A physiological basis of genetic improvement in milk production of Friesian and Jersey cows - Davis SR; Hughson GA; Bryant AM; MacKenzie DDS (Proceedings of the New Zealand Society of Animal Production, 1985)
Changes in rumen digesta and electrolyte composition were investigated in 4 high (HS) and 4 low (LS) bloat susceptible cows for 7.5 h following intraruminal loading with 10 litres water containing 0 (L), 1.76 (C), 3.52 (H) or 7.04 (HH) moles Na. Pre-treatment Na concentrations averaged 130 mmol/litre for both susceptibility groups, with increases averaging -20, 10,42 and 95 mmol/litre after addition of L, C, H and HH respectively. Susceptibility groups did not differ in rate of return of Na concentration toward pre-treatment values. Increasing Na loading decreased fluid loss from the rumen but LS cows consistently lost more fluid than HS cows, with no treatment- susceptibility interaction.

Prediction of lamb carcass composition from GR and carcass weight - Kirton AH; Duganzich DM; Feist CL; Bennett GL; Woods EG (Proceedings of the New Zealand Society of Animal Production, 1985)
A lean-growth index (LGI) incorporating growth rate and the proportion of that growth which is fat is calculated by first converting live-weight differences into differences in weight of lean tissue and then adjusting these values using an estimated breeding value for fat depth. The adjustment of fat depths for weight is by within-flock double-log regression or by specifying a constant exponent in the relationship between fat depth C and live weight. Simulation studies suggested that the constant-exponent method was superior for smaller groups of sheep. Improvements in LGI by selection appear more likely to arise from genetic increases in growth rate than from decreases in weight-corrected fatness, but the inclusion of fatness in the index should lead to the production of lambs that can be taken to heavier weights before becoming overfat.

A preliminary investigation into factors affecting lamb growth on Taranaki hill country - Thomson NA; Brown WB; Mace MJ (Proceedings of the New Zealand Society of Animal Production, 1985)
Lactating or non-lactating Coopworth ewe hoggets were offered low, medium or high herbage allowances for 8 weeks during lactation in each of 2 years. Herbage allowance had only a small effect on the penalty of a hogget lactation. Relative to their non-lactating counterparts, the hoggets that had lactated were on average 12.8 kg lighter at weaning and had a 0.29 kg lower clean fleece weight. These penalties are larger than those reported in other New Zealand studies in which the lactating hoggets were preferentially fed. The lambs reared by the hoggets had live-weight gains typical of those observed in twin lambs reared by adult ewes.

The presence of kallikrein-like enzymes in bovine saliva - McIntosh JT; McLaren RD; Carr DH; Howe GW; Cockrem FRM (Proceedings of the New Zealand Society of Animal Production, 1985)
Normal calvings among 527 cows in a Ruakura Research Station herd (No.1) were not evenly distributed throughout the 24 hours. They were most frequent in the early morning (0100 h to 0600 h, 39%) and afternoon (1300 h to 1900 h, 29%). This diurnal pattern was consistent between years. Altering feeding time from 0700 h to either 1600 h or 1900 h did not increase the frequency of daylight calvings. Feeding at 1900 h did produce 2 periods of intensive grazing each 24 h instead of only one. If a beneficial change in calving pattern is to be produced, it may be necessary to disrupt the period when most cows rest (0100 h to 0600 h) by feeding at around 0300 h.

Replacement policies for dairy cows - McArthur ATG (Proceedings of the New Zealand Society of Animal Production, 1985)
In anoestrous ewes that have been primed with progestagens, the introduction of oestrous ewes together with the teaser rams at progestagen withdrawal increased the percentage of ewes exhibiting oestrus over the subsequent 7 days (19.% teaser rams only v 24.4% teaser rams + oestrous ewes; Experiment 1) and the percentage of ewes ovulating in the subsequent 5 days (7.7% teaser rams only v 21.6% teaser rams + oestrous ewes; Experiment 2). The introduction of oestrous ewes without teaser rams in Experiment 2 failed to stimulate anoestrous ewes to ovulate. When rams were placed with oestrous ewes for 2 days before they alone were introduced to anoestrous ewes, the percentage of ewes ovulating was similar to when rams plus oestrous ewes were present together (38.1% stimulated teaser rams v 35.0% teaser rams + oestrous ewes; Experiment 3). Both of these treatments resulted in more ewes ovulating than in the isolated ewes (0.0%) with the response to unstimulated teaser rams (19.5%) and to oestrous ewes alone (9.5% being intermediate.

Resistance and susceptibility to fleece yellowing and relationships with scoured colour - Wilkinson BR; Aitken FJ (Proceedings of the New Zealand Society of Animal Production, 1985)
Data from 1048 young Angora goats by 15 sires in the Department of Lands and Survey's flock at Waitangi were used to obtain preliminary estimates of the effects of year, age of dam, sex, rearing rank and birth day (age). Characters studied included weaning weight, 6- and 12- month fleece weight, and yearling fleece weight (the sum of 6- and 12- month weights). Estimates were also obtained of the heritabilities of, and the genetic and phenotypic correlations among, these traits. The weaning weights of kids out of dams aged 3, 4, 5 and 6+ years of age were heavier (P<0.001) than those out of 2-year-old dams by 1.9, 2.2, 2.0 and 2.5 kg respectively. Corresponding differences for 6-month fleece weight of kids were 0.05, 0.05, 0.04 and 0.04 kg (P<0.01) but those for 12-month fleece weight were not significant. Males were heavier at weaning than females (1.6 kg, P<0.001) and also had heavier 6-, 12-month and yearling fleece weights (0.08, 0.10 and 0.18 kg respectively; P<0.001). Single-reared animals had significantly heavier weaning weights and 6-month and yearling fleece weights than multiple- reared animals (2.4, 0.09 and 0.11 kg, respectively). Age was a highly significant source of variation for all traits. The heritabilities of weaning weight, and 6-, 12-month and yearling fleece weights were respectively 0.28, 0.23, 0.40 and 0.53. Genetic correlations between weaning weight and 6-, 12-month and yearling fleece weights were respectively 0.0, 0.38 and 0.24. Corresponding phenotypic correlations were 0.58, 0.28 and 0.44.

Response of cows differing in bloat susceptibility to intraruminal water and electrolyte loading - Carruthers VR (Proceedings of the New Zealand Society of Animal Production, 1985)
A simulation model of dairy herds was built to examine the economic consequences of alternative culling policies. Only culling cows on the basis of their first lactation was examined because previous studies had show that it is not worthwhile acquiring more information before making the culling decision. The simulation model shows that the culling decision is sensitive to the ratio of cull salvage value to replacement cost. At a ratio of 0.7, a third of first lactation cows should be culled. Used optimally to make replacement decisions, herd testing is worthwhile particularly if the less expensive alternate month test is used.

A review of the importance of wool traits as genetic improvement objectives and selection criteria for New Zealand Romney sheep - Wickham GA; McPherson AW (Proceedings of the New Zealand Society of Animal Production, 1985)
Genetic parameters of loose wool bulk were estimated by half- sib correlations for Romney ewe and ram hogget fleeces sampled at Tokanui Research Station, Romney and Perendale ewe hogget fleeces sampled at Rotomahana Research Station and Perendale ewe hogget fleeces sampled from 5 industry flocks. Daughter-dam analyses were used to estimate similar parameters for Perendale ewe fleeces sampled at Whatawhata Hill Country Research Station. Heritability estimates for loose wool bulk were 0.34

Skeletal changes and some muscle-skeletal relationships during growth and undernutrition in sheep - Young MJ; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1985)
Eight Friesian bull calves from high breeding index (HBI) parents (mean BI=134) and 8 from low breeding index (LBI) parents (mean BI=104) were allocated to 1 of 2 levels of milk intake from 3 weeks of age until weaning at 7.5 weeks of age. The calves were then grazed at pasture and weighed at 21 to 25 weeks of age. LM calves consumed more herbage organic matter (OM) both before (P<0.01) and for 3 weeks after (P<0.05) weaning. Increasing daily milk intake by 1 litre decreased daily herbage OM intake by 0.11 kg. The total DE intake from 3 weeks to 10.5 weeks of age did not differ significantly between treatments. HM calves grew faster (P<0.05) than LM calves in the pre-weaning period, but no differences were observed from them on. At no stage were significant differences observed in calf live weights between milk treatment groups. There were significant differences in growth rate or herbage intake between BI groups, nor any significant interactions between BI and levels of milk intake.

Suppression of T-cell function in the pregnant ewe - Griffin JFT; Davis GH (Proceedings of the New Zealand Society of Animal Production, 1985)
Increased payment to farmers for leaner lamb carcasses places greater emphasis on specifying target carcass weights and grades on individual farms. In the past there has been little objective information available to help the farmer set these targets and make livestock buying and selling decisions. At the Tomoana freezing works in Hawkes Bay new computer outputs have been introduced to provide the farmer with better information for farm management decision-making. A more detailed lamb grading analysis presenting the number of carcasses within each grade at each carcass weight, and a new output named a "fat trend report" are provided. The fat trend report estimates the relationship between the GR fat depth and carcass weight for each mob of lambs slaughtered. Combined with an iso-dollar overlay, the fat trend report assists in establishing production targets in future mobs for each sheep breed and sex farmed. It is suggested that financial incentives for leaner lamb carcasses should be further increased, to bring carcasses closer to the New Zealand Meat Producers Board's ideal.

Swimming speed and fertilisation rates of ram sperm from high and low prolificacy populations - Moore RW; Wilson MC; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1985)
The composition of 2 groups, comprising 70 and 837 lamb carcasses, was predicted from hot carcass weight (HCW) and GR separately and together, these being the main observations considered in the export lamb carcass grading system. GR was a better predictor of composition than HCW with the 2 in combination tending in most cases to be slightly better than GR alone. These measurements could account for 50 to over 70% of the variation in carcass fat and bone and 26 to 47% of the variation in carcass muscle. On average, for each 1 mm decrease in GR, carcass fatness decreased by about 1 percentage unit, muscle increased by about 0.5 percentage units and carcass bone increased by just under 0.5 percentage units.

The association between selenium status and milk production in dairy cattle - Ryan TJ; Sproule RA; Fraser AJ; Anderson DC; Clark RG; Pederson EO (Proceedings of the New Zealand Society of Animal Production, 1984)
Ewe hoggets were run at 2 stocking rates and at 4 levels of injection with hydroxycobalamin (0, 30, 100 and 3,000

The breath-test for sheep: a possible means of identifying lean genotypes - Peterson SW (Proceedings of the New Zealand Society of Animal Production, 1984)
The effect of Ralgro on growth and carcass composition was examined in 3 lamb trials, in young and 15-month old bulls and in spayed and entire heifers. There was no consistent growth response to Ralgro in any of the trials, except for the spayed heifers. Increased meat percentage from Ralgro was found only in young bulls. Aggressive bull behaviour was controlled by Ralgro only in young bulls from April-July at approximately 8 to 11 months of age.

Consumer acceptance of ram and wether meat in the U.S.A. - Field RA (Proceedings of the New Zealand Society of Animal Production, 1984)
Industry Coopworths, industry Perendales and closed lines of Romneys intensely selected for (HFR) or against (LFR) twinning, were raised in individual farmlets with ewe stocking rates of 26 (H), 21 (M) and 16 (L) ewes/ha. Lambs were slaughtered at 16, 20 and 24 weeks of age. The correlated response to selection for twinning was decreased fat depth at equal ewe stocking rates and birth-rearing status. HFR compared to LFR also increased fat depth less when weight was increased by a reduction in stocking rate. Perendales compared to Coopworths had less fat depth and increased fat depth less, when weight was increased by a reduction in stocking rate. The results suggest that fatter breeds will be comparatively leaner at high stocking rates.

The determination of mineral requirements of sheep and cattle - Grace ND (Proceedings of the New Zealand Society of Animal Production, 1984)
Factors to be considered in implementing a programme for the prevention and treatment of trace element deficiencies in livestock are outlined. These are species, age, dietary requirements, seasonal patterns in the deficiency, the pharmacology of the therapeutic agent, its mode of administration and cost. Specific treatment of cobalt, selenium and copper deficiency is discussed.

The development and application of ELISA detection of Lolium endophyte in ryegrass staggers research - Musgrave DR; Fletcher LR (Proceedings of the New Zealand Society of Animal Production, 1984)
To apportion the intake of metabolisable energy (MEI) used for synthesis of lean and fat tissue, current knowledge of substrate oxidation and substrate utilisation for biosynthetic reactions has been combined with estimates of fat and protein turnover to develop models of energy metabolism and nutrient fluxes in a lean 20 kg male and a fat 40 kg female sheep, each gaining 200 g/d. When the most efficient pathways and lowest turnover rates are employed the biosynthetic reactions account for 38 and 34% of MEI in the lean and fat animals. These values rise to 45 and 43% of MEI respectively when higher estimates of turnover and less efficient pathways are used in the calculations. Hormonal regulations of metabolite utilisation is believed responsible for such differences but hitherto, only glucose-insulin system has been quantitated. Two techniques used for its quantitation are described to provide examples of the methods needed to elucidate the control of nutrient utilisation and ultimately body composition in ruminants.

Diagnosis of mineral deficiencies in sheep and cattle - Clark RG; Towers NR (Proceedings of the New Zealand Society of Animal Production, 1984)
Results from vitamin B12 response trials are used to illustrate a methodology which it is claimed will provide a more useful interpretation of animal tissue analyses for the diagnosis of trace element deficiencies. Traditional reference ranges which divide tissue levels into the categories of responsive, marginal, and adequate are replaced by reference curves which, for a given tissue level, provide the expected response and the probability of an 'economic response. The approach should provide farmers and veterinarians with better information to decide on remedial action. The prospects look promising for the production of reference curves for cobalt and selenium, and hopeful for copper. It is suggested that the methodology could be applied in other biological systems involving deficiencies, in particular, to the diagnosis of phosphorus and other deficiencies in plants.

Diet selection of young ruminants in late spring - Hughes TP; Sykes AR; Poppi DP (Proceedings of the New Zealand Society of Animal Production, 1984)
Earlier trials indicated that pasture quality (% green DM in the sward) and pasture accessibility (green DM/ha) can be more limiting to ewe live-weight gain prior to mating than pasture allowance. Two trials investigated the effects of summer grazing management on subsequent pasture quality. From weaning to the start of flushing ewes were grazed lax (residual >2000 kg DM/ha) or hard (residual <1500 kg DM/ha). A live-weight difference of 4 kg occurred at the start of flushing and reduced to 2.5 kg at mating. Main effect results showed that at similar green allowances, ewes flushed on pasture which had previously been hard grazed had live-weight gains 20 to 30 g/d more than ewes on lax grazed pasture. There were no differences in ovulation rate but he live-weight results suggest that there would on average be an advantage to flushing on hard grazed pasture. Wool production was affected similarly to live weight. Management implications are discussed.

Dressing percentages of lambs - Kirton AH; Carter AH; Clarke JN; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1984)
Overseas comparisons have indicated sheep breeds and strains with improved growth rates and lean meat production to those currently available in New Zealand. Most studies in U.K. and Eire have generally shown fastest growth and lean tissue gain amongst offspring by the large down breeds, the Suffolk and Oxford. These results are generally comparable with New Zealand studies. In addition, there has been considerable European interest shown in the Texel for its high yield of lean relative to fat and bone, including lean yield in high value areas of the carcass. The white fleece and moderate fecundity of this breed also favour its maternal use to improve flexibility of lean lamb production. In most studies in the U.S. crossbred lambs sired by Suffolk rams fastest to reach slaughter weights before other meat breeds. This breed is of widespread popularity for lamb production in the U.S. Indirect comparisons suggest a greater growth superiority (5%) of crossbred lambs sired by U.S. Suffolks overseas compared with those sired by New Zealand Suffolks in this country.

Effect of herbage allowance on the performance of pregnant beef heifers - Nicoll GB; Smeaton DC; McGuire KR (Proceedings of the New Zealand Society of Animal Production, 1984)
Investigations into perennial ryegrass staggers, a neurotoxic disease affecting sheep, cattle, horses and deer in New Zealand, recently incriminated a fungus growing as a endophyte in perennial ryegrass in the occurrence of this disease. This Lolium endophyte (an Acremonium sp.) is most prevalent in the lower parts of infected ryegrass plants (leaf sheath) but invades the inflorescence and seed. Newly-emerging ryegrass seedlings are so infected. The close association of the endophyte with the present of lolitrems, potent neurotoxic tremorgens previously isolated from staggers-producing pasture samples, further incriminated the endophyte in the occurrence of ryegrass staggers. Subsequent lamb grazing trials on plots sown with lines of either high- or low-endophyte ryegrass seed confirmed that adequate intakes of short- grazed ryegrass material readily produced ryegrass staggers in all lambs grazing the endophyte-infected plots but there was little or no disease on low-endophyte plots identically grazed. The trials also revealed that the spring-sown high-endophyte ryegrass plots had considerable drought resistance and persistence when compared with low-endophyte plots. The infected swards were found to be highly resistant to Argentine stem weevil attack and a significant insect- feeding deterrent factor has since been detected in endophyte-infected ryegrass. A subsequent sheep grazing trial was indicated that plots sown in autumn with fungicide-treated seed to control endophyte and then conservatively grazed in the first year subsequently gave good production and also provided excellent protection from ryegrass staggers.

The effect of melatonin on the onset of first oestrus in Romney ewe lambs - Moore RW; Miller CM; Lynch PR; Welch RAS; Barnes DR; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1984)
There is increasing evidence that a non-steroidal compound, inhibin, produced by the ovary is involved in the regulation of follicle stimulating hormone (FSH) production by the pituitary. Our studies have shown that ovarian inhibin is present in follicular fluid, that it is synthesised exclusively by follicular granulosa cells, that androgens regulate its synthesis and that it is predominantly a product of healthy follicles, i.e. follicles with the potential to attain ovulatory granulosa cell inhibin production which then suppresses pituitary FSH secretion thereby limiting the number of follicles that can be stimulated to develop to ovulatory maturity. Ovulation rates of Romney ewes actively immunised with a semi-purified preparation of inhibin derived from bovine follicular fluid were significantly higher than those of control ewes (2.06

Effect of 'Ralgro' on growth, body composition and behaviour of lambs, heifers and bulls - Bass JJ; Jagusch KT; Jones KR; Reardon TF; Day AM (Proceedings of the New Zealand Society of Animal Production, 1984)
In 5 trials involving lambs grazing either lotus (L) or white clover (WC) in summer/autumn, those on L were consistently less fat. In trial 1 Romney wether lambs (n=12), grazed 62 days, had weight-corrected carcass fat depths C of 2.1 (L) and 3.4 (WC) mm. In trial 2 Romney hoggets (n+10) grazed 40 days, L had a lower side fat percent than WC at a similar weight. Trial 3 compared Romney lambs (n=20) of the same weight. After 80 days fat depths were significantly lower for L. In Trial 4 Southdown x Romney lambs (n=24), grazed for 45 days. Several measures of fatness were significantly lower in the L group after correcting for initial fatness and carcass weight. Trial 5 was similar to trial 4 (n=16), but continued over 76 days and the differences in fatness were greater. Growth rates of the lambs in these trials were in favour of the WC group by an average of about 15 percent. The lotus tannin content was 10 to 30 g/kg DM. It is concluded that lambs grazed on pure lotus are likely to be less fat than lambs of the same weight grazed on clover, possibly because the protein of lotus is to some extent protected from rumen degradation by tannins, thus effectively increasing its protein content.

