunisations produced antibodies to LHRH and delayed testes enlargement, with effects being greatest during summer (December- January). Liveweight changes were similar in the late booster and control groups. Mean liveweight declined during the rut (April and May) in all groups. However, stags that received the early booster were significantly heavier (P<0.05) than the other two groups in October (11 months old) and from February to October of the following year (15-23 months old). Twenty four hours prior to slaughter (October), mean (

Brief Communication - Susceptibility of the breeding ewe to parasitism - McAnulty RW; Familton AS; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1991)
Genetic and phenotypic parameters were estimated for some components of cashmere production using data obtained from goats born in 1987 and 1988 from flocks participating in a sire reference scheme. A total of 33 sires and 841 progeny were included in the analysis. Heritability estimates of weaning and yearling liveweights from univariate restricted maximum likelihood (REML) analyses were 0.14

Bulk and its structural basis: A review - Stobart RH; Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1991)
A case farm study of a once-bred heifer system on hill country using a spreadsheet simulation model was undertaken. Results of the feed budge and financial data of the once-bred system were compared with bull beef, 18 month heifer finishing and traditional breeding cow policies. The once-bred heifer system generated a gross margin of $48.26/s.u. compared with $42.50/s.u. for a traditional breeding cow breeding system, $31.70/s.u. for the 20 month heifer finishing and $52.80/s.u. for a bull beef system. The once-bred heifer system produced 314 kg carcass/ha, the breeding system cow 197 kg carcass/ha, the 20 month heifer system 354 kg carcass/ha and the bull beef system 433 kg carcass/ha. The major factor affecting the profitability of the once- bred heifer system was schedule price. The best match of animal requirements and pasture growth for the once-bred heifer system was shown to occur for an October calving. This study suggests that sheep and beef farmers with traditional beef cattle policies could increase productivity by adopting a once-bred heifer beef production system.

Comparative wool production of Texel, Oxford Down, Finnish Landrace and Romney sheep - Dobbie JL; Sumner RMW; Clarke JN; Speedy PM (Proceedings of the New Zealand Society of Animal Production, 1991)
Two lines of Perendale sheep selected for an against loose wool bulk as yearlings at hogget shearing were established at Whatawhata Research Centre in 1987. Each line consists of approximately 100 mixed age breeding ewes. At ewe hogget shearing in 1989 loose wool bulk of the selection lines differed by 5.2

A comparison between lamb drafters and the Phillips Fat Displacement Meter (PFDM) for predicting GR, hot carcass weight and class in live lambs - Kirton AH; Uljee AE; Mercer GJK (Proceedings of the New Zealand Society of Animal Production, 1991)
A fine wool index selection flock (I) was established by screening the Tara Hills Merino flocks in 1988 and 1989. The flock of 200 breeding ewes was formed with equal numbers of four age groups born in 1984 to 1987. A randomly sampled 160 ewes from the same population served as the Control (C). The greasy fleece weights of the I flock were 8.3% (P<0.001), 6.8% (P<0.001) higher than that of C flock in 1988 and 1989 respectively. Spring live weight (P<0.05) and yield (P<0.001) were significantly higher while fibre diameter (P<0.001) was significantly lower for I. Progeny hogget fleece weight, live weight and fibre diameter, however, differed insignificantly between flocks.

Computer software to increase the efficiency of the New Zealand sheep industry - Binnie DB; Clarke JN; Cooke AC; Johnson DL; Rae AL (Proceedings of the New Zealand Society of Animal Production, 1991)
Loose wool bulk has been identified as a desirable objective characteristic associated with superior end-product performance in many of the present uses of wool. These are specifically, improve appearance retention of carpets and improved insulation of knitting yarns and loose wool batts. Breeds have been shown to differ in their ability to produce high bulk wools. Loose wool bulk is strongly inherited in the adult fleece, it is not however expressed in the lamb fleece and subsequently cannot be used as a selection criteria until hogget shearing. Fibre crimp appears to be the major factor associated with bulk. Crimp formation in Merinos is related to follicle structure, cell mitotic activity and cellular differentiation within the follicle bulk resulting in the production of different cortical cell types. At this time it is not known if a similar situation applies to crossbred wool type sheep. The identification of a suitable measurable structural characteristic would facilitate the selection of high loose wool bulk crossbred wool type sheep at a young age.

Dairying in the south - McDonnell AM (Proceedings of the New Zealand Society of Animal Production, 1991)
Synchronised breeding systems involving 290 red deer hinds were investigated in 5 experiments with fixed-time laparoscopic artificial insemination (AI) following a synchronised oestrus and in 1 experiment with synchronised natural breeding. Experiment 1 involved an investigation of the potential for twinning; hinds were treated with PMSG and inseminated before (March 1) or during (April 12) the normal breeding season, with 29 and 40% respectively having multiple ovulations. There was no effect of AI date on pregnancy rate (0.80 and 0.71 respectively) but a greater proportion of hinds which had multiple ovulations. There was no effect of AI date on pregnancy rate (0.80 and 0.71 respectively) but a greater proportion of hinds which had multiple ovulations and had not been lactating in the previous season were twin- pregnant than hinds which had been lactating (0.19 and 0.62, P<0.05). In other experiments AI was performed using red (R; n=70), Canadian wapiti (CW; n=59) or CW x R hybrid (n=11) frozen-thawed semen with pregnancy rates of 0.67, 0.66 and 0.82 respectively. Fresh Pere David's deer x R hybrid semen gave a pregnancy rate of 0.61 (n=31). A pregnancy rate of 0.84 was recorded for the synchronised natural mating of (CW x R) males with red females (n=49). Overall 3% of the R pregnancies and 9% of the hybrid pregnancies failed to reach terms.

