Does an increase in lamb birth weight though mid-pregnancy
shearing necessarily mean an increase in lamb survival rates to weaning?
P.R. KENYON, S.T. MORRIS AND S.N. McCUTCHEON
Institute of Veterinary, Animal and Biomedical Sciences, Massey
University, Palmerston North, New Zealand.
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NZSAP 2002 Abstract No. 15
Proceedings of the New Zealand Society of Animal Production 62:
53-56
Lambing percentages in New Zealand have risen over the past
decade and will most likely continue to rise, while the price for lamb
remains high in relation to wool. Any technique that can increase the
birth weights of lightweight multiple-born lambs may increase survival
rates to weaning. Mid-pregnancy shearing as a possible technique to
increase lamb survival under commercial conditions was examined in the
present study. Mid-pregnancy shearing was found to significantly (4.7 vs
5.1kg, P<0.05) increase the birth weights of twin-born lambs but had
no effect on birth weight of singletons or triplet-born lambs. Both the
magnitude of the response, and the fact that it did not occur in all
birth ranks, are consistent with previous mid-pregnancy shearing
studies. Mid-pregnancy shearing had no significant effect on lamb
survival rates to weaning. To achieve an increase in survival rate to
weaning through an increase in lamb birth weight alone, the lamb must be
born within a birth weight survival range below optimum, and the
increase in birth weight must be large enough to move a significant
proportion of these lightweight lambs into a higher survival rate range.
Keywords: NZSAPAB;
mid-pregnancy shearing, lamb birth weight, lamb survival
Last Updated 30/07/2002