Effect of season on ovarian and pituitary activity in cows - McNatty KP; Heath D; Lun S; Henderson KM; Hudson N; Gibb M; McDiarmid J; Montgomery GW; Thurley DC (Proceedings of the New Zealand Society of Animal Production, 1984)
One hundred and four ewe lambs born in 1980 to either ewes that had been immunised against steroid hormones or untreated control ewes were retained for study of their subsequent growth and reproductive performance. There was no significant effect of dam immunisation on growth rate or reproductive performance as hoggets, 2-tooths or 4- tooths. Dam breed (Coopworth or Romney) was the major factor influencing reproductive performance. Mean lamb birth weight was 3.7 kg, weaning weight 18.7 kg, hogget mating weight 40.0 kg, 2-tooth mating weight 54.4 kg and 4-tooth mating weight 60.4 kg. At 9 months of age 83% had exhibited oestrus and their ovulation rate was 1.08, as 2- tooths, 96% mated in the first cycle with an ovulation rate of 1.68 and a conception rate of 80% to first service. They had a lamb drop of 1.49 lambs born/ewe joined and weaned 1.35 lambs/ewe joined. The respective figures as 4-tooths were 98%, 1.8, 85%, 1.43 and 1.34. These data indicate that immunisation of ewes against steroid hormones has no adverse effects on the performance of their progeny.

Effect of shearing on meat and wool production from lambs reared on hill country - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1984)
The effect of winter and early spring feeding levels, lambing status and ewe age on staple strength, fibre diameter at the point of break, and position of staple break were measured in pregnant Romney and Coopworth mixed-age ewes at Whatawhata and Ruakura, respectively. Mid-pregnancy feeding levels produced significant differences in staple strength (37 v 20 newtons/kilotex in the Romney; and 52 v 45 N/ktex in the Coopworth) and diameter at the point of break (37 v 34

The effect of stocking rate on response to cobalt supplementation in sheep - McQueen IPM (Proceedings of the New Zealand Society of Animal Production, 1984)
Six young red deer stags were placed on a photoperiod of 5 alternating periods of 2 months of 16 hours light: 8 hours dark each day (16 L:8 D) followed by 2 months of 8 L:16 D for 20 months. Food intake, whether the antlers were present, and if present, whether growing, cleaning or hard and testis diameter were recorded. Each stag showed 5 peaks and 5 troughs of food intake in response to the manipulated photoperiod. There were 4 cycles of gonadal development and regression as the testes did not descend from the inguinal canal during Period 1; testes grew in short day periods and diminished in size in long day periods. There were 4 cycles of antler growth and casting; antler cleaning occurred on short days and casting on long days. Male red deer are capable of responding to a square wave daylength pattern as a sinusoidal pattern.

The effects of lamb breed, slaughter age and sex on carcass fat depth and export grade - Geenty KG; Young SR; Clarke JN; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 1984)
A least squares analysis of the weight of 15 individual export cuts from 808 carcasses of 20-month old steers identified significant effects of carcass weight, carcass fat measurements, carcass grade and sire breed on the weight of export cuts. Increasing carcass weight had a positive effect on cut weight but increasing carcass fatness had a variable effect on weight of cut. The weight of cut marketed with negligible subcutaneous fat (cube roll) decreased in weight by 7% as carcass fat depth increase from 4 to 12 mm. In contrast a cut which included subcutaneous fat increased in weight by 15% over the same fatness range. The data show that the most equitable pricing system (schedule) would take account of weight of individual cuts.

Embryonic and genetic engineer - Brief Communication - Baker RL (Proceedings of the New Zealand Society of Animal Production, 1984)
The evidence on the influence of herbage allowance and sward characteristics upon animal performance and herbage production is reviewed briefly, with particular reference to the prediction of animal performance, the use of decision rules in grazing systems and understanding of animal/sward interrelationships. Attention is concentrated on evidence from temperature grasslands, with particular reference to New Zealand results. Simple management rules based on herbage allowance or residual dry matter indices have made a major contribution to improvement in the efficiency of grazing management. However, their use as general indices is restricted by the interdependence of the effects of variation in allowance and sward conditions upon animal performance. Furthermore allowance-based studies make only a limited contribution to understanding of the factors influencing the links between the plant and animal components of grazing systems. It is suggested that more attention should now be concentrated on the causative effects of variation in sward characteristics upon both herbage production and animal performance

Expected selection responses in lamb carcass composition and weight - Bennett GL; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1984)
Twenty eight Border Leicester 2-tooth rams (mean live weight 70 kg) were scored for fatness on a 10-point scale by 6 drafters and back fat thickness was measured by ultrasonic probe (UFD). Chemical fat percentage (mean 33.9%) was determined on a half-carcass of each ram. Mean carcass weight, measurement C and GR were 38.0 kg, 12 mm and 28 mm respectively. Mean drafters' fat score was more highly correlated with % carcass fat (+0.83) than UFD (+0.67). The prediction of fat-free carcass weight (FFCW) from live weight plus UFD (R2=0.72, RDS 1.24 kg) or drafters' fat score (R2=0.76, RSD 1.14 kg) was superior to prediction from live weight alone (R@=0.59, RSD 1.49 kg). The inclusion of UFD o9r drafters' fat score increased the efficiency with which rams were ranked for fat-free carcass weight. Selection of the top 10% of rams ranked on the prediction of FFCW from live weight achieved 75% of the potential selection differential. Inclusion of either UFD or drafters' score improved the potential to 95%.

Fatness of lambs grazed on 'Grasslands Maku' lotus and 'Grasslands Huia' white clover - Purchas RW; Keogh RG (Proceedings of the New Zealand Society of Animal Production, 1984)
Crossbred lambs involving specialist meat breed (Expt. A) or long-woolled breeds (Expt. B) were slaughtered at ages ranging from 12 to 30 weeks. Carcasses were classified retrospectively into current export grades according to their weight and fat measurement GR. In both experiments measurement GR was related to carcass weight (r=0.57 to 0.83) and increased, on average, by just over 1 mm per kg carcass weight increase. Proportions of carcasses grading 'trimmer' or 'overfat' increased at carcass weights above 15 kg or at slaughter ages greater than 18 weeks. In Expt. A, 4% of carcasses graded 'overfat' at the 12 week slaughter age and 81% at 30 weeks. There was little difference in the grade distribution of carcasses among sire breeds in Expt. A (Southdown, Suffolk and Dorset Down) but in Expt. B lambs reared by Corriedale ewes showed higher proportions of 'trimmer' (25%) and 'overfat' (18%) carcasses compared with those reared by Romneys (10% and 2% respectively). It is suggested that the higher carcass fat of lambs from Corriedale ewes is due partly to greater milk consumption compared with those suckled by Romneys.

Fleece tenderness: the effect of nutrition, age and lambing status on pregnant Romney and Coopworth mixed-age ewes - Fitzgerald JM; Smeaton DC; Jagusch KT (Proceedings of the New Zealand Society of Animal Production, 1984)
The potentially high levels of productivity of fitch - 2 litters per year, 8 young per litter - is rarely achieved in practice. Annual litter rates vary from 0.9 to 1.7 per female kept, due to high rates of false pregnancy (up to 90%). Kit mortality can reach high levels (to 50%). Young fitch grow rapidly and reach mature body size at 20 weeks (males 1400 g; females 800g). Subsequent fluctuations in body weight are attributable to adipose depositions.

Grazing behaviour of sheep and ryegrass staggers - Keogh RG (Proceedings of the New Zealand Society of Animal Production, 1984)
Two experiments investigated relationships between biochemical measurements and carcass fat in lambs. In the first, artificially reared Dorset lambs, weaned at 5 (early) or 13 (late) weeks were slaughtered at 5, 9 and 13 weeks for carcass fat determination. In the second experiment, 330 Coopworth male lambs (entire and castrate), were weaned at 9 weeks of age and slaughtered at 21 weeks. At 9 and 13 weeks of age early weaned lambs which had lower carcass weights had significantly lower glucose and insulin levels, and less internal and carcass fat than milk fed lambs. In the second experiment a similar carcass weights entire lambs were leaner than castrates and had lower blood glucose. In contrast to results in the first experiment, lambs grown to slaughter under a uniform dietary regime in the second showed a negative correlation between insulin and fat measurements. It is suggested that insulin is an important regulator of fat deposition in the milk fed lamb but its exact role in the ruminant lamb remains unclear.

Herbage allowance, pasture quality and milkfat production as affected by stocking rate and conservation policy - Thomson NA; Lagan JF; McCallum DA (Proceedings of the New Zealand Society of Animal Production, 1984)
Four cows were fitted with unilateral temporary cannulae to both parotid and mandibular glands in an experiment designed to determine which salivary proteins were secreted by these glands. Parasympathomimetic stimulation produced a large salivary flow from the parotid gland (50.8 ml/min) with a relatively low protein concentration. Mandibular flow rates were lower, but the protein concentration was high giving a total protein of 1.3 mg/min. Sympathomimetic stimulation, during a parasympathomimetic booster, reduced the flow rates from both glands but increased the total protein output 7-fold from the parotid and 8-fold from the mandibular gland. Band 4 was the major protein secreted by the parotid gland while bands 3, 7 and 8 were the major bands secreted by the mandibular gland.

Influence of age of early weaned lambs on intake, digestibility and retention time of clover hay - Cruickshank GJ; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1984)
A simulation model was used to generate functions to evaluate winter and spring feed priorities for replacement hoggets and ewes on North Island hill country. The functions relate ewe, hogget and lamb live weights at the end of the respective seasons to seasonal stocking rate and live weight and pasture cover at the start of the season. The site simulated was Ballantrae Hill Country Research Station. At high stocking rates, switching priorities from hoggets in winter (relative stocking rate, 1 hogget/ewe) to ewes in spring (2.4 hoggets/ewe) provided no benefit to ewe and hogget live weight at weaning, compared to other selected winter/spring strategies (eg. 1.2/2.05 or 1.4/1.8 hoggets/ewe). However, lamb weaning weight was greater under the former strategy. The same pattern held for lower stocking rates. Imposition of system constraints reduced the apparent advantages displayed in the general functions. Rationing feed to hoggets in spring was important to success at high hogget stocking rates.

Influence of green leaf distribution on diet selection by sheep and the implications for animal performance - L'Huillier PJ; Poppi DP; Fraser TJ (Proceedings of the New Zealand Society of Animal Production, 1984)
Twelve lambs, weaned at 6 weeks of age, were used to study the development of rumen function from 6 to 24 weeks of age when offered clover hay ad libitum. Six of the lambs were cannulated at the abomasum on weaning and the remaining 6 remained intact. Dry matter intake (g/kg live weight) increased rapidly until 10 weeks of age and subsequently remained constant at 33 to 37 g DM/kgLW. in vivo DM digestibility and marker rumen retention time decreased initially (0.693 in week 7 v 0.664 in week 9 and 14.5 hours in week 8 v 10.9 hours in week 12 respectively) but were constant thereafter. The proportion of digestible DM apparently digested in the rumen was low (0.45) but was similar at 8, 12 and 16 weeks of age. There were no differences between the intact and cannulated lambs in DM intake and digestibility or in marker retention time in the rumen.

Influence of individual beef cuts on net carcass value - Selbie PB; Nicol AM; Mellon MJ; Bass JJ; Duganzich D (Proceedings of the New Zealand Society of Animal Production, 1984)
Expected rates of genetic change in lamb growth and composition were calculated for 2 different selection goals; increase in lean growth rate (LRG) and decrease in weight-adjusted % fat (APF). Carcass fatness was measured in a number of ways on an animal's own or its relatives' performance. Under either selection goal, all selection programmes resulted in reduced % fat adjusted for age. All selection programmes for either selection goal improved lean weight but there was little improvement over selection for live weight alone. Alternatively, use of fat measurements did not decrease lean weight improvement and resulted in leaner carcasses. Changing carcasses from 13.5 kg and 25% fat to at least 15 kg and no more than 24% fat was most quickly achieved by selecting against APF.

The influence of pasture allowance on performance of autumn- shorn lambs - Pownall DB; Lucas RJ; Abrahamson M (Proceedings of the New Zealand Society of Animal Production, 1984)
Seasonal wool growth and staple strength were measured in mature, non-pregnant Romney ewes individually penned indoors or confined as a group in a yard outdoors and offered a maintenance ration of lucerne chaff. Clean wool growth was lowest during winter (4.6 and 5.0 g/d for indoor and outdoor ewes, respectively) and greatest during summer for indoor (11.3 g/d) or spring for outdoor (11.9 g/d) ewes. Efficiency of wool growth (g wool growth/d per kg dry matter intake/d) for indoor sheep was 5.6, 8.8, 11.8 and 7.8 during winter, spring, summer and autumn, respectively. There were positive relationships between mean wool growth, staple strength and efficiency.

The insemination of sheep with fresh or frozen semen - Tervit HR; Goold PG; James RW; Fraser MD (Proceedings of the New Zealand Society of Animal Production, 1984)
The preovulatory follicle in oestrous cycling Angus cow was larger (P<0.01) and contained more granulosa cells (P<0.01) in May and June than in October. Also in May and June, the corpora lutea were heavier (P<0.05) and secreted more progesterone (P<0.01) than in October. In contrast, the luteinizing hormone peak frequency and plasma prolactin concentrations were higher (P<0.01) in October than in May and June. Seasonal differences in ovarian activity are probably a direct consequence of seasonal differences in pituitary gonadotrophin secretion.

Integrating management of sheep and deer - Brief Communication - Harbord MW (Proceedings of the New Zealand Society of Animal Production, 1984)
A trial at Tokanui and Templeton Research Stations was designed to compare the Charolais and Murray Grey breeds as terminal sires. There were calvings at both stations in 1980, and at Tokanui in 1981. Ten Murray Grey and 7 Charolaise sires were used over crossbred cows to calve at 3 years or older in 1980, with the same cows in 1981, generating respectively 231 and 223 calves/breed. Sires were used in common across years and stations by artificial insemination, and reference sires were used to link earlier Charolais data. Of calves born, 1.7% sired by Murray Greys and 7.2% sired by Charolaise bulls had birth difficulties; in total 3.5% and 7.6% of calves respectively died before weaning. Relative to Murray Grey-sired calves, birth weights of Charolaise-sired calves were 8 kg (24%) higher; weaning weights at 4 to 5 months of age were 22 kg (13%) higher, with a similar percentage margin at 12 and 16 months. Weight of calf weaned per cow calving was 6% higher for Charolais-sired calves, making due allowance for different calf death losses and gestation lengths.

Lamb live weights at slaughter and carcass grades - Bray AR (Proceedings of the New Zealand Society of Animal Production, 1984)
Dressing percentage (DO%), the dressed carcass expressed as a portion of live weight, is markedly influenced by the particular definition used. Farmers usually want to estimate cold (works) carcass weights (CCW) from live weights taken on lambs recently removed from pasture (FLW). Gut fill plays a major role in DO%. As lambs empty out after removal from pasture, DO% increases until this effect is offset by loss of carcass and organ weights from increasing periods of starvation. Data on 2207 weaned and shorn lambs ranging from 10 to 46 kg FLW and slaughtered over 3 seasons could be described by the regression: CCW (kg) = 0.473 FLW (kg) - 1.92, RSD = 0.67 kg, r=0.95. DO% calculated from this regression for lambs slaughtered close to the New Zealand mean CCW of 13 kg averaged 41% and increased as FLW increased. Shorn lambs of similar weight sired by longwool breeds had lower DO% than lambs sired by Down breeds. Lamb DO% dropped following weaning. Lambs with carcasses in the leaner A and Y grades dressed lower than lambs in the fatter pre 1983-84 P grade when compared at the same live weight, illustrating that DO% increases as lambs get fatter.

Live-weight gains of lambs on limed and unlimed pasture at similar levels of nutrition - O'Connor MB; Jagusch KT; MacLean KS; Edmeades DC (Proceedings of the New Zealand Society of Animal Production, 1984)
No abstract supplied

Management and breeding policies for the use of the Booroola F gene for increased flock prolificacy - Metherell JA (Proceedings of the New Zealand Society of Animal Production, 1984)
Three hundred Romney, Coopworth and Perendale wether lambs reared at the Whatawhata Hill Country Research Station were shorn in either December and April, February and April or only in April before slaughter in May and either well or poorly fed between December and May. Shearing did not affect carcass weight. GR fat depth or export fatness grade. Lambs shorn in December grew most clean wool. Well-fed lambs had a heavier, fatter carcass with more graded P. There was no interaction between shearing treatment and level of feeding. The trial was repeated on 11 commercial hill country farms in the northern half of the North Island using 150 lambs/farm. On 1 farm, where average growth rate exceeded 200 g/d, there was a positive effect on carcass weight from shearing lambs twice before slaughter. On all other farms (growth rates less than 150 g/d) there was no effect (9 farms) or a negative effect (1 farm) on carcass weight from shearing lambs at weaning. Export fatness grade was unaffected by shearing treatment. Wool production was unaffected by shearing treatment for 6 farms, greatest for 2 farms when shorn in December and April and greatest for 1 farm when shorn in February and April. Total net returns from meat and wool for the farm with the fastest growth rate were unaffected by shearing treatment. Total net returns for all other farms were greatest for the group shorn once prior to slaughter. Seventy four wether lambs and 105 ewe lambs were shorn either 3 weeks, 24 hours, or left unshorn before slaughter. Shearing treatment did not affect carcass weight, GR fat depth, export fatness grade or muscle pH.

Methods of ranking two-tooth rams for fat-free carcass growth rate - Nicol AM; Parratt AC (Proceedings of the New Zealand Society of Animal Production, 1984)
Eight herds each of 24 Friesian cows were stocked at 3.7 cows/ha on separate farmlets during 1982-83 and 1983-84. Annual production per5 hectare averaged 710 kg fat, 537 kg protein, 740 kg lactose and 16.7 t solids corrected milk (SCM). Annual DM intake was 15.8 t/ha and live weight (LW) during lactation, 1487 kg/ha. In a contemporary farmlet trial at an adjoining dairy, 4 purebred Jersey herds each of 15 cows were stocked at 2.8, 3.3, 3.8 and 4.3 cows/ha. Regression analysis was used to derive estimates of the performance of the Jerseys at the same stocking rate, and at a stocking rate that resulted in the same LW/ha, as the Friesians. At a common stocking rate of 3.7 cows/ha, the Friesians were estimated to produce 7, 15, and 13% more fat, protein, and SCM/ha than the Jerseys. Annual conversion efficiency (g milk constituent/kg DM) of the Friesians was estimated to be 10% higher for fat and 18% higher for milk solids than the Jerseys. At the same LW/ha, requiring a Jersey stocking rate of 4.21 cows/ha, the Friesians were estimated to outproduce the Jerseys by 3, 13 and 10% for fat, protein and SCM/ha respectively. Annual conversion efficiency for the Friesians was estimated to be 15 and 25% higher for fat and milk solids respectively than for the Jerseys. For Jerseys, estimated maximum yields per hectare of milkfat and milk solids were at 4.45 and 4.37 cows/ha and were 686 kg fat/ha and 1761 kg milk solids/ha; 4 and 13% respectively less than produced by the Friesians stocked at 3.7 cows/ha. The superior production of the Friesians was due to their higher food conversion efficiency, not to the higher food intake.

