EARLY WEANING OF GRAZING SHEEP .1. GROWTH OF LAMBS

被引:8
作者
FURNIVAL, EP [1 ]
CORBETT, JL [1 ]
机构
[1] CSIRO, DIV ANIM PROD, ARMIDALE, NEW S WALES, AUSTRALIA
关键词
D O I
10.1071/EA9760149
中图分类号
S [农业科学];
学科分类号
09 ;
摘要
In 6 experiments during 1968-1972, Corriedale and Merino breeding ewes were grazed on phalaris (Phalaris tuberosa) pastures at densities of from 8-33 ewes/ha. In experiment 1 the lambs were weaned at 6 or 12 wk of age, or were left unweaned until liveweight was, or approached, 32 kg. The weaned lambs were grazed on a phalaris or a lucerne (Medicago sativa) pasture with abundant herbage, and growth rates were significantly greater on the lucerne. Lambs from ewes grazed at a density of 8.6/ha grew to 32 kg more slowly if weaned at 6 rather than 12 wk, and grew most rapidly if left unweaned; with ewes grazed at 17.3/ha these weaning treatments had the reverse effect. The positive relationship between growth rate of 6 wk and subsequent growth to 12 wk differed between lambs weaned at 6 wk and those unweaned. This effect was examined in the other 5 experiments on lambs weaned within fixed pasture areas at 6 wk by confinement to half the original area. Growth was compared with that of lambs that remained with their ewes on similar total areas not subdivided. The slower the growth rate from birth 6 to wk, the less was the adverse effect of weaning on growth during the subsequent 6 wk. Regression analysis indicated the difference between weaned and unweaned lambs would be 0 if liveweight at the end of the 1st period was 10.6 kg (95% confidence limits .+-. 1.8 kg) representing a growth rate from birth of about 150 g/day. Practical implications are discussed.
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页码:149 / 155
页数:7
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