试验选用体重（9.5±0.3） g的草鱼幼鱼，随机分成6个组，每组3个重复，每个重复20尾；以花生仁粕、酪蛋白及明胶为蛋白质源，分别饲喂缬氨酸水平为7.3~22.3 g/kg的6组等氮半精制饲料（粗蛋白质含量为32%），经70 d的生长试验研究其日粮缬氨酸的最适需求量。试验结果表明：日粮缬氨酸水平对草幼鱼的增重率、特定生长率、蛋白质效率、肌肉RNA/DNA比率、鱼体常规成分组成、消化酶活性、肝胰脏谷草-谷丙转氨酶和谷氨酸脱氢酶活性以及血液学指标都有显著的影响(P<0.05)。随日粮缬氨酸水平的增加，增重率、特定生长率、蛋白质效率及肌肉RNA/DNA比率均呈先升后降趋势，均在16.3 g/kg组达到最大值(P<0.05)。以增重率、特定生长率、肌肉RNA/DNA比率为基础对饲料缬氨酸水平进行二次回归分析，确定草鱼幼鱼日粮(32%粗蛋白质)缬氨酸适宜需要量分别为15.6、15.1及16.0 g/kg（日粮基础）或48.8、47.2及50.0 g/kg（日粮蛋白质基础）。

A 70-day feeding trial was conducted to estimate the optimum requirement of dietary valine for juvenile grass carp using six isonitrogenous diets (32% protein) with peanut meal, casein, and gelatin as protein resource supplemented with six graded levels of coated valine (from 7.3 to 22.3 g/kg of dry diet). Each diet was randomly assigned to three replicates of 20 fish each with average weight of (9.5±0.3) g. The results showed that weight gain ratio (WGR), specific growth rate (SGR), protein efficiency ratio (PER), body composition, RNA/DNA ratio in muscle, digestive enzyme activity, alanine amino transferase (ALT) and aspartate amino transferase (AST) and glutamate dehydrogenase (GDH) activity in hepatopancreas and hematology were all significantly (P<0.05) affected by the dietary valine levels. WGR, SGR, PER and RNA/DNA ratio in muscle were significantly increased with valine level increasing from 7.3 to 16.3 g/kg of diet (P<0.05), and then decreased. Second-degree polynomial regression analysis for WGR, PER and RNA/DNA ratio in muscle indicated that the optimum requirements of dietary valine of juvenile grass carp were 15.6, 15.1 and 16.0 g/kg of diet (48.8, 47.2 and 50.0 g/kg of dietary protein), respectively.