Three groups, each of 12 West African Dwarf ewes weighing 17·5 kg at mating, had mean daily digestible organic matter intakes over the final 7 weeks of pregnancy of 249, 435 and 538 g/ewe (Treatments I, II and III respectively). Mean plasma concentrations in Treatments I, II and III were: glucose, 384, 527 and 538mg/l; non-esterified fatty acids (NEFA), 672, 441 and 427 μequiv/1; and ketones, 44·1, 30·5 and 27·3 mg/1. The differences in all metabolites between Treatment I and Treatments II and III were significant (i) <0·001). The mean birth weights of the single lambs from ewes in Treatments I to III were 1·1, 1·7 and 1·8 kg, those from ewes in Treatment I being significantly lighter than those from ewes in Treatments II and III. Lamb birth weights were significantly and positively related to energy intake and to plasma glucose concentrations, and significantly and negatively related to plasma NEFA and ketone concentrations.

The results indicate that the effect of undernourishment during late pregnancy in West African Dwarf sheep may be greater than in European breeds, and that the concentrations of blood metabolites may have a use in monitoring and regulating nutritional state in this genotype.

Crossbred ewes in which the oestrous cycles had been synchronized by the use of progestagen-impregnated vaginal sponges were mated with Suffolk rams either as a single group of 68 ewes (G) or as four subgroups of 17 ewes (S) in 2 years. Ram:ewe ratio was 1:17 in both treatments. G rams performed more mounts and services than S rams. Non-return rate and lambing rate was better for S than G ewes, especially in Year 1, when fewer G ewes were served. Mating activity was greater in Year 2 than Year 1; prolificacy was also markedly improved.

The use of the ‘anti oestrogen’ clomiphene to increase the ovulation rate of the sheep was investigated. Although in most trials clomiphene had a positive effect, this effect was small and inconsistent—especially n i relation to dose. It was concluded that the present approach would not lead to a simple technique to increase ovulation rate and the number of lambs born.

Two groups of 14 intact male weanling beef breed calves were each fed 1·45 kg oat hay daily and concentrates ad libitum, in a 158-day feeding trial. Group ‘a’ received 35 p.p.m. monensin in the concentrate. Group ‘b’ served as a control.

Average daily gain was 1·28 and 1·27 kg, dressing percentage was 58·1 and 58·0, daily intake of concentrate was 8·10 and 8·79 kg and conversion ratio of metabolizable energy into live weight was 74·53 and 81·30 MJ/kg for the monensin and the control group respectively. The percentage of acetic acid in rumen liquor was reduced and that of propionic acid increased very markedly. As a result the acetic acid: propionic acid ratio was reduced from 3·2 in the control group to 1·8 in the monensin group. No peculiarity in the response of intact male cattle to monensin was observed.