饲料蛋白水平对鲈鱼生长、体组成及蛋白酶活力的影响

以初始体重为(34.15±0.33)g的鲈鱼Lateolabrax japonicus为研究对象,鱼粉和酪蛋白作为蛋白源,设计并制成蛋白质梯度分别为35%、40%、45%、50%、55%的5组配合饲料,进行为期56 d的生长试验,探讨配合饲料中不同蛋白质水平对鲈鱼生长、体组成及蛋白酶活力的影响。结果表明,各组鲈鱼存活率为91.7%-96.7%,无显著差异(P0.05);随着饲料蛋白质水平的提高,鲈鱼的特定生长率逐渐升高,当饲料蛋白质水平达到45%时趋于稳定,且饲料蛋白45%、50%、55%组试验的特定生长率显著高于35%组(P0.05);蛋白质沉积率呈先上升后下降的趋势,当饲料蛋白质水平达到45%时达到最大值;饲料蛋白质水平对鲈鱼鱼体水分含量无显著性影响(P0.05),鲈鱼鱼体粗蛋白含量随着饲料蛋白水平提高而增加,粗灰分、粗脂肪含量则呈减少趋势;随饲料蛋白质水平提高,胃蛋白酶和胰蛋白酶的活性呈升高趋势,肝脏组织中谷草转氨酶的活性呈现升高趋势,而谷丙转氨酶的活性没有显著性变化(P0.05)。饲料中蛋白水平为45.00%-45.89%,其生长及蛋白沉积率最高。

Impact of dietary protein level on growth performance, body composition and protease activity of juvenile Lateolabrax japonicus

An eight-week experiment was conducted to investigate the effects of dietary protein level on the growth performance,body composition,and protease activity of Japanese seabass Lateolabrax japonicus at average weight of （34.15 ± 0.33） g.Fish meal and casein were used as the main dietary protein,and five diets containing 35%,40%,45%,50% and 55% protein were prepared.Feed experiment on the Japanese seabass showed no significant difference in survival rate （91.7%-96.7%） among dietary treatments （P 〉 0.05）.As the dietary protein level increased,the specific growth rate （SGR） increased.Diets at protein level of 45%,50%,and 55% obtained significantly higher SGR than the diet with 35% protein （P 〈0.05）.The protein productive value （PPV） of fish fed diet with 45% protein was significantly higher than that of other groups.In the experiment,with the increase of dietary protein level,the content of crude protein of whole body increased,but the crude fat and ash decreased.There was no significant difference in whole body moisture content among all groups （P 〉 0.05）.As dietary protein increased,activities of pepsin,trypsin and glutamic-oxaloacetic transaminase （GOT） increased significantly （P 〈 0.05）,but for activity of glutamic-pyruvic transaminase （GPT）,there was no significant differences among all groups（P 〉 0.05）.The optimal dietary protein level of Japanese seabass was 45.00%-45.89%.