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Excessive Levels of Dietary Protein and Energy Induce Lack of Growth Promoting Effects of Clenbuterol in Broilers |
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Y. Hamano, S. Yamazaki, K. Kume, S. Kobayashi, Y. Terashima |
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| Abstract |
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The present study examined the effects of excessive dietary protein and energy on growth response to clenbuterol in broilers. The chicks were allocated into 6 groups at 14 d old, and used for a 3횞2 factorial experiment. Birds were fed six diets, the control diet containing 21% crude protein (CP) and 3,100 kcal of metabolizable energy ME/kg, a high protein (30% CP) or a high energy (3,500 kcal/ME/kg) diet, with or without 1 ppm clenbuterol, for 18 d. Clenbuterol feeding markedly decreased (p < 0.05) boy weight gain by 23% in the high energy group. Feed intake was also decreased (p < 0.05) by clenbuterol administration across diet treatments. Abdominal fat weight was reduced (p < 0.05) by clenbuterol only when chickens were fed the high energy diet. Clenbuterol increased (p < 0.05) leg muscle weight in the control diet group, but decreased (p < 0.05) it in the high energy group. Muscle protein concentration was increased by 11% in leg muscle only of the birds at the high energy level. In leg muscle, clenbuterol enhanced the protein/ DNA ratio by 18%, except for the high protein group. These results indicate that feeding a diet containing excessive amounts of protein and more energy than normal did not necessarily improve growth response to clenbuterol. |
| Keywords:
棺-Adrenergic Agonist; Clenbuterol; Dietary Protein; Dietary Energy; Growth Performance |
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