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The nutrition of artificially reared lambs 2. The effect of feed restriction at three stages of growth on growth and carcass composition
Published online by Cambridge University Press: 02 September 2010
Summary
Lambs weaned from the ewe at 2 days of age were fed ad libitum or restricted in each of three periods of growth to a slaughter weight of 35 kg according to a factorial design. Restriction in the milk-feeding period was achieved by reducing the milk allowance (6·4 kg v. 13·6 kg of milk replacer) and after weaning, by restricting the daily allowance of feed.
Restriction of the milk allowance reduced early growth but the effect was partly offset by the higher concentrate consumption of restricted lambs. There was also a tendency for lambs restricted in the milk period to eat more and grow faster when subsequently fed ad libitum. Performance after 15 kg on a diet containing no protein of animal origin was poor and the level of restriction was severe. Overall growth and efficiency from 15 to 35 kg were considerably reduced by any degree of restriction. However, there was no evidence that restriction in the middle period of growth had any effect on the performance of lambs fed ad libitum in the final period. Although carcass weight was not affected by treatment at any stage, restriction in the milk-feeding period and feeding ad libitum from 15 to 25 kg resulted in a greater weight of head, liver, heart and lungs (weighed together). Chemical analysis of the whole minced carcass showed that restriction of milk intake had a significant effect in reducing the carcass dry-matter content. There was also a trend towards a higher energy and fat content of the dry matter. Restriction in the final period increased the protein content of the carcass.
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- Copyright © British Society of Animal Science 1972
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