本试验研究了日粮添加蛋氨酸（Met）对山羊十二指肠内源氮（EN）和内源氨基酸（ENAA）流量的影响。采用3×3拉丁方试验设计，选用3头安装有永久性瘤胃、十二指肠近端瘘管和颈静脉插管、平均体重为（20±2.5）kg的健康湘东黑山羊为试验动物，饲喂3种Met水平分别为0.15%、0.25%和0.35%的试验日粮，采用同位素方法测定Met水平对山羊EN和ENAA流量的影响。结果显示：当Met添加水平为0.15%时，十二指肠EN和ENAA流量均最低，但是无显著性差异（P＞0.05）。以上结果表明：日粮直接添加蛋氨酸对山羊十二指肠EN和ENAA流量没有显著影响作用（P＞0.05），同位素稀释法测定反刍动物EN流量较为稳定。

The experiment was designed to study the effect of dietary methionine (Met) levels on duodenal flows of endogenous nitrogen (EN) and endogenous amino acids (ENAA) in growing goats fed normal protein-containing diets. Three goats with an average body weight of (20±2.5) kg were fitted with ruminal, duodenal cannulae and jugular veins polyvinyl catheters, and allocated to three dietary treatments in a 3×3 Latin square design. The dietary treatments consisted of a total mixed diet containing three levels of Met which were 0.15%, 0.25% and 0.35%, respectively. EN and ENAA were determined using isotope dilution method. The results showed that the duodenal flows of EN and ENAA were the lowest when the dietary Met level was supplemented at 0.15%, and there were no significant differences on duodenal flows of EN and ENAA (P＞0.05). In conclusion, the duodenal flows of EN and ENAA were not significantly affected by the dietary direct supplementation of Met (P＞0.05), and the isotope dilution method was relatively stable in determination of EN flow.