Fifty-six Merino d'Aries and 56 Romanov × Merino crossbred lactating ewes were divided into two treatment groups, one (T1) with a ewe-to-ram ratio of 48: 1 (24 Merino and 24 crossbred) and the other (T2) of 64: 1 (32 Merino and 32 crossbred).

Intravaginal sponges with 40 mg FGA (Searle) were inserted in two subgroups at 8-day intervals and withdrawn after 12 and 16 days in situ, in four equal groups at 4-day intervals. A dose of 400 IU pregnant mare's serum gonadotrophin (PMSG) was applied at sponge withdrawal.

Fertility after two oestrous cycles was equally satisfactory in both treatments, though it was lower in treatment group T2. This could be due to the significantly low (P<0·01) number of Merino ewes raddled by the T2 ram (0·33 Merino against 0·92 crossbred) suggesting preferential behaviour by the ram in this treatment.

Comparisons between breeds show a slight superiority in the fertility of crossbred ewes and a highly significant superiority in prolificacy These results suggest that using the described method, 2% of rams seems more than adequate to mate with progestagen-synchronized ewes with a satisfactory fertility level. It is, however, recommended to use homogeneous groups of ewes.

Weaned single-suckled calves (male castrates) were offered a finishing diet which included 2·3 kg/day bruised barley (F) or a similar diet with the cereal supplement omitted (R) during the main winter feeding period. Some diet R steers had a subsequent grazing period and were re-housed for a second winter when the diet included a cereal supplement. The treatments caused differences in growth rate, distribution of slaughterings and grazing requirements. Diet R reduced growth rate and the steers took longer to reach slaughter, which was at a higher live weight, than on diet F at the same degree of finish. Steers on diet R produced 4·5% more carcass weight, 8·2% more lean, 4·1 % less fat and 11·2% more bone than those on diet F. They consumed more wet distillers' grains (21·1 %), swedes (25·5%) and grass silage (32·0%) from housing to slaughter but saved 80·0 % of the cereal consumed on diet F.

Ruminal ammonia and blood urea levels were compared in fistulated steers eating paddy straw to appetite and given urea alone, urea plus oxalate, and complexes of urea with either formaldehyde (UFC) or oxalate (UOC), introduced into the rumen in a single daily dose. The solubilities of UFC and UOC in rumen liquor were 23·7 and 4·6% respectively of that of urea. Higher levels of ruminal ammonia and blood urea were recorded on urea than on other supplements.

Young, uncastrated male cattle (initial weight 80 kg, final weight 240 kg) were used to evaluate brewers' dried grains as a protein source (17 or 36% of the concentrate mixture), in comparison with soyabean oil meal (6% of the concentrate mixture). There were no significant effects on feed intake or average daily live-weight gain. The killing-out percentages for the three treatments were 49·2; 48·6 and 46·9 respectively (P < 0·001). There was a lower fat deposition (P < 0·01) in animals receiving the higher level of brewers' dried grains, and the degree of rumen parakeratosis was less (P < 0·001) with the diets containing grains.

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.