Effect of accelerated lambing system with melatonin feeding on reproductive performance for 2 years in suffolk sheep raised in Hokkaido

摘要

This study was conducted to determine the effect of accelerated lambing caused by melatonin feeding in the spring on increasing lamb production. Forty-six Suffolk ewes, which conceived last autumn and expected to give birth in February of this year, were divided into 2 groups as follows. Group 1 (treatment, n=23) and Group 2 (control, n=23) ewes were adapted to accelerated lambing and natural lambing, respectively. The accelerated lambing system composed of melatonin feeding for 60-90 days starting in late March followed by ram introduction in May and re-breeding after autumn lambing. The natural lambing system was established so that the ewes were isolated from the rams until autumn resulting in one lambing per year. In these 2 groups, the reproductive performance was evaluated. In the accelerated lambing system, 78 percent of the ewes (18/23) successfully produced 3 sets of lambs every 2 years. The prolificacy per year of the ewes that were involved in the accelerated lambing system was more than that in the control ewes (224 percent vs. 159 percent, p<0.01). The present results demonstrated that the accelerated lambing system with melatonin feeding only once every 2 years could result in greater lamb production than the natural lambing system.