THE EFFECT OF DIFFERENT LEVELS OF DRY SEASON SUPPLEMENTARY FEEDING ON THE REPRODUCTIVE PERFORMANCE OF YANKASA SHEEP IN A TWICE-YEARLY LAMBING PROGRAMME

Résumé

Ninety-four pregnant Yankasa ewes were divided into 3 groups and fed;(1) 0, (2) 200 or (3) 400 g/head/day of a concentrate supplement in addition to 6 h grazing daily, from 35.9±2.0 days before, to 98. 122.0 days after lambing in the dry season between 2 Jan vary and 15 May 1984 in Zaria, Northern Nigeria. There were no significant differences (P>0.05) bet den 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 increased significantly (P<0.05) with each increase in level of supplementation: 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 98.1±2.0 days postpartum 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.