Mineral nutrients in pasture species - Cornforth IS (Proceedings of the New Zealand Society of Animal Production, 1984)
Where mineral deficiencies have characteristics clinical signs (eg. milk fever or hypocalcaemia) or necropsy findings (eg. white muscle disease) diagnosis is comparatively easy. However, many mineral deficiencies are characterised by poor growth or production which are non-specific signs that can be caused by many factors. In these instances a systematic approach is required to determine if a mineral deficiency is likely to be involved. This paper outlines such an approach which includes: Description of animal health problem including a comparison with target weights and production parameters. Deduction of likely causes using clinical signs, soil, climate, plant and management clues. Diagnosis using appropriate diagnostic tests. The best tests are animal response trials or analysis of animal tissue parameter levels which can be related to a production response. Choice and results of animal diagnostic tests must be considered in relation to what the sampled tissue represents (eg. mineral intake, storage site or where the element functions), and the limitations placed on the test by other factors (eg. effect of concurrent disease). The importance of sufficient sample numbers to reflect herd mineral status and selection of animals for sampling in a random manner is emphasised. Interpretation of results and advice should be based on epidemiological knowledge of the mineral deficiency and the economic benefits of mineral supplementation. The use of animal diagnostic tests to predict some mineral deficiencies (preventive medicine), especially in areas of marginal deficiency, is briefly discussed. Because of the complexity of some mineral deficiency problems a team approach involving farmer, agricultural adviser and veterinarian is recommended.

Ovarian activity in the Booroola x Romney ewe possessing a major gene influencing fecundity - McNatty KP; Henderson KM; Lun S; Heath D; Kieboom L; Hudson N; Fannin J; Ball K; Smith P (Proceedings of the New Zealand Society of Animal Production, 1984)
Prices paid at 6 sales for Perendale fleece wool assessed as having loose wool bulk values of 25 cm

Ovarian inhibin: a hormone with potential to increase ovulation rate in sheep - Henderson KM; Franchimont P; Lecomte-Yerna MJ; Charlet-Renard CH; Hudson N; Ball K; McNatty KP (Proceedings of the New Zealand Society of Animal Production, 1984)
The Booroola F gene gives sheep breeders a unique method of rapidly increasing the prolificacy of their flocks. Research data indicate that on average, every ewe carrying the F gene will produce about 1 extra lamb at each lambing. Breed type need not be changed from those currently favoured as the F gene can be transmitted to any breed, firstly by a series of controlled backcrosses and then by identifying carrier sheep of the desired breed type. Management systems to cope with large increases in lamb drop need to be developed along with breeding programmes to predict more accurately the genotype of individual sheep. These management systems and breeding programmes must also incorporate a strong emphasis on the ability to rear triplet born lambs to a marketable size.

Perennial ryegrass staggers research - an overview - Mortimer PH; Young PW; di Menna ME (Proceedings of the New Zealand Society of Animal Production, 1984)
Defoliation patterns of sheep grazing a staggers-prone, ryegrass-dominant pasture were studied at Palmerston North during the 1982-83 summer-autumn period. The 0.4 ha pasture was grazed for 5 to 8 days each month from November to May by groups of 30 to 50 sheep. Herbage at dung patch sites present in January covered about 25% of the pasture area and remained ungrazed until May. Urine-patch sites covered about 35% (16 to 45%) of the pasture area and although urine- patch herbage was grazed before other types, differences were detected within this category: the most recent urine-patches were defoliated sooner and to a greater extent than older ones. Ryegrass at interexcreta sites was defoliated less frequently and to a lesser extent than that at urine-patch sites, except for those interexcreta sites that also contained white clover. Concentrations of the ryegrass endophyte, Acremonium loliae were higher in live ryegrass sheath at urine-patch than at inter-excreta sites. The results are discussed in relation to the acquisition of neurotoxins by sheep.

Predicting parturition in the ewe from the pattern of uterine motility - Wolff JE; Dobbie PM (Proceedings of the New Zealand Society of Animal Production, 1984)
Shortened daylight hours have been shown to advance the onset of puberty in ewe lambs. In this experiment the pineal hormone melatonin was administered to mimic short days with the aim of advancing the onset of first oestrus in September-born ewe lambs. Treatments were; no melatonin in 10 ml saline drenched daily (control), 2 mg melatonin in 10 ml saline drenched daily and 435 mg of melatonin implanted subcutaneously, each on 2 start dates - February 17 and March 17. Fertile rams were introduced on March 10 and April 7 respectively. All ewes were killed on July 28 and foetal crown-rump lengths measured to estimate the date of conception. The mean dates of first tup in the early treatments were not statistically different (May 25, May 9 and May 13) but there was a difference between the control and implant in the estimated dates of conception (June 1 and May 17, P<0.05). In the late treatment the mean dates of first tup were June 2, May 16 and May 10 respectively (P<0.01). However this difference did not lead to a treatment difference in the estimated date of conception because the percentages conceiving to the first tup were 38, 80 and 21 respectively.

The Prevention and Treatment of Trace Element Deficiencies in Sheep and Cattle - Farquharson BC (Proceedings of the New Zealand Society of Animal Production, 1984)
The association between selenium and milk production was investigated on 98 farms in the Rangitaiki Plains and Galatea Basin during the 1981-82 dairy season. Ten blood samples per herd from randomly selected cows were tested for selenium on 4 occasions through the season. Animal, farm management and trace element supplementation data were also collected. Mean herd selenium levels varied considerably and there was a statistically significant association between herds with low blood selenium and low milk production in terms of kilograms of milkfat per hectare. Selenium milk response trials were carried out in 7 dairy herds in the Rangitaiki Plains district in the 1982-83 dairy season. Half of each herd received injections of selenium each 2 months with the remaining animals acting as controls. In 1 herd additional copper and copper/selenium groups were included. Using Livestock Improvement Association production figures, positive milk volume and milkfat responses were shown to occur on 6 of the farms. On 2 farms volume responses were significant at the 5% level. It was considered that selenium deficiency has a small effect on milk and milkfat production on farms in this district, but that this effect is mediated by other factors.

Price premiums for high-bulk Perendale wools - Elliott KH (Proceedings of the New Zealand Society of Animal Production, 1984)
Weaned lambs are often shorn but the limited research on the practice does not demonstrate a clear advantage. As the level of feeding used in some trails may have led to the variable results, experiments investigated the possibility of an interaction between feeding level and lamb shearing. Pasture allowances of 1 kg and 2 kg DM/lamb/d were offered to shorn and unshorn Romney or Coopworth wether and ewe lambs (19 to 28 kg initial live weight) in 2 autumn trials on rotationally grazed irrigated pasture. In the 105-day 1982 trial the shorn and unshorn lambs were grazed together but in the 55 day 1983 trail they were grazed separately. There was an interaction (P<0.01) in 1983 between feeding level and shearing for carcass weight where shorn lambs offered 1 kg DM pasture allowance produced carcasses which were 0.8 kg lighter than the 10.4 kg carcasses for unshorn lambs fed at the same level. Both shorn and unshorn lambs on 2 kg DM allowance produced 11.7 kg carcases. In 1982 shorn lambs had a 10 g/lamb/d faster live-weight gain and 0.5 kg heavier carcasses than unshorn lambs. Carcass weights were 10.6 kg and 12.8 kg at the 1 kg and 2 kg DM feed allowances. The lack of an interaction in 1982, when shorn and unshorn lambs grazed together, may have been caused by shearing inducing an increased appetite in shorn lambs which resulted in competition for feed with the unshorn lambs. In 1982 rates of live- weight gain were 66 and 102 g/lamb/d and in 1983 40 and 110 g/lamb/d from 1 kg and 2 kg DM allowances respectively. These experiments suggest that while lamb shearing may have some management advantages, carcass weights of shorn lambs may suffer if their growth rates are restricted by limited pasture supplies.

The production characteristics of fitch (Mustella putorius) - Giles KH (Proceedings of the New Zealand Society of Animal Production, 1984)
Results are presented from the first year of a 4-year grazing trial investigating the effects of stocking rate (3.75 and 4.49 cows/ha) and time of conservation, October (early), November (late), on dairy production at the Waimate West Demonstration Farm in South Taranaki. Both stocking rate and time of conservation had a significant (P<0.05) effect on milkfat yield/cow which resulted in large differences between treatments in terms of milkfat production/ha. At the low stocking rate, milkfat production/ha was 645 and 619 kg, and at the high stocking rate 642 and 705 kg for the respective early and late conservation treatments. These differences in animal performance are attributed to differences in pasture allowance in early lactation and to the proportion of dead matter in the pasture over summer and autumn. The proportion of stem in pasture had little direct effect on dairy production but over time it may have contributed to the pool of dead matter causing lower milkfat yields in summer and autumn. The adoption of a high stocking rate and late conservation policy maintained adequate pasture allowance (33 to 35 kg DM/cow/d) in early lactation and a sufficiently intensive grazing pressure in October and November to prepare pastures of low dead and high green content over summer and autumn.

Prospects for the stimulation of lactation and growth of ruminants by the administration of growth hormone and related molecules - Davis SR; Bass JJ (Proceedings of the New Zealand Society of Animal Production, 1984)
Diet selection from 2 swards (ryegrass and prairie grass) vertically stratified into 3 horizons (A, >6cm, B, 3 to 6 cm, C, 0 to 3 cm) was studied using oesophageally fistulated ewes in summer and autumn. Green grass leaf (GGL) contributed 68 to 97% of diets, whilst pseudostem and dead material were rejected. Sward and dietary white clover contents were low in the sward and 0.1 to 4.9% in the diet) and no selection for this component was evident. Defoliation of white clover appeared to be influenced by the vertical distribution of GGL. Green material distribution determined the horizons grazed. Sheep grazed horizon C of summer ryegrass pasture, where 95% of GGL was found. In all other swards the surface canopy (>3 cm above ground level) was composed primarily of GGL (>30%), and sheep grazed this horizon. Low apparent intake (21 g DM/kg live weight/d) was associated with the apparent need to penetrate the surface canopy to obtain GGL in summer ryegrass pasture.

Recent progress and future prospects of the New Zealand Society of Animal Production - Smith JF (Proceedings of the New Zealand Society of Animal Production, 1984)
Ewes were inseminated in 1982 and 1983 at the second oestrus after synchronisation. They received fresh or frozen semen deposited once or twice, either into the cervix, blind in the vagina, onto the ovaries or into the uterine horn lumen. Very poor results occurred after ovarian insemination. More ewes lambed when inseminated with fresh compared to frozen semen, when inseminated twice rather than once, and for 1983, the ranking of insemination positions (best to worst) was intra-uterine, blind, cervix. Ewes lambing after insemination with frozen semen in 1982 produced fewer multiples than those inseminated with fresh semen. A single blind insemination of fresh semen gave a lambing rate (64%) only slightly lower than for cervical deposition (69%) and the intra-uterine technique performed well with both fresh and frozen sperm (83% and 38%, respectively). Both these techniques should be considered for artificial insemination.

Recent trends in conception rates and return patterns in AB herds and their effects on calving patterns - Macmillan KL; Taufa VK; Phillips P (Proceedings of the New Zealand Society of Animal Production, 1984)
The average milkfat test for groups of first Friesian x Jersey (FJ) cows in 9 Waikato herds was 4.68%, ranging from 4.36% to 5.46%. Animals with 75% Friesian breeding had an average test 0.05% lower than their first cross contemporaries whereas those with 25% Friesian breeding had an average test which was 0.25% higher. Variation in colour and height at withers were not reliable indicators of an FJ animal's test. Regression analyses with records of sires' progeny-tested by the New Zealand Dairy Board from 1961 to 1979 showed that each 1 unit increase in milkfat breeding index (BI) in Jerseys was associated with an increase of 0.85 units in milk BI. The comparable figure for Friesians was 0.55 milk BI units. Since 1961, the average milkfat BI of Jersey sires selected for further use has increased by 24 units (117 to 141) with an associated increase in milk BI of 14 units (114 to 128). Comparable changes for Friesian sires were 17 units (121 to 138) and 6 units (115 to 121). The average live weight at calving over 4 seasons at Ruakura for high BI Jerseys was 385 kg compared to 404 kg for 'AB' Friesians. The concurrent increases in milk and milkfat BI's in the Jersey breed may have been associated with a greater increase in live weight than in the Friesian breed. Owners of herds of FJ cows need not expect substantial changes in milkfat test or live weight through the continued use of Friesian sires to produce replacement heifers.

The relationship between New Zealand's geology and soils and trace elements deficiencies in grazing animals - Fraser AJ (Proceedings of the New Zealand Society of Animal Production, 1984)
In determining a mineral requirement an attempt is made to measure the minimum dietary intake of the mineral that is necessary to maintain health and the desired level of production. Two approaches can be used to determine mineral requirements: (a) observation from practical feeding studies where the animal's response is related to the dietary level of the mineral under investigation (b) by calculation using data obtained from mineral balance studies where the losses in the urine, faeces and sweat, together with the amounts absorbed, are measured with other investigations to determine the mineral uptake by body tissues and foetus and the amounts secreted in the milk.

Relationship of subcutaneous fat depth and weight changes induced by stocking rate of 4 lines of lambs - Bennett GL; Clarke JN; Rattray PV; MacLean KS (Proceedings of the New Zealand Society of Animal Production, 1984)
Live weights, carcass weights and GR measurements from 566 Coopworth lambs were used to retrospectively establish criteria that would have directed carcass production away from discounted grades into those receiving premium payments. Greatest financial returns would have been achieved by slaughtering lambs when they approached fatness limits, before penalties applied. When live weights were the only means of selection, returns were greater at weights that resulted in production of some carcasses penalised for fatness and/or heavy weights than at weights that avoided discounted grades.

Relationships between insulin-glucose status and carcass fat in lambs - Munro JM; Geenty KG; Bickerstaffe R (Proceedings of the New Zealand Society of Animal Production, 1984)
Paired 7-rib roasts from heavy ram and wether lambs fed pelleted diets were evaluated by 70 United States lamb consumers. Forty of the 70 lamb consumers preferred rib roasts from wethers. The 40 consumers preferring meat from wethers listed milder flavours along with more tender and juicier meat as reasons for their selection. The 30 consumers who preferred meat from ram lambs did so because the roasts were less greasy and the more intense flavour was preferred. Therefore, differences in intensity of flavour between meat from rams and wethers did exist but lamb consumers were divided on their preference for a stronger or milder flavour.

Relative performance of meat breeds of sheep in New Zealand and overseas - Clarke JN; Bennett GL; Kirton AH (Proceedings of the New Zealand Society of Animal Production, 1984)
A sheep breeding experiment at Woodlands Research Station consists of 5 self-contained Romney selection lines (closed in 1973). Four lines are selected respectively for dam's number of lambs born (dam NLB), 100-day weight, hogget fleece weight, and a production index in which all 3 traits are combined, while the fifth line is a randomly selected control. Back fat thickness was measured in the 1982 born ewe lamb progeny at approximately 8 and 14 months of age. Relative to the controls (back fat 6.3 mm) the dam NLB (5.0 mm) and the production index (4.8) lines had 20% lower back fat depths (P<0.01) in May after variance adjustment for live-weight. The differences were slightly lower when measured in November. The fat thickness of the 100-day weight and hogget fleece weight line progeny were similar to the controls. The heritability of back fat depth adjusted for live weight by half-sib analysis was 0.28

Relative priorities for feed between ewes and ewe hoggets in winter and spring: a modelling analysis - McCall DG (Proceedings of the New Zealand Society of Animal Production, 1984)
Grazing animals obtain most of the mineral nutrients they require from pasture plants. Whilst a knowledge of plant composition alone is of limited value, it is one of a series of clues which can be used to help diagnose or predict animal mineral status. Factors which influence the concentration and availability of minerals in plants are summarised in an attempt to aid the interpretation of plant analyses.

Reproductive performance of ewe offspring from ewes immunised against steroid hormones - Smith JF; MacLean KS; McGowan LT; Potts IR (Proceedings of the New Zealand Society of Animal Production, 1984)
The pattern of ovarian follicular development in Booroola x Romney ewes (6-7 y) with an ovulation-rate >/-3 (F+ ewes) differed from that in Booroola x Romney ewes (6-7 y) with an ovulation-rate <3 (++). The difference was not due to variations in the number of ovarian follicles (>/-1 mm diameter) or in the proportion of healthy follicles which were similar for both genotypes. It arose because follicles in F+ ewes produced oestradiol and reached maturity at a smaller diameter than in ++ ewes. During a prostaglandin induced follicle phase, the secretion rate of oestradiol from ovaries with 3 presumptive preovulatory follicles in F+ ewes was similar to that from ovaries with only 1 such follicle in ++ ewes. Moreover, the total number of granulosa cells (i.e. the oestrogen-secreting cells) in 3 preovulatory follicles from F+ ewes was similar to that in 1 such follicle in ++ ewes. In F+ ewes, the presumptive preovulatory follicles reached 4.6

The research potential of shared information resources - Wickham BW (Proceedings of the New Zealand Society of Animal Production, 1984)
Genetic engineering of micro-organisms to produce mammalian protein hormones promises to make the hormonal treatment of ruminants for the stimulation of lactation, growth and wool growth commercially viable. Treatment of lactating dairy cows with growth hormone (GH) commonly elevates milk production by about 4 kg milk/d. In growing beef and sheep GH increases nitrogen retention, reduces carcass fat content and may increase growth rate. Wool growth increases following the cessation of GH treatment. Many of the actions of growth hormone are likely mediated by a 'family' of hormones, notably insulin-like growth factors I and II and epidermal growth factor. The efficacy of these materials in promoting production has not been investigated. Sustained-release implants have been developed which will deliver protein hormones over prolonged periods. However, the ability to promote production by direct manipulation of the animal genome may be the most economic approach. For example, injection of rat GH genes into fertilised mouse eggs resulted in mice that grew 2 to 4 times faster than normal.

