本试验通过在饲粮中添加不同水平的过瘤胃保护性亮氨酸，采用大剂量一次性灌注法来测定亮氨酸对绵羊机体蛋白质合成的影响。试验选取绵羊12只，随机分为4组，分别饲喂添加0（对照组）、0.5、1.0和1.5 g/d的瘤胃保护性亮氨酸的饲粮。15 d后，在绵羊颈静脉大剂量一次性灌注L-d5苯丙氨酸并且采集血样及皮肤组织样，90 min后屠宰，取背最长肌、股二头肌和肝脏样品，经前处理后，通过气-质联用仪来测定各组织蛋白质合成率（FSR）及蛋白质合成量。结果表明：瘤胃保护性亮氨酸对绵羊骨骼肌FSR的影响显著（P<0.05），对肝脏FSR则影响不显著（P>0.05）；瘤胃保护性亮氨酸对绵羊骨骼肌及肝脏组织的蛋白质合成量显著增加（P<0.05），以1.0 g/d添加组效果最好。

The experiment was conducted to study the effects of different levels of rumen-protected leucine supplementation on protein synthesis in sheep using the one-time large doses of perfusion method. Twelve sheep were allotted to 4 groups, and fed basal diets added with 0 (control), 0.5, 1.0 and 1.5 g/d of the rumen-protected leucine for 15 days, respectively. After 15 days, all sheep were administered a flooding dose of L-［D5］-phenylalanine in jugular vein and the blood and skin tissue samples were collected. Then the sheep were killed at 90 min to measure the fractional protein synthesis rates (FSR) and the synthesis content of protein in biceps femoris, longissimus dorsi muscle and liver after pre-treatment by GC-MS. The results showed that the sheep fed diets with the rumen-protected leucine supplementation had greater FSR in longissimus dorsi muscle and biceps femoris (P<0.05), but had no significant effects in liver (P>0.05). The rumen-protected leucine significantly increased the protein synthesis in biceps femoris, longissimus dorsi muscle and liver (P<0.05). The results suggested that 1.0 g/d of the rumen-protected leucine supplementation in diet could get the best effects.［Chinese Journal of Animal Nutrition, 2010，22（4）:951-955］