Three experiments were carried out to investigate the anabolic effects of androstenedione administered at various levels to female and castrated male lambs in one experiment and to entire and castrated male calves in two other experiments. Significant increases in growth were not effected in normally fed animals but a sex × dose level interaction was detected in female lambs. Under normal husbandry conditions androstenedione appears to have little application in meat production.

In an experiment with group-fed cattle from 6 months of age to slaughter at 480 kg live weight two levels of feed intake: 1, ad libitum, 2, 85% of ad libitum amount, were combined with two ratios of concentrate to hay: a, 70: 30; b, 30: 70. In two further treatments, 3a and 3b, the cattle were fed diets a or b at 70% of ad libitum from 6 to 10 months and ad libitum thereafter.

Daily gain during the first 124 days of the experiment was (in grams) 1293, 983, 1097, 846, 992 and 756, and from the 125th day to slaughter 735, 600, 796, 579, 830 and 714, for treatments la, lb, 2a, 2b, 3a and 3b, respectively. The decline in rate of gain from the first period to the second was inversely related to the level of feed intake and to the percentage of concentrates in the ration in the first period.

Daily carcass gain was 582, 393, 532, 350, 531 and 368 g for treatments la, lb, 2a, 2b, 3a and 3b, respectively.

The treatments that were switched over from 70% of ad libitum feed intake in the first period to 100% in the second (3a and 3b), exhibited considerable compensatory growth in the second period, but this was not sufficient to be of economic advantage.

The overall ME requirement per kg of live-weight gain was inversely related to rate of gain. Of the six treatments, 2a (85% of ad libitum, 70% concentrate) was the most efficient (19·8 Mcal/kg live-weight gain).

Animals on the 100% level of feed intake throughout the experiment (treatments la, lb) were significantly fatter than those on the other treatments.

Ninety-nine ewes, 33 from each of the Cyprus fat-tailed, Chios and Awassi breeds, were used to compare the effects of three suckling regimes on lactation. These consisted of weaning the lambs at birth (W0), 2 days (W2) and 35 days (W35). The 35-day, 150-day and total milk yields, as well as lactation length, were measured for each group. The lambs weaned from the ewes at birth and 2 days were reared on ewe-milk replacer. The growth rate of these lambs was compared with that of the lambs being suckled by their dams, before and after weaning.

In all cases the milk yields of the Chios and Awassi breeds of sheep were significantly higher (P<0·01) than those of the Cyprus fat-tailed. Within each breed the 35-day milk yields of the ewes suckling one lamb were significantly higher (P<0·01) than those of the ewes on the W0 or W2 treatments, which themselves did not differ significantly. While the 150-day milk yields of the W35 treatment were significantly higher than those of the W0 or W2 treatments, the differences between suckling regimes in terms of total milk yield and lactation length were not significant. It is concluded that differences in milk yield obtained on different suckling regimes are attributable solely to the length of time that the lambs are suckled by their dams.

Prior to weaning the growth rate of the lambs given the ewe-milk replacer was significantly lower than that of the lambs suckled by their dams. There were no differences in the growth rates of these groups of lambs when both were fattened on a creep feed after weaning.

Two forms of supplement, barley or dried grass pellets (G) were given to weaned lambs, set-stocked at pasture, at three stocking rates (43·5, 60 and 87 per hectare). The supplements were given either from weaning or from the time growth rate fell below a target value. The supplements significantly increased the proportion of lambs reaching the target weight (35 kg) and G was significantly better than barley, but slightly more G was given. The substitution value of supplement for herbage was 0·48 ± 0·12 and there was no difference in this value between barley and G. The proportion of lambs reaching the target slaughter weight was not influenced by whether the supplement was offered at weaning or delayed until lamb growth declined below a target level. Increase in stocking rate depressed the herbage intake and growth rate of the unsupplemented control lambs.