The salivary proteins secreted from cannulated parotid and mandibular glands of cattle after pharmacological stimulation - McIntosh JT; McLaren RD; Howe GW; Cockrem FRM; Carr DH (Proceedings of the New Zealand Society of Animal Production, 1984)
Recent developments in the technology for storing, retrieving and communicating data have lead to the possibility of greatly expanded data sharing. The advantages of extended data sharing in the animal based industries of New Zealand include the possibility of conducting research studies previously considered not feasible because of the resources required to collect and collate the needed data. With the sharing of information between farms, Government agencies, research institutions, servicing organisations and advisory services, it is possible to foresee research studies of considerable benefit to the primary industries in New Zealand. This paper will examine the concept of shared information and provide illustrations from the New Zealand Industry of the research potential.

Seasonal wool production and staple strength of Romney ewes - Geenty KG; Orwin DFG; Woods JL; Young SR; Smith MC (Proceedings of the New Zealand Society of Animal Production, 1984)
The average conception rate (CR) to first insemination in 1969- 70 was 60.6% compared to 67.7% in 1982-83. CR declined with increasing herd size in the latter study (from 70.5% in herds of <101 cows to 66.0% in herds of >300 cows), but this trend was substantially less than the former study (from 62.8% to 52.3%). The change in herd size effects was mainly due to improved accuracy in the detection of oestrus in larger herds probably associated with the use of tail paint. On average, 50% of cows in 35 Waikato herds had calved by the end of a period of 18.3 d from the date of planned start of calving. The next 25% of cows calved over a period of 17.5 d, and the last 25% calved over 36.3 d. Consequently, the average calving covered 71.9 d from the planned start compared to 46 d in the Ruakura No.2 herd. A comparison with results from a 1972 survey showed that calving patterns had become more concentrated because of improved breeding management and the use of induced calving.

Selection for productive traits on back fat depth in ewe lambs - McEwan JC; Fennessy PF; Clarke JN; Hickey SM; Knowler MA (Proceedings of the New Zealand Society of Animal Production, 1984)
No abstract supplied.

Sodium requirements of grazing livestock - Towers NR; Young PW; Smeaton DC (Proceedings of the New Zealand Society of Animal Production, 1984)
Experiments were conducted for monthly periods during the spring and summer and autumn of 1982-83 with lambs fed on pastures from limed (pH 6.1) and unlimed (pH 5.5) areas. Lambs were offered herbage allowances 1, 2, 3, 4 or 5 kg DM/d on both limed and unlimed areas (10 groups of 10 lambs). Pasture composition remained similar between the 2 areas as did in vitro digestibilities of the pasture on offer. Limed pasture showed an increase in Ca and Mo and a decrease in Mn compared with the unlimed. Lamb live-weight gains were similar between limed and unlimed groups at all levels of herbage allowance over the 3 seasons suggesting that herbage quantity rather than quality was the major factor affecting the growth rate of the animals.

Some rumen characteristics and performance data of cows differing in bloat susceptibility - Carruthers VR (Proceedings of the New Zealand Society of Animal Production, 1984)
This paper reviews some of the recent developments in genetic and embryonic engineering and attempts to assess their likely impact on animal breeding theory and genetic improvement programmes. The distinction is made between genetic and embryonic engineering.

Spring-summer grazing management on hill country: effects on ewe performance - Smeaton DC; Wadams TK; MacKisack BD; Winter RD; Miller CM; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1984)
The soil type is an important factor influencing the occurrence of trace element deficiencies in grazing animals in New Zealand. Cobalt and selenium deficiencies occur mainly on soils from acidic rocks. Cobalt deficiencies may also occur on soils from more basic parent materials where the soils have been strongly leached. Selenium deficiencies is less easily predicted on the basis of soil characteristics. Copper deficiencies are more likely in stock grazing on peat soils, gley soils, certain pumice soils, saline soils, recent soils and some steepland soils. For all 3 elements, classification of occurrences of deficiency by soil type has provided a basis for delineating areas where deficiencies are likely, areas where they are unlikely and areas of marginal status. This has enabled a rational approach to investigations and the application of treatment and control measures.

Sward conditions, herbage allowance and animal production: an evaluation of research results - Hodgson J (Proceedings of the New Zealand Society of Animal Production, 1984)
Sixteen kids, 16 lambs and 16 calves approximately 4 months of age were allocated at random in balanced groups of 4 per species at a common allowance to 4 herbage masses (1800, 3000, 3900 and 5000 kgDM/ha) on a ryegrass white clover sward. A further calf, lamb and kid and a mature goat and ewe, fitted with oesophageal fistulas, grazed continuously with their own species at each herbage mass during the 8 day trial. These fistulated animals were randomly relocated to herbage masses every 2 days so that individuals sampled each herbage mass. On similar swards the diet of the lamb contained a greater proportion of clover (+0.23) and a smaller proportion of grass (-0.19) and dead material (-0.03) than the calf. The diet of the kid was intermediate between that of the lamb and the calf. The extent of dietary overlap suggests the species are in a major way competitive rather than complementary when grazing intensively managed swards. While older goats consumed a diet similar in composition to the young goat, older sheep consumed more dead material than lambs, although the proportions concerned were small. There was no difference in the in vitro digestibility of the diet selected by young goats, lambs and calves even though there were differences in botanical composition of the diet selected among the species. The in vitro digestibility of the diet selected was not affected by age of animal.

Synchronisation and artificial insemination of ewes - techniques which have possible commercial application - Harvey TG; Johnson DL; Tervit HR; Welch RAS (Proceedings of the New Zealand Society of Animal Production, 1984)
Mature ewes, 110 to 125 days pregnant, had catheters surgically implanted into maternal and foetal blood vessels and electrodes sutured to the myometrium. Electromyographic (EMG) signals were amplified, rectified, integrated and recorded. Between 2 and 12 days before parturition, the EMG pattern comprised bursts of activity that lasted 6.3

Terminal sire comparisons of the Charolais and Murray Grey breeds for calving difficulty, calf survival and growth - Morris CA; Baker RL; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 1984)
An enzyme-linked immunosorbent assay (ELISA) system has been developed for the detection of an endophytic fungus of Lolium perenne. The technique has been used to demonstrate quantitative differences in the spatial and tissue distribution of the endophyte in vegetative and reproductive tillers of infected plants. The influence of this on pasture toxicity is discussed. The nature of the endophyte antigen is described and the relationship between the antigen and toxicity discussed.

Theoretical considerations for partitioning nutrients between muscle and adipose tissue - Waghorn GC; Wolff JE (Proceedings of the New Zealand Society of Animal Production, 1984)
Calorimetry apparatus was used to measure CO2 production and oxygen consumption in 2 Romney and 2 Southdown ewes. Each pair consisted of a long-lean ewe and a short-fat ewe as determined from previous records of height, length, weight and ultrasonic back fat thickness. The respiratory exchange ratio (RER) was calculated as the ratio of CO2 produced/d to O2 consumed/d. When the 4 ewes were fed, the RER remained about 1, characteristic of the oxidation of glucose and short chain fatty acids. When the ewes were fasted for 4 to 5 days the RER declined in a straight linear fashion with time. This is consistent with the mobilisation of long chain fatty acids. The ewes of fatter genotypes exhibited significantly steeper regressions of RER on time.

Trace element deficiencies - a new approach to diagnosis - Wright DF; Clark RG; Millar KR; Rowland JD (Proceedings of the New Zealand Society of Animal Production, 1984)
Responses to sodium supplements have been recorded in trials with weaner Angus calves and mature ewes grazing pastures containing Na concentrations exceeding the minimum dietary levels calculated from recent Agricultural Research Council (1980) recommendations. Increased live-weight gains were noted following supplementation of calves grazing pastures with a Na content of 1 g/kg DM, and in ewes on pasture with 0.7 g/kg DM. These results suggest that either the estimates of daily Na requirements are too low or that for Na availability is too high.

Variations in milkfat test, liveweight, colour and height associated with the use of Friesian sires in some New Zealand dairy herds - Macmillan KL; Henderson HV; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1984)
Sixteen high (HS) and 16 low (LS) bloat susceptible dairy cows were offered hay or pasture when not lactating and pasture or 75% pasture 25% hay when lactating. There were no significant differences between susceptibility groups in voluntary intake or apparent digestibility of DM, OM, nitrogen or energy on either occasion. There was a trend for HS cows to produce less milk of higher fat, protein and lactose content than LS cows. Rumen digesta studies on 5 HS and 5 LS rumen-fistulated, dry, pregnant cows at a maintenance level of feeding indicated that the proportion of digesta lost from the rumen after feeding was higher for LS cows than HS cows on pasture, but not on hay. There was no significant difference between susceptibilities in post-feeding fluid dilution rate. HS cows tended to have higher rumen fluid osmolality and Na concentration during the post-feeding period on pasture, but not on hay.

Voluntary intake, testes development and antler growth patterns of male red deer under a manipulated photoperiod - Suttie JM; Corson ID; Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1984)
Two experiments studied the effects of herbage allowance in the latter half of pregnancy on the performance of 18-month beef heifers. In Experiment 1, 54 heifers were offered daily allowances of 4.5 (H) or 3.3 (M1) kg DM/100 kg live weight (LW), and in Experiment 2, 64 heifers were offered 3.1 (M2) or 1.9 (L) kg DM/100 kg LW. Average daily gain to post-calving weight (net ADG) for the H and M1 heifers in Experiment 1 was 0.46 and 0.34 kg/d (P<0.001). The post- partum anoestrous interval (PPAI) was short in both groups (H+ 42.7 and M1 = 49.2 days; P<0.10). H calves were 1.8 kg heavier at birth and 7.6 kg heavier at weaning than M1 calves (P<0.05). In Experiment 2, M2 and L heifer net ADG was 0.23 and -0.03 kg/d respectively (P<0.001). The PPAI was 28.4 d shorter for M2 than L heifers (P<0.001). Birth and weaning weights of M2 calves were heavier by 1.8 kg (P<0.07) and 14.0 kg (P<0.05) respectively than those of L calves. Results suggest that a herbage allowance of around 3 kg DM/100 kg LW over the latter half of gestation may be adequate for satisfactory performance of yearling-mated heifers.

Animal Research - time for a new approach - Fennessy PF (Proceedings of the New Zealand Society of Animal Production, 1983)
In each of 2 years Coopworth ewes were randomised to 8 groups which were offered 2 levels of herbage allowance (1.0 and 5.0 kg DM/ewe/d) from mixed pasture for varying periods during the 6 weeks prior to a synchronised mating. The ovulation rates of ewes fed at the lower allowance and then given the higher allowance for periods of 1 or 2 weeks prior to mating were not different from those fed continuously at the lower allowance. Ewes offered 3 weeks at the higher allowance showed a 25% increase in ovulation rate irrespective of when in the 6 week period this was received. Thus a minimum carry over period of 3 weeks was obtained. A further 30% increase in ovulation rate was obtained when ewes were offered the higher allowance for the full 6 week period. The proportion in ovulation rate was obtained when ewes were offered the higher allowance for the full 6 week period. The proportion of ewes lambing multiples was lower for those receiving <3 weeks high level feeding than for those receiving at least 3 weeks (33.5% v 56.0%; P<0.001), but there was no additional response to feeding at the high level for 6 weeks.

Behaviour factors influencing the rearing of Sahiwal-cross calves - Ward JDB; Bremner KJ; Kilgour R (Proceedings of the New Zealand Society of Animal Production, 1983)
The basic technique for freezing cattle, sheep and goat embryos is briefly described. The number of offspring born from each transferred thawed embryo is usually satisfactory but extensive pre and post freezing culling of embryos means that the technique is usually inefficient compared with unfrozen embryos. Research to improve results continues and the 54 and 64% embryo survival/embryo frozen obtained from minimally selected sheep embryos at Ruakura is most encouraging. The technique is being used for the international export of cattle embryos. Its major advantage is that it enables the export of genetic material which could not otherwise be obtained by the importing country. Its use should increase as embryo survival rates increase and particularly if it is established as an effective means of infectious disease control.

Changes in the salivary sodium:potassium ratio in lactating cows in response to changes in sodium intake - Towers NR (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Comparison of well and poorly muscled lamb carcasses as selected by experienced meat industry personnel - Kirton AH; Woods EG; Duganzich DM (Proceedings of the New Zealand Society of Animal Production, 1983)
Ten lambs and 10 kids were offered a low quality meadow hay (7.1 gN/kg/DM) for 12 weeks. Five of each species were then reallocated to lucerne hay (23.8 gN/kg/DM) and the remainder maintained on meadow hay. Feed was offered ad libitum. Digestibility was determined at weeks, 4, 6, 10 and 16. Animals were fed at 2 h intervals prior to slaughter and the retention time of dry matter in the rumen estimated. Body energy changes were estimated by comparative slaughter. In the initial 6 weeks kids and lambs digested meadow hay to a similar extent but whereas it was maintained in kids, digestibility by lambs subsequently declined until week 16. At week 16 values for dry matter digestibility were 0.67 and 0.54 for kids and lambs, respectively. There were no significant differences in the digestibility of lucerne hay between the species nor in the voluntary intake of meadow hay or lucerne hay. Both species consumed more lucerne hay than meadow hay. Kids retained lucerne hay longer than did lambs (18.,7 h and 11.8 h, respectively) but meadow hay had a similar retention time in both species (24.7 h and 27.8 h, respectively). Water intake of lambs was approximately double that of kids. Difficulties in determining maintenance energy requirement from body weight change are discussed.

Dags - cost thereof - MacKereth VJ (Proceedings of the New Zealand Society of Animal Production, 1983)
A number of facets of artificial insemination in sheep were studied at Rotomahana Research Station. The trial was a 2

Date of lambing and sheep production during lactation in Southland - McEwan JC; Mathieson C; Hawker H (Proceedings of the New Zealand Society of Animal Production, 1983)
In a series of 10 trials involving over 5000 lactating dairy cows, animals inseminated when detected in oestrus from 3 days after an injection of a prostaglandin F2a (PGF) had an average pregnancy rate of 68% compared to 59% in untreated herdmates. The variation in the post injection interval to oestrus necessitated detecting oestrus before the PGF-related fertility effect could be repeatedly demonstrated. When a synthetic analogue of gonadotrophin releasing hormone (GnRH) was injected before PGF in an attempt to reduce the variation in this injection-to-oestrus interval, the opposite effect occurred, the average interval was increased by 3 days (4.13 v 7.03) and the PGF-related fertility effect was eliminated. A second trial with GnRH confirmed that an injection of this hormone had an effect on the corpus luteum which prevented complete luteolysis by PGF. This interaction between GnRH and the corpus luteum was studied in 3 further trials in which GnRH was injected once at from 1 to 13 days post insemination. Positive fertility effects were observed in each trial, but they were not consistent. Nonetheless, the strategic use of these 2 types of hormones offer prospects for significantly increasing pregnancy rates to first insemination in lactating dairy cows.

Development of a performance test for the selection of rams having facial eczema-tolerate progeny - Towers NR; Meyer HH; Campbell AG; Southey CA (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Differences in the extent of mammary development between Jersey cows of high or low genetic merit - Brief Communication - Davis SR; Hughson GA; Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1983)
The effect of feed allowance (approximately 150 and 250 g green DM/kg live weight 0.75/d) and season (sampling at 12-week intervals) on objectively measured wool characteristics of Cheviot, Drysdale and Romney hoggets was examined. Improved feeding increased wool growth rate, fibre diameter and brightness. Feeding level did not affect fibre diameter variation, loose wool bulk or yellowness. Wool grew faster and was coarser during summer than during winter. Fibre diameter variation for the Cheviot and Romney was greatest in winter and least for the Drysdale in summer. There was no defined seasonal cycle for loose wool bulk. Colour indices were related to prevailing weather conditions. Maximum and minimum values for each characteristic were strongly correlated for fibre diameter and fibre diameter variation, weakly correlated for loose wool bulk and not consistently related for wool growth rate and colour indices.

Distribution of litter sizes within flocks at different levels of fecundity - Davis GH; Kelly RW; Hanrahan JP; Rohloff RM (Proceedings of the New Zealand Society of Animal Production, 1983)
Hogget lamb mortality in the Waihora sheep improvement programme from 1970/80 has ranged from 18 to 35% (mean = 24%). Hogget lambs born during the 1981 and 1982 lambings were used to study the timing, magnitude and causes of lamb mortality. Mean mortality to weaning were 33% and 28% in each year. The distribution of deaths was similar in each of the periods: at birth, born alive but died by day 3 and died between day 4 and docking. Dystocia was the single largest cause of deaths to day 3 accounting for about 13 lamb/100 lambs born. Birth weight was an important factor in lamb deaths with an optimum range of 3.3 to 4.1 kg for minimum mortality.

Effect of antioxidants on the toxicity of the facial eczema toxin, sporidesmin, in sheep - Munday R; Manns E; Mortimer PH (Proceedings of the New Zealand Society of Animal Production, 1983)
Zinc sulphate (0.35 g Zn/litre) in the drinking water of lactating dairy cows prevented the effects of both a mild natural spore challenge and the subsequent severe challenge of dosed sporidesmin. The changes recorded (serum gamma glutamyl transferase, liver and urinary bladder injury score, daily milk production and clinical and live weight changes) in the unprotected control group indicate considerable toxic injury whereas the changes in the group receiving zinc in drinking water were minimal indicating excellent protection. Water consumption records for the 2 groups did not indicate that the zinc treated water was substantially discriminated against.

The effect of breeding index on the performance of non-lactating Jersey cattle - Bryant AM (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Effect of feeding and season on fleece characteristics of Cheviot, Drysdale and Romney hogget wool - Sumner RMW (Proceedings of the New Zealand Society of Animal Production, 1983)
About 4000 ewes born over 3 years to single sire matings were repeatedly scored for incidence and severity of dags. Dag scores were analysed for evidence of genetic variation and relationship to structural and performance characteristics. Perendales were found to have lowest incidence of dags followed by Booroola x Perendales, Booroola x Romneys and then Romneys and Border Leicester x Romney ewes. There was no relationship between dag score and either wool or body weight characteristics, either within or between breeds. Among progeny of 6 Romney strain, daughters of Ruakura High Fertility rams had substantially lower incidence with little variation among the rest. It is suggested that long-term selection for fertility in this line has reduced incidence of dags through improved utilisation of forage, possibly as a result of resistance to internal parasites. The mean heritability of dag score was 0.31 with a range of 0.13 to 0.60, indicating that selection would be effective in reducing the incidence of dags and their associated costs to farmers.

