The effects of different levels of nutrition from weaning to seventeen months of age on the lifetime production of Merino ewes

Abstract

One hundred and seventy-nine ewe weaners from five experimental selection flocks were allocated at random, within sire lines, to one of two groups which were subjected to different nutritional regimes from weaning to 17 months of age. Liveweight and wool production were examined over an eight-year period and survival rate and reproduction data over the lifetime of the ewes. The treatments produced a maximum liveweight difference of 30.5 lb at 14 months of age when the liveweights of ewes receiving a high plane of nutrition averaged 98 lb. There were significant selection flock X plane of nutrition interactions in greasy fleece weight and staple length. Clean fleece weight of sheep on the low plane of nutrition was depressed by 25 per cent at the first shearing, and there were small differences in the fleece weights of low and high plane sheep in the following six years. Death rate, lifetime reproduction, and weaning weight of progeny were not significantly depressed by the low plane treatment.