The influence of a low-nutrient intake after mating on gestation and perinatal survival of lambs

Abstract

The effects of a low-nutrient intake during the first trimester of gestation on inutero and perinatal survival of lambs were investigated in Blackface ewes. The ewes were all in good condition (score 3 to 3 1 2 ) at the start of the experiment. The treatment group (T, 15 ewes) was given about 15% of the recommended nutrient allowances for maintenance during 60 days post mating. The control group (C, 10 ewes) was given the full maintenance allowance for the same period. At other times ewes in both groups received equal and adequate levels of nutrients. The T group lost almost 9 kg live-weight on average during the restricted feeding period and lost 0·8 unit in condition. There was some compensatory weight gain after the regime finished, but the T ewes were still a little lighter than their original live-weight by parturition. There was no evidence of embryo mortality as a result of the restricted regime. However, lambs from the experimental ewes were less viable, had a lower birth-weight and showed evidence of intrauterine growth retardation. Plasma progesterone profiles showed evidence of elevated levels in the T ewes during days 20 to 25 post coitum, significantly higher than those of the C ewes.