Live-weight gains were recorded for 459 intact male (bull) calves kept in 17 groups on three farms. The correlation coefficient between weight gained during the first 110 to 130 days of life and that gained during the subsequent period until slaughter was r = 0·53 (n = 459; P < 0·001). It is suggested that with bulls, nutritional and other factors which increase live-weight gain during the rearing period to about 4 mo of age may have a positive effect on subsequent performance to slaughter.

The recent war has occasioned even greater changes in agricultural production than followed World War I. Lack of man power and draught power reduced the area of cultivation : lack of fertiliser and manure reduced the yields per acre: lack of feeding stuffs reduced livestock numbers and the output of meat, milk and eggs. This was precipitated at a time in history when it was already becoming evident that, despite improvement in agricultural technique, the output of food per acre over the world was rising comparatively little.

The pre-war agricultural problem, never clearly seen until recent years, of expanding production to meet the requirements of an increasing population, has become gravely accentuated by the additional problem of agricultural recovery following the second world war.

New Zealand is primarily an agricultural country. Sixty per cent of all its production, including nearly 100% of its exports, comes from farms and is produced by only 17% of the total labour force. Within the agricultural industry sheep farming is dominant. Wool provides between one-third and one-half of the total exports and lamb and mutton about one-sixth. Over 90% of the wool and lamb produced and about 50% of the mutton is exported.

The prominent place that wool occupies in New Zealand’s farming strikes any visitor from Britain. The wool cheque naturally exceeds the income from other sources on the sheep stations of the Southern Alps where Merino sheep are grazed, but on lower hill farms selling cast-for-age or surplus two-tooth ewes to fat-lamb breeding farms and store lambs to hogget fatteners the wool cheque is still usually more than half the income.

An experiment was conducted to examine the effect of ammonia treatment or soya-bean meal supplementation on rumen and lower tract digestion and urinary purine-derivative excretion in sheep given barley straw-based diets. Four wethers each fitted with simple rumen and duodenal cannulae were randomly allocated to four diets in a 4×4 Latin-square design. The diets were, untreated barley straw + molasses meal (diet 1), ammonia-treated barley straw + molasses meal (diet 2), untreated barley straw + soya-bean meal + molasses meal (diet 3) and ammonia-treated barley straw + soya-bean meal + molasses meal (diet 4). Dry-matter (DM) intake, total tract neutral- and acid-detergent fibre apparent digestibility and faecal nitrogen (N) output were higher for diets 2 and 4. Microbial protein yield, determined from total urinary purine-derivative excretion, was also high in sheep on diets 2 and 4. However, supplementation with soya-bean meal in diet 4 reduced DM and fibre digestion but increased intake and microbial synthesis. Despite the lower microbial protein synthesis for diet 3, total tract N digestion was high for the diet, an indication of higher nutrient absorption in the lower tract. The above results indicated that there was a substantial increase in rumen microbial N yield from ammoniated straw-based diets. However, not all the N was made available to the animals. Some of the microbial N absorbed in the lower tract may have been overestimated by the use of the purine derivative-microbial N evaluation method. On the other hand, when protein supplements were given the amount of microbial protein available to the ruminant through absorption in the lower tract may have been underestimated by urinary purine derivatives.

Comparative slaughter was used to assess the body composition of Shorthorn-Hereford (SH), Africander cross (A×), Brahman cross (B×), and late castrated Brahman cross (B×(late)) steers of the F, generation with respect to their yield of carcass, gross carcass composition and offal composition. Animals were slaughtered at pre-determined weights of 315, 355, 399, 449 and 505 kg.

The B× animals had the highest carcass yield (expressed either as dressed carcass weight at the same fasted body weight or at the same empty body weight), while the A×, B×(late) and SH animals had similar carcass yield. Within a breed, rate of growth affected carcass yield, with faster growing animals having the lower carcass yield, particularly with respect to fasted body weight.

The breeds were different in carcass composition but this was dependent on both size and growth rate. Brahman cross animals had a lower proportion of bone than A× and SH animals, particularly at the higher body weights. Faster growing animals tended to contain more muscle and bone and less fat, with the exception of the SH animals.

The breeds were also significantly different in the composition of the offal components. A× were notable for high head weights and low tail weights, B× having high blood weights and low total gut tissue weights, and Bx(late) having high hide weights and low abdominal fat weights.

