Since comparison of live-weight change of breeding cows is complicated by pregnancy and reproductive synchrony, possible analytical methods for overcoming these problems were reviewed. It was concluded that correction of cow live-weight by subtracting the weight of the gravid uterus and products of conception was biologically and practically meaningful. Two exponential models using polynomial coefficients were derived from published data to predict the fresh weights, at any time during gestation, of the foetus (calculated from calf birth weight) and the gravid uterus and foetal membranes and fluids.

Castrated and entire male buffalo calves of about 2 years of age were made to work by pulling a stone roller weighing 80 kg at a constant speed of about 3 km/h on even ‘Kachha’ ground for 3 h. Blood levels of lactic acid and pyruvic acid and the Icteric index increased, whereas blood levels of bicarbonate and proteins decreased in response to exercise. No change was observed in blood glucose or chloride levels. There was no difference in the concentrations of blood constituents of the two groups.

The silage intake and growth rate of naturally suckled calves after weaning was less than that of similar groups of artificially reared animals that had received lower quantities of milk over the period to 8 months of age. Although the silage intake of all groups was linearly related to the level of herbage intake prior to weaning, those calves consuming least herbage had the higher rate of increase in silage intake. It was concluded that silage intake can be influenced for a considerable time after weaning by the level of herbage consumption achieved during the suckling period.

Thirty-six Corriedale rams were weaned at 3 months of age and subjected to four treatments until 2½ years of age. The treatments consisted of two levels of nutrition, with rams on the high level of nutrition being maintained approximately 15% heavier than those on the low level, and two levels of sexual experience. Sexually experienced rams were kept throughout with ewes that were infertile but showed regular oestrus and inexperienced rams were reared in monosexual groups isolated from females except during periodic mating tests. These 2-h tests were carried out at intervals of 3 to 4 months commencing when the rams were 6 months old. Up to 17 months of age there were no significant differences between treatment groups in the development of ability to serve ewes, except that low nutrition reduced the number of rams which had served ewes at 10 months of age. Between 17 and 28 months of age, rams kept with ewes tended to achieve more serves per test during the breeding season than rams kept without ewes.

A Piétrain × Large White boar and a Large White boar were placed on each of 12 farms where the breeding females were crossbred white sows. Cooperators were requested to obtain 10 litters by each sire and record their performance to slaughter at 60 kg live weight. Breed of sire did not affect litter size or piglet body weight at birth or at weaning, age of progeny at slaughter, carcass mid-line fat depths or colour and condition of the ‘eye muscle’. Piétrain crosses had higher carcass yields (1·8%) and larger eye muscles in cross-section (13·2%) than Large White crosses. They also had less depth of fat above the eye muscle (14 %) but this did not confer any advantage in commercial evaluations.

Five samples from tested pig herds (Large White 1972, 1975, and 1976, British Landrace 1976 and Welsh 1976) were used to estimate the current rate of inbreeding in British pig testing herds. The annual rates of inbreeding (%) were estimated at 0·32, 0·19, 0·24, 0·33 and 0·34 respectively in the five samples. Overall average estimates of 0·49 to 0·52% per generation are similar to estimates from other pig populations reported in the literature. Coefficients of relationship within farms were calculated for various sib and non-sib groups and these were used to estimate the genetic contributions to the variance components in the analysis of variance of test records.

The nutritive value of wild oats has been examined in two trials with growing rats. Feed consumption was reduced with diets containing 50 % wild oats and dry-matter digestibility was lower (76 and 73 %) with two diets containing 25 and 50 % wild oats compared with diets containing 25 and 50% barley (80·2 and 81·1 %). Live-weight gain was depressed when diets contained more than 45 % wild oats and it can be predicted that growth and feed conversion ratios of mono-gastric animals fed on diets containing high levels of wild oats are liable to be affected adversely. Biochemical studies indicated that any reduction in growth rate could not be attributed readily to specific toxic effects.

ANIMAL PRODUCTION, Volume 25, part 2, pp. 193-208