Two feeding trials involving 105 pigs weighing approximately 14·5 kg were carried out to investigate the effects of palm oil, groundnut oil, locally produced lard, and beef tallow at 2·5% and 5% of the diet, on performance characteristics and carcass quality. The pigs were of the Yorkshire and Yorkshire × Landrace crosses, and of both sexes. The 23% protein basal diet had no oil added, and the other eight diets were made from the basal diet by the weight-for-weight substitution of the maize with the 2·5% or 5% levels of the four oil types. The results of the two trials were combined and considered as a 2 × 4 factorial experiment (2 levels and 4 types of oil) with the basal diet serving as the control. Only the pigs in the second trial were slaughtered and their carcasses graded at the average live weight of 57±1 kg. Correlation and regression analyses were made on some performance and carcass characteristics, on the average daily digestible energy intake. Results showed no significant treatment differences in the average daily gains, average daily feed intake, and average daily digestible energy intake, but there were highly significant treatment differences in feed consumed/kg of gain and average digestible energy (DE) consumed/kg of gain (P<0·01). None of the carcass quality parameters showed any significant treatment differences. Both the correlation and the regression coefficients for the average daily gain on DE intake were highly significant for all the oil types and levels, but the relationships were low and non-significant when the feed/gain ratio, average backfat thickness and the average percentage of lean cuts were regressed on the daily DE intake.

In Experiment 1, 24 early-weaned, male lambs were given ad libitum a diet based on either rolled or whole barley, both pelleted through a 7·4 mm die. Growth rates were 360 and 409 g/day, food conversion ratios 2·80 and 2·56 kg dry matter/kg gain, and organic-matter digestibilities 77·8 and 80·4% for the two diets respectively. In Experiment 2, 12 early-weaned, female lambs were given a diet based on either whole barley pelleted through a 7·4 mm die or unprocessed barley. When the diets were given in restricted quantities those containing unprocessed barley were slightly but significantly higher in digestibility. The feeding of unprocessed barley increased the firmness of subcutaneous fat and the contents of the rumen at slaughter, but decreased liver weight.

In Experiment 3,36 early-weaned, female lambs were given ad libitum diets based on either pelleted rolled barley, pelleted whole barley or unprocessed barley. Growth rates were 260, 270 and 264 g/day; food conversion ratios were 3·20, 3·20 and 3·00 kg dry matter/kg gain organic-matter digestibilities were 80·8, 79·3 and 81·0%, rumen pH values were 5·2, 5·2 and 6·1, and liver weights 728, 788 and 673 g, for the three diets respectively. As in Experiment 2, the subcutaneous fat on the cold carcass was firmer and more acceptable to the butcher when whole barley was given.

In two experiments dried grass cobs or concentrate were offered to calves for 20 weeks after weaning. In Experiment 1 the grasses were harvested in the autumn and in Experiment 2 in the spring. Within each experiment three grasses differing in quality and two levels of concentrate were compared.

Dry-matter intake of the dried grasses highest in digestibility was lower than that of medium digestibility grass, and hardness of package, palatability and mould infestation were implicated as possible causal factors.

Live-weight gains by calves were closely correlated with digestible organic matter (DOM) intake. There was no significant difference between spring harvested grasses and concentrate in efficiency of utilization of DOM for live-weight gain but autumn grasses were used less efficiently than concentrate. At similar rates of gain the replacement value (dry-matter basis) of dried grass for concentrate averaged 142: 1.

An experiment was carried out with 64 lambs to determine the digestibility and efficiency of food utilization of barley, maize, oats and wheat when they were offered whole and loose, or roughly ground and pelleted.

Apparent digestibilities of the organic matter (%) for the four cereals in the order given above were 81·1, 84·3, 69·9 and 82·7 for the whole and 77·2, 82·1, 67·5 and 86·6 for the ground and pelleted grains. The corresponding live-weight gains (g/day) were 340, 345, 241 and 303, and 347, 346, 238 and 323. The corresponding conversions of dry matter (kg) to live-weight gain (kg), over the growth period from 15 to 35 kg weight, were 2·75, 2·52, 3·07 and 2·97 and 2·79, 2·62, 3·33 and 2·56.

Changes in the level of aggression in a restricted feeding situation were examined in a herd of goats with a stable dominance hierarchy. It was found that the number of butts occurring (the level of aggression) depended on both the nature and novelty of the various feeds presented. In general the highest number of butts and the lowest consumption were recorded on the first occasion that each feed was presented. The introduction of unfamiliar or highly desirable feeds to livestock may require special precautions if increased aggression is to be avoided.

