大鳞鲃幼鱼蛋白质的需求量

Dietary protein requirement of young Barbus capito

设计7个蛋白质水平饲料（30.24%,33.22%,36.23%,39.33%,42.15%,45.33%和48.12%）,对大鳞鲃（Barbus capito）幼鱼的饲料蛋白质需要量进行研究。每个处理组设3个重复,每重复30尾鱼。初质量为（11.07±2.42）g的试验鱼放入水族箱（220L）中,循环水饲养（流速2L/min）,饲养周期56d。结果显示,当饲料蛋白质水平从30.24%增加到42.15%时,增重率和特定生长率逐渐升高；蛋白质水平在42.15%～48.12%时,各组增重率和特定生长率均差异不显著。随着饲料蛋白质水平的增加,蛋白质效率逐渐降低。低蛋白质水平处理组（30.24%、33.22%、39.33%、42.15%）蛋白质沉积率显著高于48.12%处理组。蛋白质水平为42.15%时,饲料系数、全鱼水分达最小值,粗蛋白水平达最大值；血清胆固醇在饲料蛋白质水平为48.12%时最低,显著低于饲料蛋白质水平30.24%～39.33%处理组；血清甘油三酯在饲料蛋白质水平39.33%～48.12%处理组显著低于蛋白质水平30.24%～33.22%处理组。各试验组成活率、粗脂肪、血清总蛋白、球蛋白、碱性磷酸酶、谷丙转氨酶和谷草转氨酶均差异不显著。以饲料中蛋白质水平为自变量（x）,分别以增重率和饲料系数为因变量（y）进行二次曲线回归,得出增重率在最大值时,蛋白质的添加水平为43.09%,饲料系数为最小值时,饲料蛋白质水平为44.15%。

This study was conducted to determine the dietary protein requirement for young Barbus capito by formulating diets with seven protein levels of 30.24%,33.22%,36.23%,39.33%,42.15%, 45.33%and 48.12%.Each diet was randomly assigned to triplicates with 30fish each.Fish with initial body weight of（11.07±2.42）g were raised in recirculation system（each aquarium 220L）for 56dwith water flow rate of 2L/min.The results showed that weight gain and specific growth rate increased with the increasing protein level from 30.24%to 42.15%,but had no difference with each other when protein level ranged from 42.15%to 48.12%.Protein efficiency rate declined gradually with the increasing dietary protein level.Protein retention efficiency in 30.24%,33.22%,39.33% and 42.15% protein level groups was significantly higher than that of 48.12%protein group（P0.05）.Feed conversion efficiency and crude protein of body reached the maximum value,and moisture of body reached the minimum value in 42.15% protein group.Serum cholesterol reached the minimum value in 48.12% protein group and was significantly lower than that of groups with dietary protein ranged from 30.24% to 39.33%（P0.05）.Serum triglyceride in groups with protein ranged from 39.13%to 48.12% was significantly lower than that of groups with protein ranged from 30.24% to 33.22%（P0.05）.There were no difference in survival rate,crude lipid,serum total protein,globulin,alkaline phosphatase,alanine transaminase and aspartate aminotransferase（P0.05）.The weight gain and feed conversion efficiency reached the maximum value in 43.09%and 44.15% protein group respectively by using the polynomial regression model.