饲料蛋白质和能量水平对草鱼幼鱼生长和消化酶活性的影响

在水温24～29℃下,将675尾规格整齐、健康、体质量为（35.59士0.44）g的草鱼（Ctenopharyngodon idel-lus）随机分为9个处理,每处理3个重复,放养于水泥池中的网箱（100cm×50cm×100cm）内,投喂以鱼粉和豆粕为蛋白源,豆油作为脂肪源配制的3个蛋白水平（24%、28%、32%）,每一蛋白水平设3个脂肪水平（4%、6%、8%）,共计9种饲料。饲料蛋能比（P/E）在15.81-22.46 mg·kJ-1之间。92d的饲养表明：D4组（蛋白质含量为28.02%,脂肪为4.30%）草鱼的特定生长率最高,显著高于其他各组（P〈0.05）。随着饲料中蛋白含量的增加,草鱼全肠中蛋白酶的活力逐渐升高,之后又降低,以D4组饲料的蛋白酶活性最高,显著高于D1、D8和D9（P〈0.05）。本实验表明,该生长阶段的草鱼所需最适蛋白水平为28.02%,能量为14307kJ.kg-1,P/E约为19.58mg·kJ-1。

Effects of Dietary Protein and Lipid Levels on Growth,Body Composition and Digestive Enzyme Activity in Juvenile Grass Carp Ctenopharyngodon idellus

Six hundred and seventy five grass carp（Ctenopharyngodon idellus）juveniles（body weight 35.59 ±0.44g）were randomly divided into nine groups with triplication,stocked into net cages displaced in an indoor tank and fed one of the nine diets containing three protein levels（24%,28% and 32%,fishmeal and soybean meal as dietary protein）and three lipid levels（4%,6% and 8%,soybean oil as dietary lipid）for 92 days to evaluate the effects of dietary protein and lipid levels on the growth performance and digestive enzyme activities of grass carp.The results showed that specific growth rate was found significantly higher in the fish fed the diet D4（containing 28.02% protein,and 4.30% fat）than that in the fish fed the other diets（P＆lt; 0.05）.There was significantly higher proteinase activity in the fish fed the diet D4 than those in the fish fed diets D1,D8 and D9（P＆lt; 0.05）.It is recommended that the optimal ratio of protein level to energy（P/E）be 28.02/19.58,optimal dietary proten level 28.02% and optimal energy 14307 kJ.kg-1,for grass carp juveniles.