Development of a self-drafting system for oestrus ewes - Matthews LR; Uljee AE; Bremner KJ; Painting AM; Cate LR; Smith JF (Proceedings of the New Zealand Society of Animal Production, 1991)
The effect of nutrition on fibre growth cycles and medullation in skin of Angora goats was investigated by microscopy of transverse sections of hair follicles. Samples of skin and fleece were taken at regular intervals between August 1989 and August 1990 from non- reproducing does fed either maintenance (MPA) or ad libitum (HPA) pasture allowances. There were no differences in follicle activity between nutritional treatment groups for any of the 11 sample dates. Primary follicles grew and shed their fibres seasonally, with the main growth period from September to May and the mean nadir of 26

DNA variation among seven New Zealand sheep breeds - Sise JA; Montgomery GW; Hill DF (Proceedings of the New Zealand Society of Animal Production, 1991)
Karyotype analysis, used for screening chromosomal anomalies in humans and livestock, is being evaluated as a means of identifying sheep carrying the Booroola fecundity gene. This has involved comparing the chromosomes of metaphase spreads from animals heterozygous for the Booroola gene (FecB+) to screen for numerical or physical abnormalities between the chromosome pairs using Giemsa (GTG) banding. A number of anomalies have been observed from 18 of 3 FecB+ rams and 4 FecB+ ewes. The anomalies were spread throughout most chromosomes, but none were present in all karyotypes. No alteration in chromosome number was observed. These preliminary results suggest that the Booroola mutation is not the result of a major chromosomal alteration.

The effect of cow age and management of winter liveweight gain, liveweight at calving and subsequent effects on dairy production in a seasonal supply herd - Thomson NA; Barnes ML; Prestidge R (Proceedings of the New Zealand Society of Animal Production, 1991)
A trial was undertaken in which 11 meat company lamb drafters estimated the GR carcass fatness, hot carcass weight and carcass class on 26 live lambs. In addition the Phillips Fat Displacement Meter (PFDM) was used to estimate GR fatness these live animals. The average hot carcass weight of the lambs was 21.9kg and mean GR on the left and right sides were 14.2mm and 14.5mm respectively. The best two drafter estimates correlated more highly (0.89 and 0.83) than the PFDM (0.81) with lamb carcass GR (mm) on the left sides of these carcasses. On the right sides these two drafters correlations were respectively 0.91 and 0.84 while the PFDM correlation was 0.85. The correlations of the poorest drafter were 0.62 and 0.57 for the left and right sides, respectively. While the best drafters were accurate in ranking live lambs for fatness, in absolute terms all drafters underestimated GR on average by 2.2mm whereas the PFDM underestimated by 1.1mm on the left side and 0.8mm on the right. So for actually drafting lambs for slaughter, the PFDM is less likely to select lambs in the penalty payment ranges, or is more likely to select lambs before they reach these penalty fatness levels than the company drafters. These results highlight the need for drafter training courses with feedback on their results. On average the drafters underestimated carcass weight by 4.0kg.

Effect of high and sustained zinc supplements on trace element metabolism in sheep - Lee J; Grace ND; Martell S (Proceedings of the New Zealand Society of Animal Production, 1991)
Alpha-lactalbumin (alpha-lac) is a component of the enzyme complex lactose synthetase which plays a key role in the regulation of lactose synthesis and milk water secretion. Ribozyme mediated manipulation of alpha-lac expression should enable more precise elucidation of its physiological significance and may lead to the development of transgenic animals. Five ribozymes and controls targeting different regions of the alpha-sac gene have been synthesised and cloned. In vitro ribozyme analysis involved the incubation of in vitro transcribed alpha- lac and ribozyme RNA. The rate of ribozyme cleavage in vitro was influenced by temperature, MgC1 2 concentration, length of antisense flanking sequences and region of the alpha-lac gene targeted. In vivo ribozyme analysis was carried out in the T7/vaccinia expression system using C127I mouse mammary cells. This system utilises the powerful bacteriophage T7 RNA polymerase which is expressed when cells are infected with a recombinant vaccina virus. Gene constructs, cloned into vaccina plasmids downstream from a T7 promoter are transfected into the cells and are transcribed and translated at very high levels. Using this system we have identified that ribozymes that targeted exposed stem loops and the 3' end of the gene down regulated the level of alpha-lac RNA to 10-20% of the controls. Similar reductions in expression of alpha-lac protein were observed for these key ribozymes, but in addition a full length antisense was equally as effective. The expression of these ribozymes in transgenic mice will enable evaluation of their effectiveness to influence lactose synthesis and milk water secretion.