Feed supplementation improves estrus response and increases fertility of sheep induced to breed out of season
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To test the efficacy on reproductive performance of nutritional supplementation in an out-of-season mating system, 66 adult prolific Barbarine ewes were selected and induced to breed using “ram effect”. The ewes were allocated to two homogeneous groups; each ewe received on a daily basis 700 g of hay and 500 g of barley grains starting 3 weeks before or 1 week after rams’ introduction in group 1 and group 2, respectively. Supplementation ended 1 month after rams’ introduction and mating lasted 60 days. Final live weight 30 days after introduction of rams was higher (P < 0.05) for ewes in group1 (39.45 vs. 36.72 kg). Seven days after introduction of rams, ewes in group 1 recorded higher plasma glucose levels than females in group 2 (4.12 and 3.9 S.E.M. 0.05 mmol l−1). Proportions of ewes which displayed estrus between days 16 and 26 were 48 and 38% in group 1 and group 2, respectively (P < 0.05), and those which had a normal induced cycle (16–17 days) were 25 and 11% in group 1 and group 2, respectively (P < 0.05). Fertilities were higher (P < 0.05) for ewes in group 1 than in group 2 (91.17 vs. 75.75% and 97.1 vs. 81.8% for fertility at induced estrus and total fertility, respectively). It is concluded that a timed supplementation starting 3 weeks before introduction of rams is effective in yielding high reproductive performance for the prolific strain of the Barbarine breed.