ABSTRACT

1. Four experiments were conducted to determine the 4th limiting amino acid (AA) in maize–soybean meal-based diets.

2. Deletion assay methodology was used to quantify performance and carcase trait responses to potential deficiencies in essential and conditionally essential AA caused by reductions in dietary crude protein of maize–soybean meal-based diets from 202.9 to 186.5 g/kg.

3. The deletion of Val, Phe and Gly + Pro resulted in negative effects on live performance and carcase traits for male broilers, whereas AA deletion only affected wing weights for females with no response on live performance.

4. Further experimentation could not duplicate a response to Phe or Pro in male broilers.

5. Valine was identified as the potential 4th limiting AA in maize–soybean meal-based diets and was not found to be co-limiting with Ile.

摘要

1.进行了四个实验以确定玉米-豆粕型日粮中的第四种限制性氨基酸（AA）。

2.删除测定法用于量化性能和屠体性状对玉米和豆粕型日粮的日粮粗蛋白从202.9 g / kg降低至必需和有条件必需氨基酸的潜在缺陷的反应。

3. Val，Phe和Gly + Pro的缺失对雄性肉鸡的实时性能和car体性状造成负面影响，而AA缺失仅影响雌性鸡的翅膀重量，而对实时性能无反应。

4.进一步的实验无法复制雄性肉鸡对Phe或Pro的反应。

5.在玉米-豆粕型日粮中，缬氨酸被确定为潜在的第四限制AA，但未发现与Ile同时存在。