Growth and lifetime production of scottish blackface hill ewes in relation to the level of feeding during rearing

Abstract

SUMMARYA study was made of the effects of different levels of nutrition between 3 and 6 months and between 6 and 12 months of age on subsequent growth to mature size, longevity and lifetime production of Scottish Blackface female sheep on a hill farm. Treatment differences between 3 and 6 months were small and resulted in only a 3 kg live-weight advantage for the animals receiving a high level of feeding. Treatment differences between 6 and 12 months were considerable and resulted in a mean 14 kg advantage for animals receiving a high level of feeding. Those animals remained significantly heavier until 42 months of age and significantly larger, as depicted by skeletal measurements, until 54 months of age.A high level of feeding between 3 and 6 months of age had no significant long-term effect on wool growth ewe survival or lifetime lamb production, whereas a high level of feeding between 6 and 12 months of age had a significant positive effect on the mean number of lambs born per ewe over five lamb crops. This effect was not maintained to weaning, due to an apparently greater lamb mortality. Treatment effects on ewe survival and on flock lifetime production, although considerable, were not statistically different.It is concluded that any advantages of improved feeding during rearing were largely lost through the inadequacy of the adult nutritional environment and only when the latter was not limiting would higher standards of rearing be justified.