Dried poultry waste was substituted for soya and fish meals in an intensive beef ration to ascertain if it was a satisfactory alternative source of nitrogen and in an attempt to reduce the cost of production. The experiment was conducted over 3 years in each of which groups of autumn-born British Friesian male castrates were taken from 150 kg live weight to slaughter at 400 kg on various rations. The treatment rations were made isonitrogenous with the control (14·5% crude protein). When the crude protein of the poultry manure was low (24%) it was necessary to include 27·6% in the diet and poor performances resulted. For manures of 30 % crude protein, or when urea was added to equalize the nitrogen content of diets containing up to 17·5% manure, performance was not markedly different from that shown with control diets. There was a considerable saving in the food cost at the prices ruling when the experiment was conducted and it was concluded that the use of dried poultry manure could increase the profitability of intensively produced beef.

Results are reported of an experiment with 60 pigs (12 pigs/treatment) covering the growing period between 22 and 87·5 kg live weight in which the growth-stimulating properties of sodium salicylate were examined either as a single additive or with copper sulphate. The pigs were individually fed a wet diet ‘to appetite’ and the quality of the carcasses was assessed at slaughter.

No significant improvement in live-weight gain or feed: gain ratio was obtained when either 200 or 700 mg of sodium salicylate/kg was added to the diet. When 700 mg of salicylate was given together with 250 mg Cu/kg diet, the response in growth rate was significantly higher than that obtained from the addition of copper alone.

There was no significant treatment effect on carcass quality as assessed by linear measurements, nor on the dry matter, nitrogen or ash contents of the gluteus medius muscle.

Dexamethasone (16 mg) induced parturition in sheep when injected i n the dam on day 141 of gestation. The mean time of parturition was 49·0 ±2·18 hr after the injection, with 90% of the injected ewes lambed by the 143rd day of gestation compared with the 147th day in the control group. There was no ill effect on the ewe or the lamb born.

The results of earlier work by Breirem have been reanalysed, and some recent results are presented. Breirem's results indicated that for pigs of 16 to 96 kg live weight and fasted for 4 to 9 days, heat production (HP) was related to live weight (LW) according to:

HP = 229 LW0·512

which could be converted to:

HP = 185 LW0·569

This equation gives values for fasting heat production which are about 20% higher than those usually estimated from Breirem's results on pigs of 16 to 196 kg. The recent results, for pigs fasted for 24 hr, were slightly higher than would be indicated by the latter equation. If the values derived from the reanalysis of Breirem's data are related to several estimates of the energy required for maintenance by pigs, values for km% between 87 to 103% are obtained.

The velocity of sound through the limbs of living animals and through tissue excised from carcasses has been measured. The measurements are compared with calibration velocities recommended by the manufacturers of two sonar instruments used to measure the position of tissue boundaries in animals.

The experiment compared the performance of pigs from 11 to 56 days of age when given diets based on maize which had been rolled, or ground through coarse, medium or fine screens, or which were made with maize which had been ground through a medium screen and which were then pelleted or pelleted and crumbled. All diets were given ad libitum.

From 11 days to weaning at 28 days, little feed was eaten and there were no significant effects of the treatments. From 29 to 35 days, daily gain and feed conversion were best on the fine, medium and pelleted diets. From 36 to 56 days, pellets and crumble gave the best performance. There were no significant differences between treatments in the incidence of scouring.

Sarcomere length and fibre diameter were measured in the biceps brachii and sternomastoideus muscles from 35 male mice (5·3-38·0 g body weight). The fore-limbs of each animal were either folded or stretched maximally immediately post mortem and allowed to go into rigor mortis in that position. Unfixed isolated fibres were separated and the sarcomere length and fibre diameter measured. Sarcomere length remained unchanged with increasing body weight irrespective of whether the muscles were in the folded or stretched position. Sarcomere length was shorter in the folded biceps brachii (P < 0·01) and sternomastoideus (P < 0·05) than in the corresponding stretched muscles at all body weights. The results indicate that sarcomere length cannot be used as an indicator of the longitudinal growth of muscle, and that limb position during rigor development is a significant factor in altering sarcomere length.