The effect of pre-mating injection of an analogue of gonadotrophin-releasing hormone (GnRH) on pregnancy rates to first insemination in dairy cattle - Fielden ED; Moller K (Proceedings of the New Zealand Society of Animal Production, 1983)
The results of experiments with Friesian cows with breeding indices of 126 (HBI) or 102 (LBI) are presented. HBI cows produced an average of 153 kg milkfat/cow in the 1979 to 1981 lactations and LBI cows produced 125 kg milkfat/cow. HBI cows lost 0.7 of a condition score during lactation whereas LBI cows maintained their condition score. In 2 of the 4 staff feeding experiments the dry matter intake of pasture/kg 0.75 was significantly higher for HBI cows than LBI cows. There were no differences between the 2 groups of cows in their ability to metabolise dietary energy, nor in their heat production. JBI cows partitioned a greater proportion of their dietary energy to milk energy than LBI cows. Blood samples taken hourly for 24 h periods from cows fed indoors were analysed for growth hormone, insulin, glucose,

The effect of the duration and timing of flushing on the ovulation rate of ewes - Smith JF; Jagusch KT; Farquhar PA (Proceedings of the New Zealand Society of Animal Production, 1983)
Matched groups of ewe hoggets were mated to either fertile Southdown rams or vasectomised rams for a 6-week period in 1980 and 1981. The percentage of Romney, Coopworth and Perendale hoggets born in 1979 showing oestrus were 82, 92 and 92, and for those born in 1980 47, 84 and 79 respectively. The lower incidence of oestrus in those born on 1980 can be partly explained by lower hogget pre-lambing weights related to an outbreak of facial eczema in April 1981. Of hoggets joined to fertile rams, the percentages that weaned a lamb were 47, 60 and 67 for those born in 1979, and 13, 53 and 52 for those born in 1980. The percentages of two-tooths joined that weaned a lamb (average for those born in 1979 and 1980) were 71 for those not tupped as hoggets, 74 for those tupped by vasectomised rams, 53 for those tupped by fertile rams but not lambing, and 76 for those lambing as hoggets. There was no suggestion that hogget lambing impaired two-tooth reproduction, but those lambing produced 0.15 kg less wool at the two-tooth pre-mating shearing. The April 1981 GGT level of the 1980-born ewes was inversely related to live weight in April through to September 1981, and to percentage of ewes lambing as hoggets and as two-tooths, and to two-tooth pre-mating fleece weight.

Effects of cold exposure on chewing behaviour and rumen particle size in sheep given 4 diets - Kennedy PM (Proceedings of the New Zealand Society of Animal Production, 1983)
The rate at which the Na:K ratio of parotid saliva changes with changes in Na intake has been determined in lactating dairy cows. The salivary Na:K ratio of cows with an already marginal Na status fell immediately the animals were transferred to a Na deficient diet. Similarly the Na:K ratio of Na deficient cows incr3eased within days of Na supplementation reaching maximum levels after 2 weeks. The mean Na:K ratio for fully sodium replete cows was about 24 to 28:1, but there was considerable variation in the values for individual animals.

Effects of teasing and nutrition on the duration of the breeding season in Romney ewes - Knight TW; Hall DRH; Wilson LD (Proceedings of the New Zealand Society of Animal Production, 1983)
Proportions of ewes having 1 to 4 lambs in 72 local breed flocks with mean litter sizes per ewe ranging from 1.07 to 2.30 were examined, and compared with the proportions recorded in 12 groups of Booroola and 8 groups of Finn type ewes. Below a mean litter size of 1.70, differences in litter size resulted from differences in the proportion of ewes having singles and twins. Mean litter sizes ranging from 1.70 to 2.30 were accompanied by changes in the proportions of ewes having singles and triplets, the proportion of ewes having twins or quadruplets showing no significant change. The proportions recorded in local breed flocks and groups of Finn-type sheep were similar over litter sizes of 1.70 to 2.30. Groups of ewes that carried 1 copy of the Booroola gene had more ewes with 1, 3 and 4 lambs, but fewer ewes with twins, than the local breed flocks.

Ewe live weight, level of pasture feeding and live-weight gain - Thompson KF; McEwan JC; Kelly RW; Crosbie SF (Proceedings of the New Zealand Society of Animal Production, 1983)
The following farmer observations are based on limited numbers and are really a plea for more accurate work to be done. Loss from dags is difficult to cost but nationally it probably runs into millions in devalued wool and extra labour. On my own farm the direct loss is estimated to be about 63 cents/stock unit/annum. To reduce this loss I have looked at the following practices: 1. Breeding, limited observations - nil results. 2. Drenching. In two-tooths a drench pretupping reduced dags 44% in a 3 month period. 3. Docking tails longer was inconclusive, possibly due to a limited difference between 'long' and 'short' tails. 4. Mules operation. Result a 50% reducing between January and May. Mulesed sheep are easier to crutch by hand or machine. Sheep were apparently not knocked about by the operation. Although gory, mulesing is preferable to flystrike in terms of suffering. Uninformed and emotional public opinion is a problem. The greatest benefit of dag control or elimination may come from reduced flystrike.

Export of animals as frozen embryos - Tervit HR (Proceedings of the New Zealand Society of Animal Production, 1983)
Reproduction was compared in 2, 13-month weight-selection herds, Hereford (HS1) and Angus (AS1), in an 18-month weight-selection Angus line (AS2) and in an unselected Angus control (AC0), with ages at first joining in both sexes being 14, 14, 26 and 26 months respectively. Pregnancy rates (all ages, 5453 joinings) averaged 86, 88 and 90 and 86% respectively, so that yearling bull mating and/or weight selection have not disadvantaged the AS1 or AS2 lines. Sub-fertile bulls in the 3 selection lines numbered 5, 1 and 5 out of 59, 59 and 59 respectively. Calf death rates from 2-year-old AS1 heifers were lower than from 3- year-old first-calving AC0 heifers. The AS2 line weaned an adjusted total of 1005 calves (963, before adjusting by proportionally) from all age groups over 10 years, compared with 1239 calves in the AS1 line, a shortfall of 18.9%.

Fleece tenderness - a review - Bigham ML; Sumner RMW; Hawker H; Fitzgerald JM (Proceedings of the New Zealand Society of Animal Production, 1983)
The heritability of loose wool bulk and yellowness (CIE Tristimulus value Y-Z) and the genetic and phenotypic correlation of these with other wool traits were determined from data obtained on ewe hoggets born in 1979 and 1980 in the strains trial at Rotomahana. Heritability estimates were 0.41

Genetic variation in incidence of daggy sheep - an indicator of genetic resistance to parasites? - Meyer HH; Harvey TG; Smeaton JE (Proceedings of the New Zealand Society of Animal Production, 1983)
A recent grazing experiment at Ruakura with dairy cows involved in each of 3 years, 8 farms of 6.48 ha. Linear regression procedures were used to derive relationships between milkfat yield to 31 December, amount of feed on the farm at various times, length of rotation during winter months, and average herd live weight and condition at calving. Fat production was closely related to feed on the farm during July to September but not to feed present in May, June, October or November, or to live weight and condition at calving. The amount of feed present in August or September was not significantly related to that present in May. Feed present in September increased as the area grazed each day by the herd increased in May, and decreased in July and August. For a given amount of feed on the farm during July to September, early calving herds produced more milkfat per cow and per hectare by 31 December but at a lower level per day than late calving herds.

Genetic variation in uterine efficiency and differential responses to increased ovulation rate in sheep - Meyer HH; Clarke JN; Harvey TG; Malthus IC (Proceedings of the New Zealand Society of Animal Production, 1983)
Four antioxidants - butylated hydroxytoluene (BHT), butylated hyroxyanisole (BHA), alpha-tocopherol and propyl gallate - have been tested for their ability to ameliorate the harmful effects of the facial eczema toxin, sporidesmin, in sheep. A moderate decrease in sporidesmin-induced liver damage (39% and 35% respectively, based on gross pathological assessment of liver injury) was observed in sheep pre-treated with BHT and BHA; smaller effects were recorded in animals receiving the other compounds. The possibility of an additive effect between antioxidants and zinc has also been investigated. It was shown that marked protection against sporidesmin toxicity, significantly greater than that given by either prophylactic alone, was afforded by simultaneous administration of BHT and zinc.

Growth and carcass composition of Sahiwal-cross and Friesian bulls - Reardon TF; Woods EG; Ward JDB; Bass JJ (Proceedings of the New Zealand Society of Animal Production, 1983)
Two experiments were carried out in controlled temperature rooms, with Brahman x Friesian (F) calves aged 6 to 9 months exposed to 34

The heritability of loose wool bulk and colour traits and their genetic and phenotypic correlations with other wool traits - Bigham ML; Meyer HH; Smeaton JE (Proceedings of the New Zealand Society of Animal Production, 1983)
Twelve dairy farmers were taught a system of pasture scoring in May 1981. From then until the start of calving they assessed the amount of feed on their farms at fortnightly intervals. Milkfat production per hectare during the subsequent season was closely related to the amount of feed on the farm at the start of calving. Feed at calving was closely related to the amount of feed on the farm in May. The data suggest that milkfat production from most dairy farms is limited by having insufficient feed on the farm at calving.

Hogget lamb mortality - McMillan WH (Proceedings of the New Zealand Society of Animal Production, 1983)
Dorset ewes rearing twin lambs were offered herbage allowances of 2, 5 and 8 kg DM/ewe/d during a 6-week lactation period. Ewes and lambs were shifted at 3-day intervals. At 6 weeks lambs were weaned, combined into 1 mob and offered a fresh area of pasture ad lib every 3 days. Lambs were slaughtered at 6, 12 and 18 weeks of age. Carcass weight and fat measurements recorded. There were significant live-weight differences (2.5 kg) between low and high allowances during the trial, but differences in carcass weight were only significant at 6 and 18 weeks. Average growth rate between 6 and 18 weeks was 176 g/d in all groups. Fat measurements suggested no differences in carcass fatness between groups. It was concluded that herbage allowance preweaning had little effect on subsequent lamb growth and carcass fatness when ewes were shifted to new pasture at 3-day intervals.

Hogget lambing and its effect on the subsequent two-tooth performance of three breeds - Moore RW; Sumner RMW; Bass JJ; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1983)
Lamb survival and birth weight data from a Booroola x Romney flock and a Booroola x Merino flock were collected between 1975 and 1981. The mean litter sizes for these flocks were 1.96 and 1.76 respectively, with litter sizes ranging from 1 to 4 within each flock. Effects of year, ewe age, birth rank and birth weight on lamb survival were assessed by fitting a sequence of logit models to the data. Birth weight was identified as the key parameter, with year and birth rank effects being markedly reduced once the variability due to birth weight was accounted for. An apparent ewe age effect was completely explained in terms of lamb birth weight. At any given birth weight lambs born to large litters (>/-3) had a lower probability of survival than contemporary lambs born as singles or twins.

The importance of the amount of feed on the farm at calving to seasonal milk production - Phillips TI (Proceedings of the New Zealand Society of Animal Production, 1983)
A simple stocking rate model was used to derive stocking rates that maximise milkfat/ha and profit/ha. A study of recent changes in the cost/price structure indicates that economically optimal stocking rates are determined mainly by the parameters of the milkfat/cow- stocking rate relationship and are relatively insensitive to even large changes in the cost/price structure. Farmers' options of holding costs and adjusting stocking rates are discussed. Finally, an example is used to demonstrate the use of the method with research data and to illustrate factors worth considering in designing and interpreting trials to assess the value of a management input. Future trials should be run at stocking rates designed to describe production-stocking rate relationships rather than to accentuate treatment differences

The improvement and export potential of Bali cattle (Bos bibos-banteng) - Packard PM (Proceedings of the New Zealand Society of Animal Production, 1983)
Teeth wear over a 12-month period was measured in young ewes of 9 Romney and crossbred genotypes. Animals of Border Leicester breeding had higher-than-average wear rates and Merino-derived animals showed lowest wear. Genetic variation among genotypes and sires within genotypes accounted for the majority of explainable variation in wear rate. The pooled heritability estimate for teeth wear was 0.46

Increasing pregnancy rates in New Zealand dairy cattle - Macmillan KL; Taufa VK (Proceedings of the New Zealand Society of Animal Production, 1983)
Data from 4 experiments involving comparisons of cows of high (HBI) and low (LBI) breeding index summarised. In 2 stall feeding experiments, the differences (H-L) in daily intake (kg DM/100 kg LW) were -0.08

Influence of herbage allowance during the suckling period on subsequent growth and carcass fatness of twin lambs weaned at 6 weeks of age - Munro JM; Geenty KG (Proceedings of the New Zealand Society of Animal Production, 1983)
The effects of date of lambing (6 September, 23 September, 6 October) and rearing category (singles, twins) on ewe and lamb live weights and ewe wool production were examined in 1981 and 1982. Later lambing increased lamb growth in the first 6 weeks of lactation from 208 to 279 g/head/d for singles and 135 to 215 g/head/d for twins (P<0.001). Lambing date did not significantly affect lamb live weights at weaning on 5 January. Later lambing increased ewe greasy wool production between June and January by up to 0.41 kg (P<0.001).

Inheritance of wear rate in the teeth of sheep - Meyer HH; Aitken WM; Smeaton JE (Proceedings of the New Zealand Society of Animal Production, 1983)
Ovulation rate records from female progeny of 3 Booroola-type rams and the daughters of 8 to 10 male progeny of the same rams were recorded in commercial flocks. When a segregation criterion of at least 1 record of ovulation rate >/-3 was used to identify carriers of the putative gene, the results support the hypothesis of genetic segregation for fecundity in Booroola sheep. A comparison of the genotype ascertained from progeny tests with that estimated from the parental genotypes showed that 21 of 22 rams' performance was consistent with a single gene effect.

Intake, digestibility and retention time of 2 forages by kids and lambs - Alam MR; Poppi DP; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1983)
Fifty New Zealand Romney lambs (25 wethers and 25 ewes) grazing a ryegrass/white clover pasture from weaning, were used to study the distribution of zinc, copper, manganese and iron among the various organs and tissues and the amounts associated with a kilogram gain in fleece-free empty body weight. Each kilogram gain in fleece-free empty body weight was associated with 24 mg Zn, 0.77 mg Cu, 0.47 mg Mn and 55 mg Fe, while a kilogram of clean wool contained 220 mg Zn, 7 mg Cu, 3.5 mg Mn and 23 mg Fe. Thus for a young sheep gaining 100g of fleece-free empty body weight/d maintaining a mean wool growth of 10 g/d the daily demands for Zn, Cu and Mn for growth (2.4 mg Zn; 0.08 mg Cu; 0.05 mg Mn) and wool production (2.2 mg Zn; 0.07 mg Cu; 0.035 mg Mn) were found to be similar.

Integrating livestock and sugar-ethanol production and the dairy industry in Northland - a concept - Piggot GJ (Proceedings of the New Zealand Society of Animal Production, 1983)
Suffolk and Southdown rams were selected on the basis of high (H) and low (L) ultrasonic fat depths over the loin, adjusted for live weight. Rams were mated to Romney ewes and progeny were slaughtered at 2 ages. Loin fat depth (C) adjusted for carcass weight by 0.31

Large scale live breeding sheep exports- Brief Communication - Tavendale JB (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Livestock exports: animal health implications - Schwarz G (Proceedings of the New Zealand Society of Animal Production, 1983)
There is a dearth of useful performance data on exported New Zealand-bred animals. Expectations vary as to what is required of these animals and breed comparison trials involving them in foreign environments are rare. Care must be taken to avoid the 'bigger is better' syndrome in judging the performance of exports. New Zealand genotypes adapt to foreign temperate environments and perform according to level of management. New Zealand dairy cattle, pigs and poultry can perform well in tropical environments if managed intensively. Crossbreeding between imported and local, adapted genotypes of cattle and sheep would seem to be the best way to use New Zealand germplasm in tropical countries. The use of Zebu semen on New Zealand cows to produce tropically adapted crossbreds for export is proving successful but such cattle are unlikely to outproduce exotic x local crossbreds. There is a need for information to enable better choice of breeds for crossbreeding and the development of breeding plans to enable importing countries to make best use of exotic genes.

Livestock exports: exporter's viewpoint - Wallace RD (Proceedings of the New Zealand Society of Animal Production, 1983)
The role of the Animal Health Division of the Ministry of Agriculture and Fisheries in the export of animals is outlined. New Zealand's freedom from serious animal diseases and the high quality of its livestock are the major factors contributing to the steady overseas demand for animals. The animal health conditions of importation are variable and often require considerable negotiation before they are acceptable to both New Zealand and the importing country. Veterinary officers have a dual role - to -protect the importer and to assist the exporter and there has to be constant liaison and cooperation at all levels to ensure a successful fulfilment of export orders. Animal welfare is a major consideration at all stages of the operation.

Livestock exports: national economic significance - Gould MD; Baigent PN (Proceedings of the New Zealand Society of Animal Production, 1983)
Much of the non-arable area of South Korea is suited to the establishment of permanent improved pasture. In 1974 the New Zealand Government began a co-operative project to establish a pasture based beef cattle farm on 354 ha in the alpine region of South Korea. Two hundred Hereford and Angus breeding stock were sent from New Zealand to form the foundation herd for the project. The pr9oject's extension programme included 25 private farms. Permanent pastures comprising perennial ryegrass, cocksfoot, timothy, white and alsike clovers were successfully established following the fencing and mobstocking of scrub with the application of fertiliser. New Zealand cattle showed superior growth rates to native cattle in the temperate climate. No major disease problems were encountered. Continuous grazing during the 6 months of pasture growth and the conservation of surplus pasture as hay or silage for winter provided adequate nutrition for the spring calving herd.

Livestock exports: past present future - Callow AV (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Livestock exports: the advisors' and farmers' view - Dawson JE (Proceedings of the New Zealand Society of Animal Production, 1983)
At least 6 different species of animals are currently being exported from New Zealand, horses, cattle, sheep, goats, pigs and poultry. Of theses only horses, cattle and sheep are of economic significance. Although the volume and value of livestock exports has increased dramatically in percentage terms over recent years, returns from total livestock exports still amount to less than 1% of total exports. It is anticipated that dairy cattle exports in particular could continue to increase in geometric terms. Scope also exists for increased exports of other species but they will be subject to more constraints. While livestock exports are useful in a national economic sense and are important to individuals, companies and some geographic areas, it is unlikely that they will amount to any national economic significance in the foreseeable future. It is unlikely that livestock exports will adversely affect overseas markets for New Zealand animal products. Rather, the resulting expansion in local production is likely to stimulate consumption, leading to consumer pressure to increase imports to satisfy this demand.

Livestock exports: the role of the thoroughbred - Hogan P (Proceedings of the New Zealand Society of Animal Production, 1983)
The types and economics of each contract for export animals are discussed and examined from the advisers' and farmers' view. The good returns in 1982 for rearing of qualifying Friesian heifers calves are indicated together with the various margins for Sahiwal options. Data is presented from a survey which has shown an adoption rate for the Sahiwal scheme of 22% with 66% of adopters continuing with it. Reasons for non-adoption are discussed, as are also industry considerations of this recent and developing market, particularly those affecting dairy processing and the domestic market for dairy heifers.

A low cost method of artificially rearing lambs at pasture - Smith MC; Geenty KG (Proceedings of the New Zealand Society of Animal Production, 1983)
A Poll Dorset flock was mated naturally in spring for 4 years. As lambing date shifted from mid June to mid April overall flock fertility declined but fecundity did not change greatly. Ewes lambing in mid April were under less feed stress during lactation than ewes lambing in late May. Integration of the flock with spring lambing ewes was made easier with a more concentrated lambing pattern in autumn. As lambing date changed from 24 May to 12 April, lamb growth rates in winter declined. However, more than 84% of the lambs reached 30 kg live weight by mid November. High faecal egg counts were recorded in April born lambs before weaning.

