Whole wheat grain feeding of Merino ewes. 3. Influence of level of wheat and vitamin A on wool growth in pregnancy and lactation

Abstract

In experiment 1, ewes were fed three levels of wheat in pens, with or without vitamin A, from joining to weaning. The wheat levels ranged from 3.4 to 4.6 kg head-1 week-1. Control groups were run on native pasture. In experiment 2 three levels of wheat, which ranged from 3.9 to 7.1 kg head-1 week-1. were fed to ewes from joining to weaning. At each wheat level two groups were fed wheat in pens (wheat/ pen); another group was fed wheat in small paddocks (wheat/paddock). One of the wheat/pen groups received vitamin A. A control group was run at pasture. Vitamin A had no effect on wool traits except on wool yield in experiment 2. Clean wool weight and staple length increased linearly with increasing wheat intakes in both experiments. The relationship between fibre diameter and wheat level was linear in experiment 1 and curvilinear in experiment 2. In experiment 2 there were differences between wheat/pen and wheat/paddock groups in all the wool traits measured. In experiment 1, wool growth rate was reduced by 40 per cent in the wheat groups and by 44 per cent in the pasture groups during late pregnancy and lactation. In experiment 2, compared with early pregnancy, wool growth rate was reduced by 11 per cent and 31 per cent in the wheat groups during late pregnancy and lactation respectively.