Effect of age and diet on some productive traits of a flock of Sudan Nilotic ewes

The experiment was conducted to assess the productive potentials ofa flock of 42 multipal;"us and 27 primiparous ewes ofthe Sudan Nilotic breed. The latter group (young ewes, YE) were offsprings from the former (parent flock, PF). Each age group was further divided into 2 subgroups referred to as PF~dura, PF-molasses, YE-dura and YE-molasses according to the diet offered. The 2 diets were isocaloric and isonitrogenous, formulated from dura and groundnut-cake (the dura based diet) or molasses and urea (the molasses based diet) as sources ofenergy and protein, respectively. Ewes were designated to subgroups in accordance to their age and live weights. Age of ewes and the diet treatments have no significant effects on the gestation (150.9±3. I days), postpartum anoestrus (42.2± 16.7 days) and lambing interval (206. 1±24.7 days) periods. The experimental groups also showed no significant variations on the number of lambs born/ewe (1.0 to 1.118 lambs born/ewe) and total lambs birth weight/ewe (2.3 to 2.6 kg birth weight of lambs/ewe). Ewes fed on dura-based diet have heavier average lamb weaning weight/ewe (9.9 to 16.3 kg lamb weaning weight/ewe) than their fellow mates ofthe same age group; however the differences were significant only for PF-dura group. Whereas, index 1 (17.3 to 29.2 kg weaning weight of lambs/ewe/year) ofPF-dura group was significantly higher than those ofthe other 3 grollups, which were similar. Ewes of PF groups had significantly higher index 2 (0.623 to 0.998 kg lamb's weaning weight/kg ewe's postpartum weight/year) and index 3 (1.426 to 2.312 kg lamb's weaning weight/kgU75 ewe's postpartum weight/year) than their fellow mates ofthe YE groups. In this context the dura fed groups hud higher indices (2 and 3 than their fellow mates fed on molasses and the differences were significant only between the PF groups. It was concluded that the Nilotic sheep studied have higher productivity indices due to their higher lambing frequency although they have normal litter size, and that nominates as a suitable breed for meat production under intensive systems of the Sudan.