Rate of growth had some effect on offal composition, the general trend being that the faster growing animals were characterized by a lower proportion of heart, blood and pancreas. However there was also evidence that the rate of growth differentially affected the offal composition with respect to breeds. This effect mainly arose because the faster growing B×(late) animals had lower weights of abdominal fat. Within the other breeds, the opposite trend was observed.

Sixty-nine rams of three crossing-ram breeds were mated on 11 farms over 3 years to produce crossbred ewes for a large field trial. Scottish Blackface and Welsh Mountain ewes mated to Bluefaced Leicester rams had larger litters at weaning than those mated to Border Leicester and the Animal Breeding Research Organisation's Damline rams. The crossbred Bluefaced Leicester lambs were heavier than the other crossbred lambs at both birth and weaning.

Feeding big round-bales in round-bale feeders are known to reduce labor and costs. However, one disadvantage is the high feed wastage. The aim of these experiments was therefore to investigate the effect of feeder design, type of roughage and size of round-bales on feed wastage in sheep. Four round-bale feeders (Diagonal Rail Sheep Circular Feeder (RD), Knarrhult Flexible Round-Bale Feeder (KR), Telemark Round-Bale Feeder (TR) and Standard Sheep Circular Ring Feeder (RV)) were distributed into four identical experimental pens and used in both experiments. In Experiment 1, two types of roughages were used; Roughage 1: low-quality, grass silage harvested at late stage of maturity with dry matter (DM) content of 560 g/kg and Roughage 2: high-quality, hay harvested at an early stage of maturity with DM content of 738 g/kg. In Experiment 2, ewes were offered hay harvested at the late stage of maturity with DM content of 766 g/kg as half and whole round-bales. In both experiments, four groups of 10 ewes of the Norwegian White breed were rotated between the experimental pens and each treatment lasted for 4 days. Feed wastage (roughage on the ground surrounding the feeder) was collected daily. The amount of feed wastage was generally high. The type of roughage (Experiment 1) had a large effect on feed wastage (P < 0.001), where Roughage 1 had a mean feed wastage of 1.88 kg DM/day per ewe and Roughage 2 had 0.48 kg DM/day per ewe. When Roughage 1 was provided, it was evident that the ewes pulled out the long fibrous stems of the feeders and left them as wastage while selecting the leaves. This was not the case for Roughage 2. When feeding half round-bales (Experiment 2), the mean feed wastage was 1.50 kg DM/day per ewe compared to 2.88 kg DM/day per ewe when feeding whole round-bales (P < 0.001). This is probably due to the ewes spending more time eating with their heads inside the feeder when fed half round-bales (P < 0.001) and thus dropped more of the potential wastage inside the feeder. Less feed inside the feeder may also be the reason that feed wastage decreased gradually from Day 1 to Day 4 in both experiments (P < 0.001). Feeder design also had a significant impact on feed wastage (P < 0.001). We conclude that providing early harvested roughage and feeding half round-bales significantly reduced feed wastage.

Previous experiments (Osafo, Owen, Said, Gill & McAllan, 1992), investigated the possibility of using low-input technology to improve intake of sorghum stover in sheep and cattle. Physical form of stover influenced intake differently in sheep and cattle; chopping stover increased intake in sheep but decreased intake in cattle.

In an earlier experiment in the same research project, Aboud, Owen, Reed, & McAllan (1990) offered sheep, chopped stovers from bird-resistant (BR) and non bird-resistant (NBR) sorghum. It was hypothesised that intake of BR stover would be lower on account of its higher content of anti-nutritional, polyphenolic compounds. The results were contrary to expectation. The higher leaf:stem in the BR stover was thought to counteract the anti-nutritional factors and account for the higher intake and growth with BR stover. In view of the differences in leaf-plus-sheath:stem ratios between the BR and NBR stovers, the experiment was considered inconclusive. Also the fact that the stovers were supplemented with cottonseed meal may have alleviated any detrimental effect of feeding NBR stover.

