杂交鲌“先锋1号”幼鱼蛋白质需求量的研究

Dietary Protein Requirement of Juvenile Erythroculter ilishaeformis(♀) ×Ancherythroculter nigrocauda(♂) Hybrid F_1

本试验旨在研究饲料蛋白质水平对杂交鲌"先锋1号"幼鱼生长性能、体成分、血清生化指标及消化酶活性的影响,以确定其对蛋白质的需求量。以鱼粉、酪蛋白和明胶为蛋白质源,配制6种蛋白质水平(25.63%、30.28%、35.13%、40.26%、45.42%和50.53%)的等脂等能试验饲料。将平均体重为(5.42±0.16) g的杂交鲌"先锋1号"幼鱼630尾,随机分为6组,每组3个重复,每个重复放养35尾,在室内循环水养殖系统中进行56 d的养殖试验。结果表明:1)随着饲料蛋白质水平的升高,试验鱼的增重率和特定生长率先显著上升(P<0.05),在饲料蛋白质水平达到35.13%后趋于稳定;饲料系数呈下降趋势,40.26%组最低,且显著低于前3组(P<0.05);蛋白质效率和蛋白质沉积率均在50.53%组最低,且显著低于前4组(P<0.05)。2)饲料蛋白质水平对幼鱼全鱼水分和粗灰分含量没有显著影响(P>0.05),但显著影响了全鱼粗蛋白质和粗脂肪的含量(P<0.05)。40.26%、45.42%和50.53%组的全鱼粗蛋白质含量均显著高于25.63%组(P<0.05);全鱼粗脂肪含量随着饲料蛋白质水平的升高呈下降趋势,50.53%组最低,显著低于前5组(P<0.05)。3)饲料蛋白质水平对血清总胆固醇和甘油三酯含量无显著影响(P>0.05)。血清总蛋白含量随着饲料蛋白质水平的升高呈先升高后下降的趋势,在40.26%组最高,且显著高于其余各组(P<0.05); 45.42%组血清谷草转氨酶活性最高,显著高于除了40.26%组之外的其余4组(P<0.05);血清谷丙转氨酶活性先上升后稳定,45.42%和50.53%组显著高于其余各组(P<0.05)。4)饲料蛋白质水平对试验鱼肠道和肝脏的蛋白酶和淀粉酶活性有显著影响(P<0.05),对脂肪酶活性无显著影响(P>0.05)。以增重率和蛋白质效率为评价指标,通过折线回归分析得到杂交鲌"先锋1号"幼鱼对饲料蛋白质的需求量分别为36.43%和38.81%。

This experiment was conducted to investigate the effects of dietary protein level on growth performance,whole body composition,serum biochemical indexes and digestive enzyme activities of juvenile Erythroculter ilishaeformis(♀)×Ancherythroculter nigrocauda(♂)hybrid F1.Fish meal,casein and glutin were used as the protein sources to formulate 6 experimental diets containing different protein levels of 25.63%,30.28%,35.13%,40.26%,45.42%and 50.53%,respectively.A total of 630 juvenile hybrid F1 with an average body weight of(5.42±0.16)g were randomly assigned to 6 groups with 3 replicates per group and 35 fish per replicate.The experiment lasted for 56 d.The results showed as follow:1)the weight gain rate(WGR)and specific growth rate(SGR)of the juvenile hybrid F1 significantly increased as dietary protein level increasing(P<0.05),and then tended to stabilize when protein level was 35.13%.The feed conversion ratio(FCR)showed a decrease trend,and the FCR in 40.26%group was the lowest,and significantly lower than that in the first three groups(P<0.05).Protein efficiency ratio(PER)and protein productive value(PPV)in 50.53%group were the lowest,and significantly lower than those in the first four groups(P<0.05).2)The dietary protein level did not significantly affect the whole-body moisture and ash contents(P >0.05),but significantly affected the crude protein and crude lipid contents(P<0.05).Body protein contents in 40.26%,45.42%and 50.53%groups were significantly higher than those in 25.63%group(P<0.05),while the crude lipid content trended to decrease as the dietary protein level increasing.The lipid content in 50.53%group was the lowest,and significantly lower than that in other groups(P<0.05).3)There were no significant differences in triglyceride(TG)and total cholesterol(TCHO)contents in serum among all groups(P >0.05).Serum total protein(TP)content trended to increase first and then decrease with increasing dietary protein level,that in 40.26%group was the highest,and significanlty higher than that in other groups(P<0.05).Serum aspartate aminotransferase(AST)activity in 45.24%group was the highest,and significantly higher than that in other groups except 40.26%group(P<0.05).Serum alanine aminotransferase(ALT)activity was increased initially,and then reached a plateau with increasing dietary protein level.The values in 45.42%and 50.53%groups were significantly higher than those in other groups(P<0.05).4)The protease and amylase activities in the intestine and liver significantly affected by dietary protein level(P<0.05).While the lipase activities in the intestine and liver did not significantly affected by dietary protein level(P >0.05).Broken-line regression analysis shows that the optimal requirement of dietary protein for juvenile hybrid F1,using WGR and PPV as a response criteria,are 36.43%and 38.81%,respectively.