斜带石斑鱼幼鱼的饲料精氨酸需求量

Requirement of dietary arginine for juvenile orange-spotted grouper, Epinephelus coioides

通过配制7种含不同水平精氨酸(2.13%、2.42%、2.71%、2.95%、3.20%、3.48%、3.74%干物质)的等氮、等脂的实验饲料,研究精氨酸对斜带石斑鱼(Epinephelus coioides)幼鱼生长、饲料利用和血清一氧化氮合酶等的影响。每组设3个重复,每个重复30尾鱼(7.52±0.02g),饲喂8周。结果显示,饲料精氨酸水平对各组存活率无显著影响(P>0.05);精氨酸水平为2.95%的斜带石斑鱼获得最大增重率和特定生长率,显著高于其他各组(P<0.05);2.95%组饲料系数显著低于2.13%、2.42%和2.71%组(P<0.05);3.20%组体蛋白达到最大,显著高于2.13%组(P<0.05)。随着饲料中精氨酸水平的增加,斜带石斑鱼幼鱼血糖含量呈逐渐降低的趋势,2.13%与2.42%组显著高于其他各组(P<0.05)。2.95%组血清总蛋白和血清总一氧化氮合酶显著高于其他各组(P<0.05)。研究表明,日粮中适宜的精氨酸水平不仅能促进斜带石斑鱼幼鱼生长和体蛋白的合成,还能提高机体免疫力。以特定生长率为判据,通过二次多项式回归分析表明,斜带石斑鱼幼鱼精氨酸的最适需要量是饲料干重的3.06%(饲料蛋白含量的6.07%)。

Seven isonitrogenous and isolipidic commercial diets with arginine contents of 2.13%, 2.42%, 2.71%, 2.95%, 3.20%, 3.48%, or 3.74%（dry matter） were formulated to investigate the effects of dietary arginine on growth performance, feed utilization, and serum total nitric oxide synthase in the juvenile orange-spotted grouper, Epinephelus coioides. Triplicate groups of 30 fish with mean body weight of （7.52±0.02） g were randomly assigned to each treatment in separate tanks. The fish were fed the experimental diets for 8 weeks. The different levels of dietary arginine had no significant effect on the fish survival rate （P〉0.05）. However, the weight gain rate and specific growth rate were significantly higher in the 2.95% arginine group than in the other groups （P〈0.05）. The feed coefficient of the fish fed 2.95% arginine was significantly lower than that of the fish fed 2.13%, 2.42%, or 2.71% arginine （P〈0.05）. The whole-body protein of the fish fed 3.20% arginine was signifi- cantly higher than that of the fish fed 2.13% arginine （P〈0.05）. Serum glucose tended to decrease as dietary ar- ginine increased, and was significantly higher in the fish fed 2.13% or 2.42% arginine than in those of the other groups （P〈0.05）. Total protein and total nitric oxide synthase were significantly higher in the sera of fish fed 2.95% arginine than those in the sera of fish in the other groups （P〈0.05）. These results indicate that dietary arginine not only promotes growth and body protein synthesis, but also improves the immunity of the grouper. A quadratic regression analysis of the specific growth rate against dietary arginine indicated that the optimum argin- ine level for the maximum growth of the juvenile grouper is 3.06%, corresponding to 6.07% of dietary protein on a dry weight basis.