The management of New Zealand beef cattle exported to South Korea - Davis GH; Lewis KHC; Matheson DE (Proceedings of the New Zealand Society of Animal Production, 1983)

Nutrition and management of ewes before and after lambing - Smeaton DC; Rattray PV; MacKisack B; Heath S; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1983)
Lambs were offered low (180g DM/d) or high (320 g DM/d) allowances of cold ewe milk replacer until they reached live weights of 9 or 12 kg. Growth performance before and after weaning was compared with that of single-suckled lambs weaned at the 2 corresponding live weights. Growth rates of lambs offered a high milk allowance were greater than for those offered a low allowance and were similar to those for suckled lambs. Low milk allowance groups showed a relatively smaller growth check following weaning. The major factor affecting post weaning live weights was weaning weight; lambs weaned at 9 kg weighed, on average, 18.4, 24.9, 34.8 and 42.5 kg respectively at 12 weeks, 18 weeks, 12 months and 15 months of age and those weaned at 12 kg weighed 20.3, 27.1, 36.3 and 44.7 kg at the corresponding ages. It was concluded that the use of cold ewe-milk replacer and the encouragement of lambs to consume herbage at an early age provided a low cost, low labour method of artificially rearing lambs.

Nutritional and physiological studies of differences between Friesian cows of high and low genetic merit - Davey AWF; Grainger C; MacKenzie DDS; Flux DS; Wilson GF; Brookes IM; Holmes CW (Proceedings of the New Zealand Society of Animal Production, 1983)
Fleece tenderness is a serious fault of New Zealand crossbred wool costing the sheep industry between $50 and $100 million annually. Wool fibres break at the point where fibre diameter is at its minimum and factors which influence minimum fibre diameter will influence the incidence of fleece tenderness, e.g. breed and strain of sheep, age of ewe, level of feeding and reproductive status. Tender fleeces are on average lighter than sound fleeces and often have other associated faults such as cotting and yellow discolouration. Variation in minimum winter fibre diameter accounts for only about 40% of the variation in staple strength within a flock suggesting that factors other than fibre diameter may be involved. There are fibre structural and compositional differences between sound and tender wools of the same diameter and these may be associated with fleece tenderness. The wool producer can influence the incidence of fleece tenderness by the level of feeding during mid pregnancy but it may not always be economic to feed better. Choice of shearing time will also influence the level of fleece tenderness. A preliminary estimate of the heritability of fleece tenderness of 0.58

Patterns of lamb survival in high fecundity Booroola flocks - Hinch GN; Kelly RW; Owens JL; Crosbie SF (Proceedings of the New Zealand Society of Animal Production, 1983)
In Trial 1, ewes were fed high or low nutrition in mid and late pregnancy and post lambing until docking in a 2

Performance of an autumn lambing Poll Dorset flock in Northland - Andrewes WGK (Proceedings of the New Zealand Society of Animal Production, 1983)
Seven trials were conducted during 3 breeding seasons where half the animals in each trial herd received a subcutaneous injection of 10

Performance of New Zealand-bred animals in foreign environments - Quartermain AR (Proceedings of the New Zealand Society of Animal Production, 1983)
Growth rates of Sahiwal-cross (S x F) and Friesian (F) bulls were compared in 2 experiments. In the first, 40 F and 38 S x F bulls were slaughtered at a carcass weight of about 230 kg and the left side of each carcass was jointed and dissected into meat, fat and bone. The 2 breed groups were grazed at equal levels of pasture allowance from 17 weeks of age when F calves (124 kg) were 30 kg heavier than S X F. After 17 weeks of age, F bulls gained live weight and carcass weight faster than S X F and were slaughtered 9 weeks earlier. Mean weights of carcass, of carcass corrected for live weight and of fore- and hindquarters, were the same for the 2 breeds. However, S x F carcasses had more meat (72% v 71%), more fat (8% v 6%), less bone (20% v 22%) and consequently a higher meat:bone ratio (3.55 v 3.18) than F carcasses of the same weight. In the second experiment 24 F and 24 S-cross bull calves were grazed as 1 mob from 20 weeks of age when both breeds had a mean live weight of 96 kg. From then until 55 weeks of age F and S-cross bulls grew at similar rates (0.59 and 0.56 kg/d respectively). From 55 to 67 weeks, F bulls grew slightly faster (1.26 and 1.18 kg/d respectively).

Quantities of zinc, copper, manganese and iron associated with body weight gain and wool growth of young sheep - Grace ND (Proceedings of the New Zealand Society of Animal Production, 1983)
No abstract supplied

Ram induced stimulation of ovarian and oestrous activity in anoestrous ewes - a review - Knight TW (Proceedings of the New Zealand Society of Animal Production, 1983)
Seventy-nine Romney ewes were allocated to high (H) or low (L) pasture allowances from 27 January. Half of each group (R) was joined with teaser rams on 9 February while the other half (I) remained isolated from rams until 10 March. R ewes exhibited oestrus 13 days earlier than the I ewes but there was no effect of nutrition. L ewes had fewer oestruses than H ewes (7 v9) and more abnormal oestrous intervals (16% v 7%). There was a negative relationship between number of oestruses and GGT levels and a positive relationship with live weight. There was no effect of teasing on the number of oestruses, thus R ewes returned to anoestrus 16 days earlier than I ewes. Similarly L ewes returned to anoestrus 20 days earlier than H ewes.

Relationships between amount of feed on the farm, autumn-winter grazing management and dairy cow performance - Bryant AM; MacDonald KA (Proceedings of the New Zealand Society of Animal Production, 1983)
A selection experiment which has resulted in dairy cows of extremes susceptibility to bloat is reviewed. The low susceptibility cows had a higher liquid milk production and a lower milkfat percentage than the high susceptible ones. They showed little or no bloat on highly potent pastures. Comparison of the herds was directed towards physiological differences and relationships which could explain the origin of low susceptibility and lead to phenotypic definition useful for selection. Some differences were found in proportions of salivary proteins and progress has been made in their separation, definition and measurement. In vitro experiments have not indicated sufficient differences in gas or foam production per litre of rumen fluid to explain bloat grade variation but observation followed by direct experiment has shown that a greater volume of rumen fluid is associate4d with a high susceptibility to bloat. This could form a basis for commercial selection if appropriate measurement methods can be devised.

Segregation of a major gene influencing ovulation rate in progeny of Booroola sheep in commercial and research flocks - Davis GH; Kelly RW (Proceedings of the New Zealand Society of Animal Production, 1983)
Superovulation with ova transfer (1979, 1980) and superovulation (without ova transfer) plus artificial rearing (1981, 1982) were used to establish flocks of Romney, Perendale and Coopworth sheep from fecund animals donated by farmers. In their first and second years respectively in the ova transfer programme, 39% and 32% of donor ewes failed to have any progeny by ova transfer, and 38% and 44% failed to lamb themselves while the mean number of lambs tailed per donor at joining was 2.68 and 2.21. In their first and second years respectively in the artificial rearing programme only 7% and 3% of ewes failed to produce a lamb with a mean number of lambs born per donor joined of 2.15 and 2.36. High lamb mortality rates (27% and 32% of lambs born) resulted in 1.58 and 1.64 lambs tailed/ewe/annum. About 40% of ewes failed to reach the objective of at least 2 live lambs/ewe/annum in both programmes.

Selection efficiency in ram breeding flocks - Dodd CJ; Delahunty JR (Proceedings of the New Zealand Society of Animal Production, 1983)
Genetic variation in ovulation rate, both within and between breeds, is recognised as a major source of variation in litter size, while breed differences in embryonic survival are generally assumed to be unimportant. Results reported here for several trials, years and locations and involving large numbers of naturally multiple ovulating ewes show significant and consistent genetic differences in the proportion of ewes producing 2 lambs following conception to twin ovulations (uterine efficiency). Compared to contemporary Romneys (uterine efficiency = 0.59), 4 to 34% more ewes of 5 other genotypes produced twin lambs following conception to twin ovulations. At the extreme, Border Leicester x Romneys ranged from 24 to 52% superior in 3 comparisons. At ovulation rates higher than 2, inter-ovarian ovulation pattern was also found to influence litter size. Increasing disproportionality of ovulation rate between ovaries resulted in lower litter size. This may be due to uneven distribution of implantation sites and increased losses due to crowding.

Selection for and against susceptibility to bloat in dairy cows - a review - Cockrem FRM; McIntosh JT; McLaren R (Proceedings of the New Zealand Society of Animal Production, 1983)
Experienced meat industry personnel selected lamb carcasses categorised as either well muscled, average muscled or poorly muscled, so that a more objective specification of the carcasses meeting these different descriptions might be made. Well muscled carcasses were found at the blocky (E) end and poorly muscled carcasses toward the middle (Av) of the MLC conformation scale. Poorly muscled carcasses had the longest F, T, cut-leg length, carcass length and M. longissimus dorsi length measurements when compared at similar weights with the other muscling classes. Well muscled carcasses tended to have the highest fat percentage and lowest bone content. There was no difference in muscle content between carcasses of the different muscling types. This ability to recognise muscle content in lamb carcasses may explain the absence of a premium from the meat industry for carcasses with a higher muscle content despite consumer research suggesting that more muscle and less fat is required.

Some effects of hot conditions on Brahman or Sahiwal crossbred calves - Holmes CW; Hughes TP; King CG; Sauwa PEL; Auko PSA (Proceedings of the New Zealand Society of Animal Production, 1983)
New Zealand is involved in the improvement of the Bali breed of cattle in Indonesia through a bilateral aid project. From 1977/82 significant improvement has been achieved in the Bali Cattle Development Project - 5 kg, 6 kg and 22 kg improvement in weaning, yearling and rising 2-year-old live weights respectively and 21% improvement in calving percentage. Establishment of a central breeding herd of elite Bali cows is planned with top performance and progeny tested bulls being made available to the local farmers through artificial breeding. The unique qualities of Bali cattle enhances its export potential throughout many tropical and subtropical countries of South-East Asia and the Pacific.

Sporidesmin concentrations in the bile of sheep resistant or susceptible to sporidesmin dosing - Fairclough RJ; Smith BL (Proceedings of the New Zealand Society of Animal Production, 1983)
A practical performance test identifying rams siring progeny with greater than average tolerance to sporidesmin-induced liver damage (facial eczema) has been developed. The performance test, which can be conducted under field conditions using toxic pasture as the challenge, depends on measuring elevations in plasma gamma glutamyltransferase levels as a non-destructive way of assessing sporidesmin-induced liver damage. Selection for tolerance to facial eczema in commercial flocks is now feasible. Trial results indicate rapid responses to selection can be expected.

Stocking rate effects in dairying - Wright DF; Pringle RM (Proceedings of the New Zealand Society of Animal Production, 1983)
Arising from agronomic research into energy farming in Northland, a sugar-ethanol industry based on the crop sweet sorghum (Sorghum bicolor) has been proposed. The competitiveness of such an industry will probably depend on an integration with the processing functions of the dairy industry, and on the advantages gained from the increased animal production resulting from utilising the sugar-extracted crop residues. A theoretical analyses of dairy, sheep, and fattening beef systems indicated that a limit of 10% of the farm cropped in sweet sorghum annually would optimise the production and use of sugar-extracted crop residues based on the use of most of the residues as silage. If such material could be converted directly to increase stocking rate, a substantial rise in net farm income was predicted from growing sweet sorghum for sugar. Twenty Northland farmers were interviewed concerning on-farm aspects of this sugar industry concept. While limited in scope, this survey indicated a number of factors influencing further development of the concept, such as the importance of cropping contractors and independent technical advisors, and the doubt concerning the expected response from feeding crop residues to livestock.

Techniques to establish flocks from fecund ewes by superovulation with and without ova transfer - Kelly RW; Lewer RP; Allison AJ; Paterson A; Howarth M (Proceedings of the New Zealand Society of Animal Production, 1983)
Twelve ram lambs bred for resistance or susceptibility to sporidesmin dosing were operated on under general anaesthetic and T-way catheters inserted into the common bile duct to facilitate collection of bile. After a recovery period of 14 days the animals were given an oral dose of sporidesmin at a rate of 0.08 mg/kg/d over 3 consecutive days. A trace amount of 35S-labelled sporidesmin was also given on the first and third day of dosing to allow quantitation of sporidesmin appearing in the bile fluid. Bile samples were collected at 0.5 to 1 hourly intervals for 24 hours after the first and third dosing. Results showed bile concentrations of sporidesmin increasing to a maximum in 1 to 3 hours and then declining over the following 20 hours. There was considerable individual variation among animals in the pattern of uptake and in the maximal concentration reached after dosing. In some animals there was a marked increase in biliary sporidesmin from the first to the third oral dosing while other animals showed little observed increase at these times. A positive correlation (P<0.05) was found between liver- damage score at slaughter and maximum sporidesmin concentration in bile after the third but not the first oral dosing. These findings raise the possibility that an initial or 'potentiating' dose of sporidesmin may be required before 'susceptibility' or ' resistance' to facial eczema is expressed.

Ten years reproduction performance data from Angus and Hereford weight selection herds - Morris CA; Baker RL; Hunter JC (Proceedings of the New Zealand Society of Animal Production, 1983)
A sheep selection efficiency analysis developed to supplement recording on Sheeplan was applied to performance records in 8 groups- breeding scheme central flocks. Average flock size was 756 ewes, and 170 rams were selected from 4 birth-years for central flock use. Selection efficiencies for the Sheeplan two-tooth index were 64%, 74%, 70% and 68% for rams born in 1977/80 and the corresponding efficiencies for two-tooth ewes were 29%, 27%, 42% and 44% respectively. The selection of two-tooth ram and ewe replacements is expected to result in annual rates of improvement of 0.67% in lambing rate, 0.16 kg in weaning weight, 0.34 kg in hogget live weight and 0.029 kg in hogget fleece weight. Other traits breeders emphasised included structural soundness, wool quality and hogget lambing performance. Opportunities for increasing rates of progress in sire breeding programmes are discussed.

Ultrasonic selection for divergence in loin fat depth in Southdowns and Suffolks - Bennett GL; Meyer HH; Kirton AH (Proceedings of the New Zealand Society of Animal Production, 1983)
The physical breakdown of 4 forage diets in the chopped or pelleted form was studied in 16 closely-shorn wether sheep at room temperatures of approximately 24

The use of 'Lipiodol' for sub-clinical iodine deficiency in livestock - Brief Communication - McGowan AC (Proceedings of the New Zealand Society of Animal Production, 1983)
Over the 11-year period 170/81, the number of thoroughbred mares being bred from approximately doubled (4874 to 9894). This dramatic upsurge in the broodmare population cannot be accounted for by increased fertility, which has remained at approximately 72% since the early 1950s. Rather it reflects the apparent lack of culling taking place of genetically (progeny tested) inferior mares. Unlike other agriculture enterprises, where increased production is dependent upon increased numbers, the thoroughbred industry sells on a 'quality' rather than a 'quantity' image and over-production of inferior grade animals can be harmful. The success of the 'quality' image can be gauged by an excess of export earnings over imports in the order of $25m in the year ended 30 June 1982 ($29m exports, $4m imports). The exports were achieved by the sale of nearly 1800 thoroughbred stock to 12 overseas countries. The factors considered important in the production of 'quality' thoroughbred stock are: rigorous culling of non-commercial breeding stock; sound nutrition; yearling preparation techniques; reduction in fertility wastage of genetically superior stock; sound nutrition; yearling preparation techniques; reduction in fertility wastage of genetically superior stock; disease control; overseas promotion. The development of a New Zealand equine industry with a potential annual export earning capacity in excess of $100m will depend on these factors together with Government assistance in the area of export incentives, research in mare fertility, nutritional imbalances in young thoroughbreds and pasture management.

Zinc sulphate in the drinking water of lactating dairy cows for facial eczema control - Smith BL; Embling PP; Pearce MG (Proceedings of the New Zealand Society of Animal Production, 1983)
The live-weight response of light and heavy ewes to a range of pasture allowances was investigated in 3 experiments. Differential feeding levels prior to the commencement of Expt. 1 generated light and heavy ewes (52 v 57 kg live weight, P<0.001; 3.5 v 4.1 body condition score, P<0.01) that were subsequently offered pasture allowances of either 1, 2 or 4 kg DM/ewe/d for a 10-week period. Light ewes gained more weight than heavy ewes on all allowances. With time, ewes tended to approach a constant live weight in equilibrium with their level of feeding. Both light and heavy ewes harvested pasture to similar post- grazing residuals and rejected the dead material in the sward. In Expts, 2 and 3 low and high live weight ewes were selected from within large flocks of 4-tooth ewes that had been run as 1 mob (live weight 38 v 49 kg Expt. 2, 41 v 55 kg Expt. 3, P<0.001; body condition 1.8 v 2.4 Expt 2, 2.1 v 3.1 Expt, 3, P<0.01). Light and heavy groups were most grazed separately on allowances of 1.2 or 4 kg DM/ewe/d for 6 weeks although Expt. 3 partly comprised mixed groups for assessment of competition effects. No such effects were apparent on the higher allowance where light and heavy ewes had similar live-weight gains. On the lower allowance however, light ewes were more responsive than their heavier counterparts with this being less pronounced under mixed grazing. The implications for flock management are discussed.

Animal production from hill country: Effect of fertiliser and grazing management - Clark DA; Lambert MG (Proceedings of the New Zealand Society of Animal Production, 1982)
In each of 2 years mixed age Coopworth ewes (1978, 58 kg; 1979, 55 kg) were randomised immediately before lambing and offered a range of herbage allowances (2, 4, 6, 8 and 10 kg DM ewe) from mixed pasture of contrasting mass (1978, 2300 v 4140; 1979, 2100 v 3600 kg/ha) and lucerne (1978, 4390 kg/ha; 1979, 3000 kg/ha) until weaning at 10 weeks post-lambing. Final ewe weight, weight change, weight of lamb weaned per ewe and ewe fleece weight all increased with allowance. Lamb weaning weights started to level off above 8 kg DM/ewe but ewe gains and fleece weight continued to increase. On the higher-mass pasture ewes were lighter in 1978 and lambs were lighter in 1979. Lucerne-fed ewes lost more weight and produced less wool, but had similar (1978) or heavier (1979) lambs at weaning than pasture-fed ewes. The importance of feeding during lactation on lamb weaning weight was highlighted and management implications discussed.

An approach to advisory work with deer farmers in Southland - Brief Communication - Harbord MW (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

Biochemical events associated with Ficoll washing of ram spermatozoa - Jansen GJ; van Eerten MTW; Forrester IT (Proceedings of the New Zealand Society of Animal Production, 1982)
Changes in meat processing to comply with overseas and domestic hygiene requirements or to reduce costs and improve product quality are almost continuous. Electrical stunning, mechanical dressing, accelerated conditioning, shrink wrapping and further processing are discussed in relation to their impact for producers. Major meat processing changes that could affect either processing costs or increase the gross return for the products and thereby affect the return to producers are considered. Some of these changes require producers to modify their management practices to get the increased returns.

