草鱼幼鱼对缬氨酸需要量的研究

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).

Research on Dietary Valine Requirement of Juvenile Grass Carp(Ctenopharyngodon idella)

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 20fish 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.