THE EFFECT OF MELATONIN TREATMENT ON REPRODUCTIVE EFFICIENCY IN AN ACCELERATED LAMBING SYSTEM

A trial, which involved 917 ewes, was conducted to examine whether rep roductive traits could be improved in an accelerated lambing system wi th 3 lambing seasons per year by subcutaneous melatonin treatment. Fer tility (ewes lambed per ewes put to the ram), litter size and the inte rval between melatonin application date and lambing season (15 Februar y to 15 March), fertility was 16% higher in melatonin-treated ewes com pared to untreated ewes (P>0,05). Season or month of application there fore seems to be an important factor with regard to the response. It i s concluded that melatonin treatment in accelerated lambing systems is further complicated by the presence of pregnant and lactating ewes, w hich makes the value of commercial use thereof doubtful.