Blood plasma tryptophan concentration - a potentially useful indicator of feed intake in pasture-fed ruminants - Brief Communication - Davis SR; Hughson GA; McLeay LM (Proceedings of the New Zealand Society of Animal Production, 1982)
Mixed perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) pastures at Ruakura were sprayed with Mefluidide, a herbage growth retardant, in 3 consecutive spring periods from 1978. Pasture DM yields was markedly depressed at rates as low as 0.2 kg ai/ha and the effects were more marked with early season applications than those applied in late season. Mefluidide reduced the incidence of Poa annua L. in the swards and white clover was increased. In 1979/80, weaned lambs were set stocked on pastures sprayed with Mefluidide at 0.2 kg ai./ha. Live-weight gain/head was increased at each of 3 levels of pasture on offer. Pastures again contained less Poa annua and more white clover. In 1980/1 pastures were sprayed with Mefluidide at 0.2 kg ai/ha Ethofumesate at 0.2 kg ai/ha to eliminate clovers. Lamb gain was again increased on pastures sprayed with Mefluidide although 1 month after application fewer animals were carried at equivalent levels of herbage offer, due to lower herbage growth rates. It is concluded that Mefluidide enhances the herbage quality of perennial ryegrass/white clover pasture and that the technique has special application where per head performance is of paramount importance.

Calving behaviour of single-suckled Angus cows and their calves born in the spring - Aitken VR; Holmes RJ; Barton RA (Proceedings of the New Zealand Society of Animal Production, 1982)
Oversowing and top-dressing of a small area within a defined but unfenced part of a high country summer range caused sheep to concentrate on that treated area. Sheep density and grazing pressure were respectively 4 and 7 times greater than on the untreated area. As fewer sheep grazed the untreated area dry matter utilisation overall decreased in the following 2 years.

Central nervous system injury as a determinant of lamb mortality - Duff XJ; McCutcheon SN; McDonald MF (Proceedings of the New Zealand Society of Animal Production, 1982)
The aim of the present study was to establish whether ovulation and normal corpus luteum function could be induced in anoestrous ewes by supplementing the endogenous level of luteinizing hormone (LH) and whether cyclical ovarian activity could be induced and maintained in seasonally anoestrous ewes by an unvarying long-term intravenous pulse regime of gonadotrophic releasing hormone (GnRH), 500 ng once per 2 h or 43-80 days. The results demonstrated that a normal ovulation can be induced in anoestrous ewes with LH alone and that the aforementioned GnRH regime was successful in inducing cyclical progesterone activity. These findings suggest that normal breeding activity may be restored to anoestrous ewes when the frequency of hypothalamic GnRH is increased from an apparent endogenous level of secretory episode per 3.5 h to 1 episode per 2 h.

Characteristics of high performance flocks in Otago and Southland - Brief Communication - Rohloff RM; Davis GH; Hinch GN (Proceedings of the New Zealand Society of Animal Production, 1982)
Marshall Romney ewes had higher ovulation rates and percentage births than control Romney ewes. These differences were accounted for by the higher live weights of Marshall Romney ewes. Differential grazing in 1979 produced ewes with different condition scores and live weight but the same body size. Ovulation rates were higher in the heavier ewes with the higher condition score. Body size and condition score contributed approximately equally to the variation in the live weight and both accounted for a significant proportion of variation in ovulation rate. However live weight accounted for more of the variation in ovulation rate than body size and/or condition score.

Chemical and histological parameters associated with the tenderness of hemicastrate and steer beef - Hinch GN; Thwaites CJ (Proceedings of the New Zealand Society of Animal Production, 1982)
The fat thickness over the 12th rib was measured ultrasonically on 41 Coopworth ram lambs (7 months of age, 34 to 57 kg live weight). Four of the 7 fattest and 4 of the 7 leanest were selected on the basis of their deviations from the overall fat thickness - live-weight relationship. Ten to 12 male progeny of each of these rams generated from Perendale ewes were slaughtered at 4 to 7 months of age and 4 parameters of carcass fatness measured. The difference between the progeny of the 4 lean sires and that of the 4 fat sires was significant for 2 fat measurements, namely C (P<0.05) the backfat thickness over the 12th rib, and S2 (P<0.01) a fat depth in the shoulder region. Differences in GR and total chemical fat failed to reach significance. The data indicate that selection of sires on the basis of backfat thickness could be an effective means of reducing carcass fat thickness in lambs.

Comparison of backfat depth probes for use in pig carcass grading - Adam JL; Duganzich DM; Hargreaves K (Proceedings of the New Zealand Society of Animal Production, 1982)
Objective measurements in cattle accounted for a significant percentage of the variation of hindquarter muscle weight after adjustment for weight of hindquarter and within the N.Z. export P grade. The conformation measurements on lamb accounted for only a small percentage of the variation of the weight of muscle and fat-free frozen carcass weight. Objective conformation measurements in cattle may be of use in a grading system unlike the conformation measurements taken in sheep.

A comparison of the composition and carcass quality of Kelly and Russian castrate, ram, wether and ewe lambs - Kirton AH; Clarke JN; Hickey SM (Proceedings of the New Zealand Society of Animal Production, 1982)
Data on M. longissimus dorsi (LD) area, width and depth were examined on 1957 lamb carcasses graded for export as either P (moderate to heavy fat cover) or Y (light fat cover) over 3 slaughter seasons. Lambs were sired by 1 of 11 different breeds mated to Romney ewes. Carcasses in the 2 grades differed in mean weight and LD measurements in the different seasons. After adjustment for differences in carcass weight and the effect of sire breed, LD area did not differ between the P and the Y grades. After adjusting the A (width) and B (depth) measurements of differences in carcass weight and sire breed, P grade LD's were significantly narrower and deeper than those from the Y grade, but the differences were small (maximum of 5% for depth in 1970/1 season) and of little practical significance. Thus if the leaner Y grade carcasses are desired, and this is done on a within breed basis, the LD area or shape should not be adversely affected provided carcass weights are not reduced.

Diet selection by goats and sheep on hill country - Clark DA; Lambert MG; Rolston MP; Dymock N (Proceedings of the New Zealand Society of Animal Production, 1982)
Diet quality was measured using oesophageally-fistulated lactating Dorset ewes offered herbage allowances of 8 (H), 5 (M) and 2 (L) kg DM/ewe/d. Ewes on all allowances tended to have a similar selection preference for grass and clover; those on H and M allowances consumed proportionately more clover and less dead material than L ewes. The mean DDM of herbage selected by ewes in H and M groups averaged 0.790 and was 0.734 for L ewes compared with 0.727 for sward samples taken pre-grazing. The ME content of DM consumed by H and M ewes was 7% greater than for L ewes. It is suggested that the lower digestibility of the diets of L ewes was due to a higher consumption of dead material and plant stalk than in ewes on H and M allowances.

Differences between P and Y export lamb carcass grades in M. longissimus dorsi area and shape - Kirton AH (Proceedings of the New Zealand Society of Animal Production, 1982)
Fat depths were measured on the hot carcasses of 128 pigs, 64 steers and 106 lambs using an appropriate Fat-Depth Indicator (FDI). Corresponding linear depths were taken 4 cm (pigs), 8 cm (steers) and 3.5 cm (lambs) lateral to the dorsal midline in the region of last rib. Pig and steer carcasses were physically dissected into subcutaneous fat plus rind and trim fat respectively. Of fat depths taken on the hot carcass by FDI 72, 57 and 98% were within

Differences in grazing and milking behaviour in high and low breeding index cows - Arave CW; Kilgour R (Proceedings of the New Zealand Society of Animal Production, 1982)
Groups of Merino lambs, with or without their mothers, were exposed to whole grain wheat for periods ranging from 5 to 45 hours at different ages before weaning at 10 weeks. Acceptance of wheat was tested during the following week. Feeding behaviour was monitored during exposure periods and both behaviour and intake were recorded during 30 minute test periods on each of 5 days in week 11. Groups of lambs exposed together with their mothers, which regularly ate wheat, all ate; their intakes averaged 810 g/head over the test period. Another group, also exposed with their mothers, but mothers which had been first offered wheat during the week before exposure, all ate wheat; their intakes averaged 290 g/head. Most lambs exposed without their mothers ate very little or no wheat in the post-weaning test period. The results show that pre-weaning experiences, particularly those related to maternal or other adult influences, are strong determinants of feeding behaviour, at least in the short term. Post-weaning acceptance of wheat was not obviously affected by age when exposed, duration of exposure, or interval from exposure to testing. The practical implications of these results are discussed.

Early feeding experience and subsequent acceptance of feed by sheep - Keogh RG; Lynch JJ (Proceedings of the New Zealand Society of Animal Production, 1982)
The effects of an extra 'flush' of pasture around mating v recommended pasture allowance levels for beef cows after calving through mating were compared in 1979 and 1980 on cows which had been fed to maintain live weight from 8 weeks prior to and up to calving. Cow live weight after calving was positively associated with increasing feed levels although the differences were small to non-significant by weaning. There were no reproductive responses to feeding better than the allowance of 10 kg DM/cow/d from calving to mating and 16 kg DM/cow/d thereafter to weaning. Cows fed 16 kg Dm/cow/d had a higher pregnancy rate (100 v 90%) than those fed 12 kg DM from calving to mating regardless of flushing treatment in 1979.; More reliable reductions in interval to first oestrus can probably be achieved by delaying calving date. Treatment had no effect on calf weight at weaning.

The effect of clean pasture and anthelmintic frequency on growth rates of lambs on irrigated pasture - Brief Communication - McAnulty RW; Clark VR; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

The effect of early nutrition and hogget oestrus on subsequent reproduction - Moore RW; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1982)
The performance of ~400 Waihora Romney x Romney (W x R) F1 ewes born in both 1977 and 1978, and ~150 W x R B1 ewes born in both 1979 and 1980, was compared with that of similar numbers of contemporary commercial Romney (R) ewes. At hogget shearing W x R ewes were generally heavier (range minus 0.2 to plus 3.9 kg) than R ewes, with fleece weights differing by minus 0.15 to plus 0.26 kg. As two-tooths W x R ewes were 1.0 to 2.9 kg heavier than heavier than R ewes, with 7 to 12 more ovulations per 100 ewes and 1 to 5% fewer lamb deaths, producing 10 to 15% more lambs tailed per ewe joined. More W x R wether lambs were drafted fat than R wether lambs (1979/80 - 77 v 60%; 1980/1 - 98% v 86%).

Effect of ewe ovulation rate and uterine efficiency on breed and strain variation in litter size - Meyer HH; Clarke JN (Proceedings of the New Zealand Society of Animal Production, 1982)
Two experiments investigated the relationship between growth rate, hogget oestrus and subsequent reproduction. In Experiment 1 there were increases in the proportion of two-tooth ewes ovulating multiples due to high plane rearing from late December to mid July or the presence of hogget oestrus, after the correction of two-tooth pre-mating live weight. None of the four-tooth lambing differences due to rearing or hogget oestrus was significant after correction for two-tooth pre-mating live weight. There were no significant differences due to any factor at the six-tooth lambing. In Experiment 2 there was an increase in the proportion of two-tooth ewes twinning due to the presence of hogget oestrus after correction for two-tooth pre-mating weight. There were significant effects of hogget oestrus on four-tooth twinning rates, before but not after, correction for two-tooth pre-mating live weight. There were no significant effects on twinning at the six-tooth lambing.

The effect of Mefluidide on pasture and animal performance - Goold GJ; Jagusch KT; Farquhar P; MacLean KS (Proceedings of the New Zealand Society of Animal Production, 1982)
With high quality herbage from irrigated Nui ryegrass and Huia white clover pastures, supplemented with Matua prairie grass pasture, realised herbage allowances were considerably lower than current recommendations. Allowances were calculated from herbage on offer in a 10-paddock rotational grazed system, with no adjustment being made for herbage grown during the grazing period, and with grazing always to a residue of less than 300 kg DM/ha. An allowance of 1.7 kg DM/ewe/d at flushing provided for a live-weight gain of 3.3 kg over a 6 week period, an allowance of 2.35 kg DM/ewe/d during 90 days lactation supported twin lambs at a growth rate of 230 g/d; an allowance of 1.32 kg DM/d for weaned lambs supported a growth rate of 129 g/d during summer. These results were achieved in self-contained farmlets, with annual herbage production of 14 500 kg DM/ha, stocked with high fertility Coopworth ewes at 22/ha, and calculated to yield 670 kg lamb meat/ha (193% lambs surviving to sale at 33.0 kg live weight). Feed efficiency in this system reflects full utilisation of available herbage, thus never allowing dead material or seed heads to build up in the pasture.

Effects of castrating and surgically dehorning male Drysdale and Tukidale lambs on the efficacy of mechanical head skinning - Sumner RMW; Longdill GR (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

Effects of chewing during eating on particle size reduction and subsequent fermentation in sheep - Ulyatt MJ; Reid CSW; Carr DH (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

The effects of drenching regimen and pasture larval contamination on gastrointestinal parasitism of lambs - Thompson KF; Risk WH; Mason PC; Crosbie S (Proceedings of the New Zealand Society of Animal Production, 1982)
The stimulation of oestrus in ewes early in the breeding season has been known for a number of years but only recently has there been a full understanding of the changes which occur in the ewe. Recent work indicates that only 17 to 21 days isolation from rams is needed to sensitise ewes to the ram. Within 10 minutes of introducing rams, the luteinising hormone (LH) levels increase in the ewe. This can result in a preovulatory LH surge 27 to 35 hours later and a silent ovulation within 54 to 72 hours in anovular ewes. However, 43 to 59% of ewes have a premature regression of the corpus luteum (CL) and a second silent ovulation occurs 4 to 6 days later. This leads to flocks have peaks of first oestrus around days 18 and 24 after ram introduction. Injection of progesterone at ram introduction prevents premature regression of the CL and first oestrus is synchronised over days 19 to 21 after ram introduction. The percentage of multiple ovulations is higher at the silent ovulation than at the first oestrus or in spontaneously ovulating flock mates. Priming with progestagens for 12 to 16 days can induce oestrus at the first ovulation after ram introduction and still maintain the increased proportion of multiple ovulations. The ram effect is due to pheromones which are present in the ram's wool and wax. The buck is as effective as the ram at stimulating ewes and fatty acid pheromones isolated from the buck are also effective at stimulating ewes.

Effects of season and pasture allowance on the wool growth of Romney ewes - Hawker H; Crosbie SF; Thompson KF (Proceedings of the New Zealand Society of Animal Production, 1982)
The minimal drenching recommendations for lambs of the N.Z. Society of Animal Production Study Group (2 or 3 drenches) were compared with 5 and 12 fortnightly drench regimens on safe (low larval count) and contaminated (high larval count) pastures. Lambs grazing safe pastures had lower (P<0.05) gastrointestinal worm burdens than lambs grazing contaminated pastures, and increased drenching frequency significantly reduced (P<0.01) the average faecal egg count. The minimal drenching regimen did not adequately control parasitism in lambs. Increasing the number of drenches improved parasite control and increased wool and live-weight production.

Evaluation of dam breeds and crosses for export lamb production - Clarke JN; Atkins KD; Geenty KG; Johnson DL; Hickey SM; Wilson JA (Proceedings of the New Zealand Society of Animal Production, 1982)
The effects of castrating and surgically dehorning male Drysdale and Tukidale lambs at birth or docking on subsequent horn growth were investigated in 3 lamb crops at Whatawhata Hill Country Research Station. Castration was more effective than dehorning in reducing subsequent horn growth. A combination of castration at birth and dehorning at docking was the most effective way to treat lambs to reduce horn growth. Excision of germative tissue around the base of the horn following dehorning increased the effectiveness of dehorning. Attainment of meat inspection standards for horned breeds is more dependent on the "trimmers" on the slaughter chain than the time of dehorning.

An evaluation of the fat-depth indicator on carcasses of pigs, cattle and sheep - Adam JL; Bass JJ; Kirton AH (Proceedings of the New Zealand Society of Animal Production, 1982)
Results from recent diallel crossbreeding experiments are used to illustrate the range in average genetic merit for meat and wool production available for utilisation in our present breed resources by crossbreeding. Performance of reciprocal first crosses suggests in addition considerable opportunity for exploitation of hybrid vigour. Breed differences are considerably reduced when production is expressed relative to ewe body size, although first-generation crosses remain superior to purebreds on this basis.

Factors controlling fat deposition in meat animals - Wood JD (Proceedings of the New Zealand Society of Animal Production, 1982)
Depth of subcutaneous fat plus skin was measured by Fat Depth Indicator and Introscope on 95 'backed down' hot carcasses from entire males and gilts slaughtered at 70 and 90 kg live weight. Measurements were taken 4 and 6.5 cm lateral to dorsal midline immediately posterior to the last rib. Both probes predicted percentage fat with similar accuracy at the 4 cm site (rsd 2.4%), but at 6.5 cm the Introscope was slightly the more accurate (rsd 2.3%). Allowing for different sex intercepts improved the accuracy of predictions. Accuracy of predicting corresponding fat depths on the chilled carcass varied with probe and site. Linear regression relationships of Introscope of Fat-Depth Indicator fat depths gave residual standard deviations of 1.5 mm and 1.4 mm at the 4 and 6.5 cm sites respectively.

Fertility of inactivated bovine sperm - Shannon P; Curson B; Pitt CJ (Proceedings of the New Zealand Society of Animal Production, 1982)
A semen washing technique employing Ficoll density gradient centrifugation was used to separate ram spermatozoa and seminal plasma. While this technique caused a loss of spermatozoan motility, it was shown by CA2+ flux measurements that these immotile ram spermatozoa still had intact plasma membranes. Furthermore, these immotile spermatozoa were shown to be resistant to cold-shock, a treatment which normally disrupts the sperm plasma membrane. Spermatozoa were shown to be resistant to cold-shock, a treatment which normally disrupts the sperm plasma membrane. Spermatozoan motility was restored by suspending the immotile spermatozoa in diluents containing egg yolk or phospholipids. Ficoll washing appeared to exert its effect on the sperm plasma membrane by an alteration in the membrane lipid components.

Fertility of inactivated ram sperm - Tervit HR; James RW; Shannon P; Tillot M (Proceedings of the New Zealand Society of Animal Production, 1982)
With very few exceptions, consumers are becoming more discerning in their meat buying habits. This relates to such aspects as attractiveness of presentation, price, ease and quickness of preparation and cooking, degree of waste and fat content. The impact of these factors on consumption of red meat and red meat exports from New Zealand are examined with particular reference to response required from producers if they are to contribute effectively to maintain New Zealand's status as a premier export meat nation.