Ventilation rates of 0·14, 0·42 and 0·71 m3/min per pig (2·3, 6·9 and 11·5 air changes per hour) were compared at weight ranges from 42 to 65 kg and from 69 to 88 kg and at optimum ambient temperature and at 8°C above optimal. A total of 96 pigs was used, housed so that gases from manure decomposition were present. Growth rate and food conversion were not affected by ventilation rates, but food intake was significantly lower at the lowest ventilation rate compared with the other two rates at the hotter temperature only. The odours and gases at the lowest ventilation rate were such that attendants strongly objected to them.

Vitamin A is a well-known antioxidant and is essential for embryonic development, growth and differentiation. Oxidative stress is involved in the etiology of defective embryo development. The present study evaluated whether the presence of all-trans retinol (0, 1, 2, 5 and 10 μM) in maturation medium or embryo culture medium would enhance the developmental competence of preimplantation buffalo embryos in vitro. In experiment I, cumulus oocytes complex were matured with varying concentrations of all-trans retinol. Treatment with 5 μM all-trans retinol improved the blastocyst formation (P < 0.001) when compared with control and significant increase (P < 0.01) in total cell number was observed in 5 μM group when compared with control. Supplementation of all-trans retinol in embryo culture medium for the entire culture period under 5% O2 and 20% O2 was tested in experiments II and III, respectively. Supplementation of 10 μM all-trans retinol under 5% O2, significantly reduced blastocyst formation and cell numbers. Presence of 5 μM all-trans retinol under 20% O2 enhanced the frequency of blastocyst formation and total cell number (P < 0.001) when compared with control. DNA damage of individual embryos cultured under 20% oxygen concentration was measured by the comet assay. Supplementation of 5 μM all-trans retinol significantly reduced the comet tail (P < 0.001) when compared with control. Supplementation of all-trans retinol in embryo culture medium for first 72 h of the 8-day culture period under 5% O2 was tested in experiment IV. Addition of 5 μM all-trans retinol resulted in significant increase in blastocyst rate and total cell number (P < 0.001) when compared with control. Our results demonstrate that addition of all-trans retinol to maturation or embryo culture medium may enhance the developmental competence of buffalo embryos in vitro by enhancing blastocyst formation rate and total cell number.

This study determined the correlated responses in reproductive performance after five generations of divergent selection for components of efficient lean growth rate in Large White pigs.

Data were collected from five generations of pigs divergently selected for daily food intake (DFI), lean food conversion (LFC), lean growth rate on ad-libitum feeding (LGA) and lean growth rate on restricted or scale feeding (LGS). In each selection group, there were high, low and control lines, each consisting of 10 boars and 20 gilts. Animals were mated at around 9.5 months of age. Pregnant gilts were fed 2.5 kg daily and farrowed sows up to 3.5 kg twice daily of a 160 g/kg DM crude protein and 132 MJ/kg DM digestible energy ration. Animals were farrowed at 414 (s.d. 19.7) days of age, on average. No cross fostering was practised. Piglets were offered creep feed containing 235 g/kg DM crude protein and 160 MJ/kg DM digestible energy from 14 days and were weaned at an average of 35 (s.d. 3) days. Litter traits were measured on 1220 selected Large White gilts, with 13030 piglet birth weights and 9951 weaning weights.

The use of additives such as ractopamine (Rac) in pregnant sows during early-mid pregnancy is an alternative to increase foetal and progeny growth and development. However, Rac supplementation in finishing pigs can lead to behavioural and physiological changes similar to the typical stress responses. The objective of this study was to evaluate the effects of dietary supplementation with Rac in pregnant sows from day 25 to 50 of gestation (pre-hyperplastic stage) on piglet’s vitality, blood parameters, number, diameter and perimeter of muscle fibres in semitendinosus muscle and developmental characteristics of piglets at birth to weaning. Forty-one hybrid sows were divided into three dietary treatments: (1) control diet without Rac (control), (2) addition of 10 mg/kg of Rac (Rac10) and (3) addition of 20 mg/kg of Rac (Rac20). Higher numbers of low-vitality piglets (P<0.05) were observed in Rac-fed sows, regardless of dose, compared with the control group. Very low-density lipoprotein levels were lower in the Rac10 group when compared with the Rac20 group at day 21. Haematocrit was greater, and the mean corpuscular haemoglobin concentration was lower in piglets from Rac-fed sows. No significant statistical differences were detected regarding piglets body weight, average daily gain, blood gasometry, complete blood count and muscle fibre measurements in semitendinosus muscle. The use of Rac in pregnant sows reduced the vitality parameters of piglets but did not improve the performance from birth until weaning and did not negatively influence the haematological parameter and lipid metabolism.

