乌苏里拟鲿稚鱼饲料中蛋白质的适宜水平

Optimum Dietary Protein Level of Juvenile Pseudobagrus ussuriensis

本试验采用鱼粉、酪蛋白和玉米蛋白粉为蛋白质源,配制蛋白质水平分别为35%、40%、45%和50%的4种等能饲料,以确定乌苏里拟鲿稚鱼饲料中蛋白质的适宜水平。试验选用乌苏里拟鲿稚鱼[初始体重为(3.40±0.01)g]300尾,随机分为4组,每组设3个重复,每个重复25尾鱼。试验期为8周。结果表明:45%组乌苏里拟鲿稚鱼的增重率和特定生长率显著高于35%和40%组(P<0.05),但与50%组差异不显著(P>0.05);而饲料系数则表现出相反的变化趋势。随着饲料蛋白质水平从35%升高到50%,乌苏里拟鲿稚鱼的蛋白质效率显著降低(P<0.05)。饲料蛋白质水平对乌苏里拟鲿稚鱼全鱼和肌肉水分以及全鱼灰分含量无显著影响(P>0.05)。45%组乌苏里拟鲿稚鱼的全鱼和肌肉粗蛋白质含量显著高于35%和40%组(P<0.05)。随着饲料蛋白质水平的升高,乌苏里拟鲿稚鱼的全鱼粗脂肪含量呈先增加后降低趋势,而肌肉粗脂肪和灰分含量则呈降低趋势。各组乌苏里拟鲿稚鱼的肥满度、肝胰指数和内脏指数无显著差异(P>0.05)。在本试验条件下,以增重率和饲料系数为指标,乌苏里拟鲿稚鱼饲料中蛋白质的适宜水平为45%。

This study was conducted to determine the optimum dietary protein level of juvenile Pseudobagrus ussuriensis.Four isoenergetic diets were formulated with fish meal,casein and corn gluten meal as protein sources containing graded levels of protein: 35%,40%,45% and 50%,respectively.A total of 300 juvenile Pseudobagrus ussuriensis with an initial body weight of(3.40±0.01) g were randomly divided into 4 groups with 3 replicates per group and 25 fish per replicate.The experiment lasted for 8 weeks.The results showed as follows: the weight gain rate and specific growth rate of juvenile Pseudobagrus ussuriensis in 45% group were significantly higher than those in 30% and 40% groups(P<0.05),but there were no significant differences between the 45% and 50% groups(P>0.05);however,the feed conversion ratio showed an opposite trend.With increasing dietary protein level from 35% to 50%,the protein efficiency ratio was significantly decreased(P<0.05).The moisture and ash contents in whole fish and moisture content in muscle of juvenile Pseudobagrus ussuriensis were not significantly affected by dietary protein level(P>0.05).The crude protein content in whole fish and muscle of juvenile Pseudobagrus ussuriensis in 45% group was significantly higher than that in 30% and 40% groups(P<0.05).With increasing dietary protein level,the crude lipid content in whole fish of juvenile Pseudobagrus ussuriensis was firstly increased and then decreased,while the crude lipid and ash contents in muscle were decreased.No significant differences were found in condition factor,hepaticsomatic index and viscerosomatic index of juvenile Pseudobagrus ussuriensis among all groups(P>0.05).In this experiment,based on the indices of weight gain rate and feed conversion ratio,the optimum dietary protein level of juvenile Pseudobagrus ussuriensis is 45%.