The influence of pre-lamb shearing on lamb birthweight and survival

Abstract

Shearing ewes in mid pregnancy can provide farmers with management and financial advantages. Six experiments conducted at Massey University have collectively shown that shearing ewes at this time can increase lamb birthweight by up to 1.0 kg. When comparisons were made across studies, there was a strong negative relationship between size of the response and the birthweight of control lambs (those from unshorn ewes). The best time to shear ewes to gain a maximum response is likely to be pregnancy day 50 to 100. In a large field trial involving 1002 twin-born lambs, there was a 3% reduction in mortality rate in lambs born to ewes shorn at pregnancy day 67 compared with those lambs born to unshorn ewes (i.e., mortality rates of 15 vs 18%). Pre-lamb shearing offers real advantages to farmers wishing to increase lamb survival at birth. Keywords: ewes, lamb birthweight, lamb mortality, mid-pregnancy shearing