Effects of dietary phenylalanine levels on performance and melanin contents in tissues of Taihe silky fowls aged from 5 to 12 weeks | 日粮苯丙氨酸水平对5～12周龄泰和乌骨鸡生产性能及组织黑色素含量的影响

chinois. 研究日粮苯丙氨酸水平对5～12周龄泰和乌骨鸡生产性能和组织黑色素含量的影响。选用28日龄泰和乌骨鸡81只，随机分成3组，每组设3个重复，每重复9只鸡（公母各半），饲养至12周龄。在5～8周龄3个处理组中日粮苯丙氨酸水平分别为6.79，9.14和11.49 g/kg，在9～12周龄3个处理组中日粮苯丙氨酸水平分别为6.37，8.28和10.19 g/kg。日粮苯丙氨酸水平对5～8周龄和9～12周龄泰和乌骨鸡的平均日增质量、平均料重比、平均日采食量均无显著影响（P0.05）。日粮苯丙氨酸水平显著影响8周龄泰和乌骨鸡胸肌的黑色素含量（P0.05），但对腿肌和皮肤的黑色素含量均无显著影响（P0.05），日粮苯丙氨酸水平为9.14 g/kg时，胸肌黑色素含量最高。日粮苯丙氨酸水平显著影响12周龄腿肌和皮肤的黑色素含量（P0.05），但对胸肌的黑色素含量无显著影响（P0.05）；腿肌黑色素含量以6.37 g/kg苯丙氨酸水平组最高，而皮肤黑色素含量以8.28 g/kg苯丙氨酸水平组最高。通过调节日粮苯丙氨酸供给水平，可改善泰和乌骨鸡体内黑色素的沉积而不影响其生产性能。

anglais. This study was conducted to investigate the effects of dietary phenylalanine levels on performance and melanin contents in tissues of Taihe silky fowls aged from 5 to 12 weeks. Eighty one 28-day-old Taihe silky fowls were randomly allotted to 3 groups with 3 replicates of 9 birds each and were raised to 12 weeks of age. The birds were fed diets with one of phenylalanine levels of 6.79, 9.14 and 11.49 g/kg at 5-8 weeks of age, and 6.37, 8.28 and 10.19 g/kg at 9－12 weeks of age respectively. The average daily gain (ADG), feed to gain (F/G) and average daily feed intake (ADFI) were not influenced by dietary phenylalanine levels at 5－8 and 9－12 weeks of age (P0.05). The melanin content in pectoral muscle was significantly influenced (P0.05), but in leg muscle and skin were not affected by dietary phenylalanine levels at 8 weeks of age (P0.05). The highest melanin content in pectoral muscle was observed when the dietary phenylalanine level was set at 9.14 g/kg. The melanin contents in leg muscle and skin were significantly influenced (P0.05), but in pectoral muscle was not affected by dietary phenylalanine levels (P0.05) at 12 weeks of age. The leg muscle and skin had highest melanin content when the dietary phenylalanine levels were set at 6.37 g/kg and 8.28 g/kg at 9－12 weeks of age respectively. The melanin contents in Taihe silky fowls could be improved by controlling the dietary phenylalanine to appropriate levels with no negative effects on performance.