The influence of four diets and two remating intervals (1 or 9 days after parturition) on several milk and production traits was studied in 73 lactations of 46 Californian C? × New Zealand $ does. Three diets were formulated to provide increasing levels of fibre concentration (180, 202 and 238 g acid-detergent fibre per kg dry matter (DM)); a fourth diet contained added pork lard (35 g/kg) at the lowest level of fibre. The energy: protein ratio was maintained between 72 and 84 kj digestible energy (DE) per g digestible protein.

The DE intake increased significantly when fat was included in the diet but was not affected by dietary fibre concentration. An increase in the DE content of the diet tended to decrease food conversion ratio at a mean rate of 0·16 kg/kg per MJ/kg DE. Fat addition also improved milk yield, litter weight at 21 days and survival index, mainly when litter size was higher than nine pups born alive. Neither live-weight gain nor prolificacy of does were affected by any of the variables studied.

The type of diet did not affect milk DM, crude protein, fat and energy concentrations, the mean values being 287·8, 116·1, 134·2 g/kg and 27·73 MJ/kg, respectively. The proportions of short- and medium-chain fatty acids in milk fat were not affected by type of diet. The effect of fat addition on milk fat composition was limited to the long-chain fatty acids, mainly C18: 0 and C18: 1. These changes in addition to differences in milk intake could also affect the survival index of pups.

Does remated 1 day after parturition showed a lower total milk yield than those remated 8 days later, the decrease being more apparent at the end of lactation. Remating interval did not affect the other variables studied.

A study was made of the concentration of insulin-like growth factor-l (IGF-I) in the plasma of Jersey cows differing in genetic merit for milk and milk fat production. Plasma IGF-I concentrations exhibited an annual cycle and from this study it is concluded that, in the Jersey breed, selection for increased milk and milk fat production, with the correlated responses of increases in mature live weight and live-weight gain, will not be accompanied by increased plasma IGF-I concentration.

Over 3 years, in Greyface ewes stocked at 10 or 15 per ha and mated in October (early) or November (late), lamb production at birth was related to the pattern of live-weight change of the individual ewe about mating. Based on weighings at 1·5- to 3-week intervals, ewes were grouped according to whether they were gaining (114 ewes), losing (221) or apparently maintaining weight (339) at the time of mating. Ewes losing weight produced significantly fewer lambs (1·58) than did ewes maintaining weight (1·78) while both produced significantly fewer lambs than did ewes gaining weight (1·96). Differences in lamb production between years (year 1 = 1·84, year 2 = 1·71, year 3 = 1·70) and times of mating (early = 1·82, late = 1·67) can be explained in terms of live weight at mating and the different proportions of ewes gaining, maintaining and losing weight. On the basis of earlier studies, it is suggested that the effect of direction of live-weight change operated on failure to conceive or on total loss of multiple-shed ova and was more important pre-mating than post mating.

The true digestibility of protein from diets containing one of the protein-rich foodstuffs, sunflower oil cake, cottonseed oil cake, maize gluten meal and fish meal, was determined in chickens and in the small intestine of sheep. With the exception of maize gluten meal, a close correlation was found between digestibility in the two species (r = +0·98; P < 0·05) and in the sheep small intestine between the true digestibility of utilizable nitrogen and acid-detergent insoluble nitrogen content of the diet (r = -0·96; P < 0·05).

One hundred and eighty-four Large White × Landrace pigs were transported 192 km to slaughter at stocking densities of either 0·3 or 0·4 m2 per 100 kg live weight and at ambient temperatures of >14°C or <10°C. After holding for 3 h in lairage and slaughter by normal practices, samples of m. semimembranosus were removed 45 min after exsanguination. Overall, pigs transported under cold conditions had a slightly lower mean pH45 (0·12 difference, P < 0·05) in the muscle but there were no effects of treatment on ultimate pH or R-value, a measure of the ratio of high energy phosphate compounds to their metabolites. Over 11% of the pigs had ultimate pH values 5·9. This may imply that the pre-slaughter handling had led to some material glycogen depletion. In view of the lack of major effects of stocking density or temperature during transport, it is likely that factors other than the treatments were contributors to this condition and were more important in determining subsequent meat quality.