EWE PERFORMANCE AND LAMB LIVEWEIGHT GAINS COMPARED FOLLOWING AUTUMN AND SPRING LAMBING

Abstract

A flock of 370 Dorset x Romney ewes with up to 96% autumn lambtng was developed without the aid of hormones. Data from flock and experimental records were used to compare the performance of autumn- and spring-born lambs and their dams. Preliminary findings for three seasons show that ewes lambed in autumn had a greater spread of lambing, lower litter size and fewer perinatal lamb deaths. Growth of suckling lambs was similar in winter and spring. After weaning, autumn-born lambs grew faster than spring~born lambs of the same age (104 v 34 g/hd/day). The proportion of lambs reaching killable weights by January was 90% and 10% for autumn and spring lambs respectively. Keywords: Lambing time, autumn, spring, lambing performance, lamb liveweight gain.