The effects of pregnancy and lactation on wool production and liveweight in Polwarth ewes

Abstract

Groups of Polwarth ewes which 1. were barren, 2, were pregnant but aborted with prostaglandins in early pregnancy, 3. lambed and reared a single lamb and 4. lambed but had their single lamb removed soon after birth, were used to estimate the effects of pregnancy and lactation on wool and Iiveweight. Pregnancy plus lactation reduced liveweight (17 per cent), wool growth rate (9 per cent) and clean fleece weight (11 per cent) ; pregnancy alone reduced liveweight (10 per cent), wool growth rate (7 per cent) and clean fleece weight (10 per cent) and its effects were greater than those of lactation in each of the characters studied.

Effects of pasture allowance in winter on liveweight, wool growth, and wool characteristics of Romney ewes

“…Estimation of the effects of pregnancy category from the wool production and wool characteristics of ewes naturally having 0, 1 or 2 lambs in utero can be criticised because it ignores possible inherent differences between the ewes in the three categories. However, Reid (1978) reported similar patterns of wool growth for ewes that were naturally nonpregnant or artificially aborted on days 23 -24 of pregnancy. No equivalent data have been reported for ewes carrying single or twin lambs.…”