Flushing responses of well and poorly reared two-tooth ewes - Smeaton DC; Webby RW; Hockey H-UP; Wadams TK (Proceedings of the New Zealand Society of Animal Production, 1982)
The effects on two-tooth reproduction of 3 times of shearing relative to joining either in early March or early April were investigated. Ewes were shorn either 4 or 2 weeks before joining or remained unshorn throughout. Ewe fertility was increased by shearing 4 weeks before joining compared with the other shearing treatments. Joining ewes in April increased fertility. It is concluded that ewes should be shorn at least 4 weeks before joining and joined in April rather than March if lamb production is to be maximised.

High animal production from low herbage allowance - Fraser TJ (Proceedings of the New Zealand Society of Animal Production, 1982)
Wool growth responses of Romney ewes to increasing pasture allowance in the autumn (pre-joining), early winter (mid pregnancy) and spring (lactation) were examined. Live weight gain and wool growth increased curvilinearly with allowance. Wool growth responses were greater in autumn than winter, with spring intermediate. The maximum difference in clean fleece weight between extremes of pasture allowance was 0.41 to 0.12 kg for autumn, 0.12 kg for winter and 0.15 kg for spring. Changes in live-weight gain were associated with greater changes in wool growth in autumn than in winter or spring.

Induction of cyclical ovarian activity in seasonally anoestrous Romney ewes: studies with exogenous GnRH or LH - McNatty KP; Ball K; Hudson N; Gibb M; Thurley DC (Proceedings of the New Zealand Society of Animal Production, 1982)
Groups of high and low fecundity Booroola x Romney (B x R) and Romney (R) two-tooth ewes grazed a pasture containing 85% 'Grasslands Pawera' red clover for 10 days; similar groups of ewes grazed ryegrass- white clover control pastures. Oestrus and ovulation were synchronised in all ewes to occur during the last 5 days of grazing. Pawera leaf material contained 0.7% formononetin and the pasture was highly oestrogenic to sheep (>40

The influence of an extra flush of pasture before and during mating on the performance of beef cows on hill country - Smeaton DC; Wadams TK; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1982)
Two experiments involving 715 suckling beef cows were conducted to determine the effects of oestrogen treatment at the time of PRID insertion on the synchronisation of oestrus and conception rate to timed AI. Experiment 1 examined the route of administration and dose level of oestrogen while Experiment 2 studied the effect of oestrogen treatment at PRID insertion and/or an injection of prostaglandin at the time of PRID removal. Treatment with oestrogen resulted in an 18% improvement in synchrony and a 9% increase in conception rate. A dose level of oestrogen 4 times that given by intramuscular injection was required to achieve similar results when it was administered via a gelatine capsule attached to the PRID.

Influence of feeding post-lambing on ewe and lamb performance at grazing - Rattray PV; Jagusch KT; Duganzich DM; MacLean KS; Lynch RJ (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

Influence of herbage allowance on diet quality in lactation ewes - Geenty KG; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1982)
Urinary magnesium concentrations in dairy cows follow a distinct seasonal pattern, being high during the summer and lowest during August and September, coinciding with the period when the incidence of hypomagnesaemia is at its greatest. During this critical period mean urinary Mg concentrations (Y, mg/mg creatinine) measured weekly were related to mean plasma Mg concentrations (X, mM) by expression in Y= - 7.5 + 6.2X (R

Level of nutrition of the ewe and lamb survival - Johnson DL; Clarke JN; MacLean KS; Cox EH; Amyes NC; Rattray PV (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

Modification of antler growth in red deer stags by use of synthetic progestogen - Muir PD; Barrell GK; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1982)
No abstract supplied

New Zealand crossbred wool: aspects of its production uses and prospects - Wickham GA (Proceedings of the New Zealand Society of Animal Production, 1982)
No Abstract Supplied

New Zealand export carcass grades of lamb, mutton and beef: past, present and probable - Barton RA (Proceedings of the New Zealand Society of Animal Production, 1982)
The carcass weight, composition and meat quality of entire rams, Kelly and Russian castrates, wethers and ewes under 6 months old were compared. Wether lamb carcasses averaged 0.6 kg heavier than those of the ewes and the Russian (0.4 kg), Kely (0.6 kg) and ram (0.8 kg) carcasses were heavier than those of the wethers slaughtered at the same mean age. The ram and partial castrates were less fat than the wethers (2.4 to 3.3%) which in turn were 2.7% less fat than the ewes. There were no practical differences in percentage carcass cuts between the rams, partial castrates or castrates. A consumer taste panel in which 48 participating families cooked and tasted a ram and wether leg roast detected no difference between the two types of meat.

Oestrogen and the PRID - Smith JF; McGowan LT (Proceedings of the New Zealand Society of Animal Production, 1982)
Ram sperm inactivated by centrifuging through a Ficoll solution were stored for 3 days at room temperature. A high proportion (80%) of the perm was motile after reactivation with a milk diluent but compared to fresh diluted semen, the sperm gave a low pregnancy rate (6% v 60%).

Ovulation and oestrous responses of high and low fecundity ewes to ingestion of isoflavone-rich pasture - Kelly RW; Shackell GH (Proceedings of the New Zealand Society of Animal Production, 1982)
Well or poorly reared ewes were differentially fed at 1 of 5 pasture allowances for 6 weeks prior to a synchronised mating. Rearing class and flushing treatment significantly affected ovulation rate. The well and poorly reared ewes had mean multiple ovulation rates per ewe cycling of 39 and 19% respectively. Fitting pre-flushing and joining weights as covariates removed rearing and differential feeding effects on those rates. Extrapolation of the data suggests that poorly-reared ewes would ovulate similarly to well reared ewes at similar mating weights. Facial eczema depressed live-weight gain and had a further detrimental effect on the probability of ewes ovulating.

Ovulation rates in Marshall Romney and Romney ewes: effects of body size and condition score - Knight TW; Hockey H-UP (Proceedings of the New Zealand Society of Animal Production, 1982)
Three lines differing markedly in reproductive performance as a result of long-term selection for litter size were compared for ovulation rates and uterine efficiency. Genetic differences in litter size were found to be due to genetic changes in ovulation rate with no evidence of altered uterine efficiency. Three additional lines also showed variation in litter size to be due to variation in ovulation rate rather than differences in uterine efficiency.

Prevention of bark chewing of pine trees by cattle: the effectiveness of repellents - Marnane NJ; Matthews LR; Kilgour R; Hawke M (Proceedings of the New Zealand Society of Animal Production, 1982)
Behaviour patterns which were relevant to parturition and formation of the cow-calf bond were studied and where possible related to calf survival. The relationship of maternal experience (i.e. primigravid v multigravid) to these behaviours was also studied. It was possible to predict the order in which the cows calved and the time of calving. Social isolation, localisation and ingestion of the placenta and associated fluids were found to influence calf survival. Maternal experience was directly related to the occurrence of these behaviours.

The productive performance of Waihora Romney cross hogget and two-tooth ewes and commercial Romneys - Johnston MT; Kelly RW; Webb RR (Proceedings of the New Zealand Society of Animal Production, 1982)
The basic aim of selection in flocks in the 150 to 200% lamb drop range remains unchanged, namely to breed sheep of sound physical type and with the genetic potential to give maximum net profits per hectare from sales of meat and wool. However at these fertility levels the main thrust of selection moves off fertility due to the doubtful benefit of large numbers of triplets under commercial farm conditions. More emphasis can profitably be placed on milking ability as expressed by weaning weight. This has major implications in ensuring quick seasonal disposal of lambs to reduce the pressure on stocking rate brought about by high fertility. Also fleece weight gains in importance as increases in wool production do not involve increased stocking rate. In high fertility flocks health and behaviour traits such as free lambing, mothering ability and resistance to foot problems are of even greater importance. Overall, a very important factor to be considered in future selection in high fertility flocks is that per head gains in production be made while holding ewe body weights, i.e. an emphasis on efficiency for best per hectare results.

Productivity of Booroola-Merino cross ewes grazing improved tussock grassland - Bray AR; Allison AJ (Proceedings of the New Zealand Society of Animal Production, 1982)
Permanent incisor eruption patterns varied widely for 13 genotypes of ewes examined. Progeny of Ruakura High Fertility Romney sires displayed markedly earlier teeth eruption than other strains while Southdowns were later than any other genotype in the study. The wide variation observed both between and within breed types questions the reliability of dentition for ageing individual animals for sale.

The profitability of farming red deer in New Zealand - Floyd PG (Proceedings of the New Zealand Society of Animal Production, 1982)
Four scrub-pasture associations containing different proportions of grass, white clover and gorse were developed by grazing with different ratios of goats and sheep. The ratios were: 100% goats (Goat 100), 66% goats and 34% sheep (Goat 66), 33% goats and 67% sheep (Goat 33) and 100% sheep (Sheep 100). These associations were then grazed by oesophageally fistulated goats and sheep in each season for 2 years. Grass was the principal feed of sheep in all associations (77% of diet) and of goats (62%). Sheep ate white clover in proportion to its presence in the sward (14%) whereas it was rejected by goats (2%). Gorse was a preferred feed for goats (20%) but the principal feed only when gorse >10% of the association; sheep ate very little gorse (0.1%). Dietary overlap between goats and sheep was greatest on the Goat 66 association (0.89), which was grass dominant. It was less on the ?Goat 100 (0.69) where sheep ate more legume, and the Goat 33 (0.66) where goats ate more gorse. On the Sheep 100 association it was the lowest (0.12) because goats ate mainly gorse and sheep mainly grass and white clover.

Progeny test of selected lean and fat rams - Fennessy PF; Greer GJ; Bass JJ (Proceedings of the New Zealand Society of Animal Production, 1982)
Separate trials were conducted to investigate the effects of a synthetic progestagen - medroxyprogesterone acetate (MPA) - on red deer stags at 2 different stages of the antler growth cycle. MPA treatment of 2 stags from the time of harvest of 'A-grade' velvet stimulated the growth of additional sets of antlers in each case. This treatment also reduced blood testosterone levels and prevented the seasonal increase in testicular size. Alternatively, MPA treatment applied to 6 stages during their hard antler phase (winter) caused premature casting of the antler buttons in all animals. These findings indicate a possible role of MPA or similar compounds for the artificial manipulation of antler growth under farming conditions.

Recent and potential changes in meat processing and their implications for producers - Chrystall BB (Proceedings of the New Zealand Society of Animal Production, 1982)
The paper takes the view that meat sales are likely to benefit from a reduction in average fat levels, particularly in lamb. Total fat content is controlled by the mature size of the breed or strain and by the stage of maturity that has been reached. The balance between appetite (energy in) and maintenance requirement (energy lost) seems less important, although there are examples of lean genotypes with low appetites. The partitioning of total fat between carcass (particularly subcutaneous) and abdominal (particularly perirenal) sites is not influenced by mature size but rather by breed itself, especially in cattle. The reason may lie in intrinsic metabolic differences between subcutaneous and abdominal fat tissues. The number of fat cells in subcutaneous fat, but perhaps not in other fat deposits, increases as total fatness increases. Attempts to reduce eventual fat content by reducing the number of cells through underfeeding in early life have not been successful. Hormonal metabolism can be altered by injecting or implanting active constituents and sex hormone implants are presently available in some countries which aim to confer on females or castrated males the advantages (in terms of low fat and high lean deposition) of the entire male. However their effectiveness in reducing fat content is less than in increasing overall growth. Immunological techniques of growth control are being developed which leave no residues in meat and it is likely that the future will see increasing use of these and other approaches as farmers strive to meet consumers' requirements for lean meat at even lower production costs.

Relationships of carcass conformation of cattle and sheep with carcass composition - Bass JJ; Johnson DL; Woods EG; Moore RW (Proceedings of the New Zealand Society of Animal Production, 1982)
Hemicastrates and steers were slaughtered at similar carcass weights at 14, 18 and 22 months of age for the assessment of factors associated with tenderness difference in representative forequarter muscles. Objective tests indicated that hemicastrate meat was tougher than that from steers at 22 months of age only. Heat labile collagen content was the major parameter associated with tenderness in M. longissimus; in both M. splenus and M. triceps brachii it was sarcomere length.

Reproductive performance of beef cows following temporary removal of calves - Tervit HR; Smith JF; Goold PG; Jones KR; Vandien JJD (Proceedings of the New Zealand Society of Animal Production, 1982)
Bovine sperm was inactivated by centrifuging twice through a 7% Ficoll solution. The inactivated sperm could be reactivated for periods up to 10 days with B.S.A., egg yolk, seminal plasma and milk. To test the effect of inactivation on fertility semen was either (1) immediately diluted in Caprogen + 5% egg yolk; or (2) twice centrifuged and then diluted as above; or (3) twice centrifuged, stored in an inactivated condition for 60 h and then diluted as above. Cows were inseminated 72 h after collection of semen. Fertility following insemination was (1) 74.3%; (2) 72.5%; (3) 54.2%. Storage of sperm in the inactivated condition reduced fertility (P<0.01).

Selection priorities in high-fertility sheep flocks - Black PD (Proceedings of the New Zealand Society of Animal Production, 1982)
Reducing "idling" time of cattle, redirecting responses away from bark chewing, or applying a "repellent" substance could be potential management tools for controlling damage to pine trees. Egg- powder, copper carbonate, thiram, cattle dung and scatole were compared as repellents. The dung treatment was the most effective in preventing bark chewing. Egg-treated trees were licked and not chewed. As a readily available material, cattle dung has a potential use in the control of bark chewing.

Shearing and time of joining effects on reproduction in two- tooth ewes - McMillan WH; Knight TW (Proceedings of the New Zealand Society of Animal Production, 1982)
Local Merino, 1/4 local Merino and 1/2 local Merino ewes were grazed on oversown and top-dressed tussock grassland. When ranked for lamb and wool productivity at 2 and 3 years of age both the Booroola crosses were superior to the Merino. Satisfactory lamb weights and ewe fleece weights were obtained at lambing percentages above those normally obtained on this class of land.

Sheep distribution and herbage utilisation after oversowing and top-dressing part of a high country summer range - Abrahamson M; O'Connor KF; Harris PS (Proceedings of the New Zealand Society of Animal Production, 1982)
Calves were removed for 48 hours from cows at 2 localities in 1978. Removal shortened the interval from calving to first oestrus at both localities. It shortened the interval from calving to conception and advanced the 1979 calving date at the locality which had the better level of nutrition. Weaning weights of the removed calves were depressed at both localities. The intervals from calving to first oestrus were affected at both localities by dam age and breed, 1978 calving date and condition score at removal.

The shelter requirements of the new-born lamb - Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1982)
No Abstract Supplied

Tooth eruption patterns in New Zealand sheep breeds - Aitken WM; Meyer HH (Proceedings of the New Zealand Society of Animal Production, 1982)
Daytime grazing activity of 16 high (BI = 123) and 16 low breeding index (BI = 105) cows was observed during 3, 7-day periods in early, mid and late lactation. There were no differences in grazing, lying or standing times between high and low BI cows during early or mid lactation. High BI cows grazed longer during late lactation. There were no differences in daytime drinking frequency. Individual cow milking times were recorded during 5, 2-day (4 milkings) periods at bimonthly intervals. High BI cows consistently outproduced low BI cows throughout lactation by 3 kg of milk/d. High BI cows had shorter milking times in early lactation but these differences diminished as lactation progressed. No relationships between milking entrance order or milking temperament and breeding index were found.

Trends in meat market requirements: implications for producers - Frazer AE (Proceedings of the New Zealand Society of Animal Production, 1982)
Some information of the first exports of frozen meat from New Zealand is given partly as a background to the development of export carcass grade standards. Investigations that have examined the physical and/or chemical composition of carcasses according to grade are reviewed as are examples of research studies that have used carcass grade as one of the traits considered. On the basis of very limited evidence, it is concluded that selection of meat animals for carcass grade is unwarranted but that improvement in carcass quality through breeding should take into account the need to reduce fat content and increase the depth of muscling both of which are, or should be, closely related to carcass grade. It is emphasised that those who produce meat animals of high carcass merit should be properly rewarded for their effort. A brief speculation into the future of carcass grades is made, but whether grading will be replaced by a carcass classification scheme or some other procedure that is automatic, quick and pertinent remains in the future.

Urinary magnesium - an indicator of magnesium status/intake? - Towers NR (Proceedings of the New Zealand Society of Animal Production, 1982)
Animal production was measured in a grazing experiment on North Island hill country from 1975 to 1981. Two grazing managements, set stocked and rotationally grazed sheep, were compared at 'maintenance' fertiliser (LF) and 'high' fertiliser (HF). Stocking rate increased from 6.3 to 11.3 ewes/ha and 7.3 to 15.1 ewes/ha on LF and HF respectively with no decline in per animal production. HF gave 30% more wool/ha and 36% more weaned lamb weight/ha as a results of the increased stocking rate. There were no fertiliser x management interactions. Management effects were inconclusive. At lower stocking rates set stocking increased ewe mating live weight, increased lambing percentage, increased lamb weaning live weight and hence increased weaned lamb weight/ha. However, at the highest stocking rate rotationally grazed ewes lost less live weight in late pregnancy and had higher lamb weight/ha.

Agricultural growth - A possibility or a fantasy? - Rattray PV (Proceedings of the New Zealand Society of Animal Production, 1981)

Aspects of energy metabolism of Jersey cows differing in breeding index - Trigg TE; Parr CW (Proceedings of the New Zealand Society of Animal Production, 1981)

Breeding for facial eczema resistance - A progress report - Campbell AG; Meyer HH; Henderson HV; Wesselink C (Proceedings of the New Zealand Society of Animal Production, 1981)

The case of induced early parturition in New Zealand dairy cattle - Brief Communication - Moller K; MacDiarmid SC (Proceedings of the New Zealand Society of Animal Production, 1981)

A comparison of lucerne and grass-clover pastures for dairying in South Taranaki - Brief Communication - Thomson NA; Lagan JF (Proceedings of the New Zealand Society of Animal Production, 1981)

Early predictors of ewe fertility - Meyer HH (Proceedings of the New Zealand Society of Animal Production, 1981)

The effect of a low rate of lime on North Island hill country pasture and animal production and the economics of use - O'Connor MB; Foskett HR; Smith A (Proceedings of the New Zealand Society of Animal Production, 1981)

The effect of daily infection with O. circumcincta larvae on the performance of pregnant and lactating sheep - Leyva V; Henderson AE; Sykes AR (Proceedings of the New Zealand Society of Animal Production, 1981)

Effect of grazing management on hogget fleece characteristics - Sumner RMW; During C; Webby RW (Proceedings of the New Zealand Society of Animal Production, 1981)

The effect of growth implants on cattle and sheep production - Brief Communication - McKenzie JR (Proceedings of the New Zealand Society of Animal Production, 1981)

Effect of mating Romney ewe hoggets on lifetime production - Preliminary results - Baker RL; Clarke JN; Diprose GD (Proceedings of the New Zealand Society of Animal Production, 1981)

Effect of nutrition and mating management on calving patterns - McGowan AA (Proceedings of the New Zealand Society of Animal Production, 1981)