The effect of mating pressure on characteristics of the ejaculate in rams and on reproductive performance in ewes

Abstract

Table 1 shows data for ewes mated in the first 17-day cycle. The variation in the number of ‘ewes mated by each ram within groups was low, indicating that there was little effective competition between rams. In all groups a high proportion of ewes were mated by more than one ram; this was most marked at a ram :ewe ratio of I :50. Eighty-four per cent of ewes mated by 2 or 3 rams in the first cycle lambed to service at that time. Of those ewes mated by one ram only 77% lambed to that service. Lambing performance was markedly similar in all groups. The main conclusions from examinations of the semen samples were :