Development of a nutritional strategy for increasing lamb survival in Merino ewes mated in late spring/early summer.

Abstract

A nutritional strategy for increasing lamb survival in Merino ewes mated in late spring/early summer was evaluated in a commercial flock over two consecutive years (Year 1, n = 680; Year 2, n = 325). The strategy combined the 'ram effect' to synchronise oestrus and hence parturition, plus supplementary feeding of lupin grain for 14 days in the expected early post-parturient period. Supplementary lupin feeding commenced 12 days after the expected start of lambing. Lambing was highly synchronised over a 14-day period commencing 17-19 days after the expected start of lambing, in both years. Supplementary feeding did not affect lamb birthweight in either year but subsequent increases in weight were observed at weaning in Year 1 (1.4 kg; P = 0.06) and tail docking in Year 2 (1.3 kg; P < 0.05). Lamb survival was increased by 7 lambs per 100 ewes exposed to rams in both years. (Year 1 at weaning, NS; Year 2 at tail docking, P < 0.001). It was concluded that the strategy improved both lamb survival and lamb performance possibly due to an effect of lupin supplementation on colostrum and subsequent milk production.