Protein and Energy Requirements of Lambs, Weaned at Six to Eight Weeks of Age as Determined by Growth and Digestion Studies1

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Abstract
Eighty Hampshire and Hampshire × Rambouillet lambs were fed individually in three experiments of 8 or 9 weeks duration to determine the protein requirement of early-weaned lambs and also to obtain information on the optimum energy content of rations for such lambs. The lambs were weaned at an average age of 5.7, 7.4 and 8.3 weeks and at an average weight of 15.9, 18.2 and 20.4 kg. in experiments I, II and III, respectively. All rations were fed in pelleted form, and the protein content ranged from 10.4 to 16.7%. With the exception of experiment II in which the rations used for the three treatments were based on a 55:45 concentrate-to-roughage ratio, lambs in all of the treatments were fed high-energy rations based on a 75:25 concentrate-to-roughage ratio. Two digestion trials were conducted as part of experiment II to obtain information on the effects of protein and energy content of the ration on the apparent digestibility of these nutrients. Apparent digestibility of both protein and energy were increased significantly due to increased protein and energy content of the ration. Protein content of the ration was without significant effect upon rate of gain or efficiency of feed conversion, when measured on the basis of either 8- or 9-week feeding periods. However, rations containing between 12 and 14% protein resulted in more rapid gains during the first 28 days following weaning than rations with lower protein levels. Rations containing 16.5 to 16.7% protein did not support more rapid or more efficient gains than rations containing 13.5 to 14% protein. Rations based on a 75:25 concentrate-to-roughage ratio supported significantly (P< .01) greater and more efficient gains of lambs weaned at 7.4 weeks of age during the first 4 weeks than did rations based on a 55:45 concentrate-to-roughage ratio. Over the 8-week period gains were greater with the higher concentrate ration than with the lower concentrate ration. However, these differences were not significant. Copyright © 1966. American Society of Animal Science . Copyright 1966 by American Society of Animal Science

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