The effect of different levels of dry season supplementary feeding on the reproductive performance of yankasa sheep in a twice-yearly lambing programme
Ninety-four pregnant Yankasa ewes were divided into 3 groups and fed; (1) 0, (2) 200 or (3) 400 g/head/dat of a concentrate supplement in addition to 6 h grazing daily, from 35.9±2.0 days before, to 98. 1 ±2.0 days after lambing in the dry season between 2 Januuy and 15 May 1984 in Zaria, Northern Nigeria. There were no significant differences (P>0.05) between groups in litter size and adjusted birth weight in the initial lambing 35.9±2.0 days into the experiment although the latter showed consistent increase with level of supplementation. Adjusted 90- day weaning weights increued significantly (P<0.05) With eaeh increase in level of upplementation: 5:5, 7.1 and 8 .6kg for groups 1, 2 and.3 respectively. Correspondingly, the percentage of lambs weaned increased (48.6, 56.4 and 90.7%) while ewe mortality declined (12.9, 10.0 and 3 .0%) With increasing level of supplementation. The percentage of ewes exhibiting oestrus Within 98.l ±2.0 days post-partum increased With level of supplementation: 77 .8, 91.3 and 96.8% for groups 1, 2 and 3 respectively. However, of the ewes showing oestrus, there were no significant differences between groups in post-partum intervals to oestrus and conception. Litter size from matings during the experiment showed non significant increase with level of supplementation. It is concluded that dry season supplementary feeding is essential for optimum reproductive performance of Yankasa sheep in a twice.yearly lambing programme.
(Key Words: Levels, Dry Season, Supplementary, Feeding, Yankasa, Sheep).