中文摘要：

研究甜菜碱代替蛋氨酸对肉鸡生长性能及蛋白质代谢的影响。1800只1日龄AA肉仔鸡随机分为6个组，每组3个重复，每重复100只鸡，试验持续6周。6个处理组分别为Ⅰ组即对照组，按标准添加肉鸡需要的蛋氨酸，Ⅱ、Ⅲ组为甜菜碱分别代替15％、25％总蛋氨酸组，Ⅳ、Ⅴ组分别为总蛋氨酸减少15％、25％且不添加甜菜碱组，Ⅵ组为甜菜碱代替全部添加的蛋氨酸组，甜菜碱均以1：2的比例代替蛋氨酸。结果表明，除Ⅵ组外，各组肉鸡生长性能相近（P〉0．05），25％蛋氨酸替代纽GH和IGF—Ⅰ分泌量最高，尤其IGF—Ⅰ含量显著高于其它各组（P〈0．05）。此外，15％、25％总蛋氨酸替代组，有提高胸肌重、胸肌率，胸肌和肝脏中粗蛋白含量和血清总蛋白含量以及碱性磷酸酶活性，降低尿酸含量和肌酸激酶活性的趋势。根据试验结果，甜菜碱可以1：2的比例代替肉鸡日粮25％总蛋氨酸，既有利于肉鸡生长又可降低生产成本。

英文摘要：

The purpose of this study was to examine the effects of substituting methionine with betaine on growth performance and protein metabolism of broilers. A total of 1 800 one - day - old Arbor Acres broiler chicks were divided randomly into 6 treatments groups with 3 replicates of 100 chicks each. The experimental period was 6 weeks. Group Ⅰ was control group in which methionine was added accordding to the feeding standard of broilers; groups Ⅱ and Ⅲ, betaine was added to replace 15% or 25% of methionine; groups ⅣandⅤ, methionine was decreased by 15% or 25% without adding betaine; and group Ⅵ, betaine was added to replace all methionine. The amount of betaine as the substitute of methionine was at a ratio of 1 ： 2. Results ： The growth performances are similar in the groups except group Ⅵ, and the contents of GH and IGF - Ⅰ of 25% methionine replacement group are higher, especially the content of IGF- Ⅰ is significantly higher than other groups （P 〈 0.05）. In addition, substituting 15% or 25% of total methionine with betaine can increase breast meat weight, breast meat yield, crude protein content of breast meat and liver, total protein content and alkaline phosphatase activity, while decrease uric acid content and creatine kinase activity. In conclusion, Using betaine to replace 25% of total methionine of broiler diets at an amount ratio of 1 ： 2 can promote growth performance of broilers and reduce production cost.