Published online by Cambridge University Press: 02 September 2010
In a Welsh Mountain flock of 104 ewes, 51 had their tails tied aside for the duration of one oestrus. Tail-tying significantly increased the conception rate at this oestrus. It also significantly increased the mean litter size of ewes superovulated with 1000IU PMSG from 1·70 to 2·33. It is suggested that the most likely reason for this increase in the number of multiple births was an increased number of ejaculations per oestrus. Perinatal mortality was high in lambs from multiple births. The effect of PMSG and tail-tying was to increase the lambing percentage from 77 to 120.