养成期斜带石斑鱼对饲料脂肪的需要量

Dietary lipid requirement of grow-out grouper(Epinephelus coioides)

在基础饲料中添加鱼油,配成5种不同脂肪水平(7.07%、9.92%、12.92%、15.95%和19.04%)的等氮饲料,投喂体重278.5 g的石斑鱼10周。结果表明:随着饲料脂肪水平的升高,石斑鱼的增重率、特定生长率和蛋白质效率呈逐渐上升后显著下降趋势(P<0.05),饲料效率变化趋势同增重率相反;各处理组成活率不受饲料脂肪水平的影响(P>0.05)。全鱼和肌肉粗脂肪含量逐渐上升后稳定,全鱼灰分含量逐渐下降;全鱼水分、粗蛋白和肌肉水分、粗蛋白、灰分含量不受饲料脂肪水平的影响(P>0.05)。肥满度和脏体比随饲料脂肪水平的增加逐渐上升后稳定;肝体比逐渐上升。血浆葡萄糖、甘油三酯、总胆固醇和高密度脂蛋白水平均显著升高(P<0.05),总蛋白和低密度脂蛋白显著下降(P<0.05)。肝脏肝酯酶、脂蛋白酯酶和苹果酸脱氢酶活力随饲料脂肪水平的升高逐渐下降,乳酸脱氢酶活力逐渐上升。肝脏碱性磷酸酶、超氧化物歧化酶和溶菌酶活力随饲料脂肪水平的升高逐渐上升后稳定;酸性磷酸酶活力显著下降(P<0.05)。以特定生长率为判据,二次曲线模型拟合得出,养成期斜带石斑鱼对饲料脂肪的需要量为14.44%。

The present study was performed to investigate the requirement of lipid for grow-out grouper. Fish （initial body weight 278.5 g） were fed isonitrogenous diets containing five graded lipid levels （7.07%, 9.92% ,12.92% ,15.95% and 19.04% ） of fish oil and soybean lecithin for 10 weeks. The results showed that： Weight gain rate, specific growth rate and protein efficiency ratio significantly increased, then decreased （P 〈0.05） with increased dietary lipid levels. Feed conversion ratio showed an opposite trend with weight gain rate. Survival of treatments were not significantly affected by the dietary lipid levels （ P 〉 0.05 ）. Whole body and muscle crude lipid content first gradually increased, then stabilized and whole body ash gradually decreased with the dietary lipid level increased. Moisture and crude protein in whole body and moisture, crude protein and ash in muscle were not affected by dietary lipid levels （P 〉 0.05 ）. With increased dietary lipid levels, condition factor and viscerosomatic index gradually increased and then stabilized and hepatosomatic index gradually increased. Plasma glucose, triglyceride, total cholesterol and high density lipoprotein cholesterol levels significantly increased with increased dietary lipid levels （P 〈 0.05 ）, and total protein, low density lipoprotein cholesterol decreased significantly （P 〈 0.05 ）. With increased dietary lipid levels, the hepatic lipase, lipoproteinesterase and malic dehydrogenase activity gradually decreased, but lactate dehydrogenase activity gradually increased. Alkaline phosphatase, superoxide dismutase, lysozyme activities first increased, then stabilized with increased dietary lipid levels and acid phosphatase vitality significantly decreased （P 〈 0.05 ）. On the basis of specific growth rate, the optimum dietary lipid level, determined by second-order polynomial regression analysis is 14.44% for grow-out Epinephelus coioides.