Forty British Friesian male calves were pair-fed creep feeds containing 67% of either cooked potato or cooked maize in the form of a dry coarse meal or finely ground in liquid suspension.

Although dry maize diets were more acceptable than dry potato diets, daily gains were unaffected by either diet composition or drymatter content.

Calves on liquid-fed diets produced faeces of significantly lower dry-matter content.

The inclusion of 60 p.p.m. of 2,4-dichlorophenoxy acetic acid (2,4-D) or of M15† in the diet of lambs had no effect on the concentrations of volatile fatty acids and ammonia in rumen liquor, on the contents of haemoglobin, protein and non-protein nitrogen in blood or on the composition of the blood serum proteins. Over weeks 1 to 6 of experiment, there was a significant increase in live-weight gain in lambs receiving a diet containing M1S but the effect had disappeared at the end of 12 weeks. Inclusion of 2,4-D in the diet had no effect on live-weight gain.

The least squares analysis on birth, weaning, 6-month and yearling weights in Magra lambs showed that years of lambing, age and weight of dam at lambing and sex of lamb significantly affected all the body weights except the age of dam which did not significantly affect 6-month and yearling weights. Adjustment of these weights for significant effect will be necessary in obtaining estimates of genetic and phenotypic parameters.

The concentrations of LH and oestradiol-17β were measured in samples of jugular venous plasma collected frequently during an 8-h period from six acyclic cows between 21 and 27 days post partum. Fluctuations in oestradiol-17β concentrations were detected. Although the mean concentrations of oestradiol were similar whether ovulation occurred within 1 week of sampling or not, the amplitude of the fluctuations in oestradiol concentrations was greater in the three cows which ovulated within 1 week of the period of sampling. Increases in the concentration of LH were frequently followed by increases in the concentrations of oestradiol.

In young pigs, it is common to find individuals which grow appreciably slower than their litter-mates. Such “runts” are an important cause of economic loss in the pig industry. Extreme examples are easily recognisable but an adequate definition of what constitutes a runt is more difficult. It is, however, possible to separate slow growing pigs from the remainder and compare them in a number of ways. During the course of a study involving routine observations on the behaviour and growth of piglets, data were obtained which made it possible to compare slow growing pigs with others. It is the aim of this study to tabulate these differences and to relate them to the weights of piglets at birth.

Forty-two British Friesian castrated male calves of 1 to 3 weeks of age were offered ad libitum unwilted or wilted silage made from the same sward for 21 consecutive weeks. Both silages were supplemented with a cereal and protein concentrate at two restricted levels of intake or with dried grass cobs offered ad libitum. There was little difference i n the chemical composition ofthe two silages except for DM content. Dry-matter intake of wilted silage was slightly but not significantly greater than that of unwilted silage. Differences between silages in daily gain or final live weight were not significant.

An increase in the intake of the cereal and protein concentrate led to a significant decrease (P < 0·001) in silage DM intake and a significant increase (P < 0·001) in daily gain andfinallive weight. Calves offered dried grass as a supplement to silage ate similar quantities of silage DM to calves offered an equal amount of the cereal and protein supplement but gained significantly less (P < 0·001) live weight. When intakes were presented on a unit metabolic live-weight basis, calves ate significantly more (P < 0·001) silage when supplemented with dried grass than calves offered the cereal and protein supplement.

The main factor limiting fecundity in sheep is the low ovulation rate (Hanarahan, 1980). The relationships between body condition, level of nutrition and ovulation rate, and the ability to increase fecundity by flushing ewes prior to mating, are all well established (Gunn, 1983). In upland ewe flocks, flushing is generally attempted by the use of saved autumn pastures. However, the seasonal variation in grass growth often results in the degree of flushing desired not always being possible and leaving the flockmaster seeking a viable option.

The present investigation examined two possible alternative strategies for increasing the fecundity of upland ewes. Improving body condition prior to mating by supplementary feeding was compared with the recently developed technique of increasing ovulation rate by active immunisation against androstenedione (Scaramuzzi, Cox and Hoskinson, 1982).