Effect of live-weight and live-weight change on the lambing performance of ewes

Abstract

A flock of 320 Border-Leicester × Merino ewes was used to study the effects of pre-flushing and flushing treatments on subsequent lambing performances during the years 1958, 1959 and 1960. The flock was kept on non-irrigated perennial pastures in southern Victoria. In 1958 groups of ewes that lost a mean of 17, 5 and 0 lb. during the 4 weeks immediately prior to flushing gave average lambing percentages of 94, 98 and 101, respectively. In 1959 and 1960 flushing for a period of 3 weeks immediately prior to joining produced increased lambing percentages of 13 and 9, respectively. These increases were due almost entirely to increased twinning rates. The response to flushing was not related to the live-weight changes that occurred during flushing. However, the live-weights of the ewes at joining, and, to a lesser extent, before flushing, were related to subsequent lambing performances. The heavier ewes gave more twins than did the lightweight ewes.