Abstract

Several studies have shown that lambs born to mid-pregnancy shorn ewes are heavier at birth than those born to unshorn ewes (Morris et al. 2000, Kenyon et al. 2002a,b) but, the mechanism responsible has not been identified. Morris et al. (2000) observed elevated maternal triiodothyronine (T3) concentrations over a 20-day period after shearing at mid-pregnancy in both single- and twin-bearing ewes and subsequently found an increased birthweight in the singletons. Symonds et al. (1989) also reported maternal T3 and T4 concentrations to be higher in pregnancy-shorn housed ewes although, an altered birthweight was not reported.

PR, Kenyon, TJ Parkinson, DK Revell, ST Morris, and SN McCutcheon

Proceedings of the New Zealand Society of Animal Production, Volume 63, Queenstown, 149-151, 2003