一次注射同位素检测内源氨基酸损失量的方法学研究

本项目依据同位素稀释定律及代谢动力学原理，拟以肉仔鸡为试验动物，探索性研究一次注射同位素检测内源氨基酸损失量的可行性，以期建立一种测定采食实际含氮饲粮时内源氨基酸损失量的新方法，为获取饲料氨基酸真实消化率提供基础数据，改进配合猪禽饲粮的准确性，提高饲料利用率，减少排泄物中氮素对环境的污染。

This study established a new method for determining endogenous amino acid losses by a sinle injection of 30μCi[3H]Leu/kgBW .Three sets of young hens and broilers received six diet treatments. The diets were on fast (FAS), and force-fed nitrogen-free diet (NFD), NFD+3.20% enzyme hydrolysed casein (EHC), semi-synthesized diets with 5% and 20% crude protein (CP) in which soybean meal (Sol.) was the sole nitrogen source, and semi-synthesized diet with 20% CP in which cotton seed meal (Sol.) was the sole nitrogen source. After force-fed, 30μCi[3H]Leu/kgBW was injected subcutaneously, the excreta in the following 48hr were totally collected, and venous blood samples were taken at 5 min, 30 min, 4 hr, 24 hr, 36 hr and 48 hr. The study showed that the ratios between specific radioactivity (SR) of endogenous leucine in excreta (SRe) and SR of free leucine in plasma (SRp) kept constant, no matter what kinds of diets the birds ate. This made it possible to determine the endogenous amino acid losses (EAAL) of practical diets when NFD or FAS was taken as the reference.