Improving lamb birthweight through mid- to late-pregnancy
shearing: a review of recent studies
P.R.Kenyon, S.T. Morris, D.K.Revell and S.N. McCutcheon
Institute of Veterinary, Animal and Biomedical Sciences, Massey
University, Palmerston North, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1999, 59: 70-72
A series of five experiments have been conducted at Massey
University to determine whether mid- to late-pregnancy shearing of ewes
might provide an opportunity to increase lamb birthweights and enhance
survival, particularly of multiple-born lambs, under New Zealand's
pastoral conditions. Although birthweight responses were seen in most
studies, they were not consistent with respect to the magnitude of the
response or its occurrence in singles vs twins. However, when comparison
was made across studies there was a strongly negative relationship
between the size of the response and the birthweights of control lambs
(those from unshorn ewes). We conclude that responses to mid- to
late-pregnancy shearing are likely to be greatest when fetal growth in
unshorn ewes is limited by maternal constraint.
Keywords: NZSAPAB;
Birthweights; survivability; pregnancy; shearing.
Last Updated 06-08-1999
