饲料蛋白质水平对大刺鳅幼鱼生长性能、消化酶和肝转氨酶活性的影响

Effects of dietary protein levels on growth performance, digestive enzyme and liver transaminase activities of juvenile Mastacembelus aculeatus

采用60 d的单因素饲养试验,探讨饲料蛋白质水平分别为35%、38%、41%、44%、47%、50%、53%对体质量为(5.21±0.15)g的大刺鳅(Mastacembelus aculeatus)幼鱼生长性能、消化酶和肝转氨酶活性的影响,以探明大刺鳅幼鱼配合饲料适宜蛋白质水平。试验结果表明:饲料蛋白质水平对大刺鳅幼鱼存活率的影响不显著(P>0.05)。与35%~38%蛋白质组相比,当饲料蛋白质水平为50%时,大刺鳅幼鱼增重率、特定生长率和蛋白质效率获得最大值,饲料系数获得最小值,分别为116.7%、1.55%/d、203.29%和0.99,差异显著(P<0.05)。随蛋白质水平升高,大刺鳅幼鱼胃蛋白酶、肠道胰蛋白酶及淀粉酶呈先上升后平稳趋势,50%蛋白质组的酶活性最高,为14.49、4 374.67 U/mg prot.和1.02 U/mg prot.。肝脏胰蛋白酶及淀粉酶活性分别在50%、53%蛋白质组达到最高,与35%~41%蛋白质组显著差异(P<0.05),谷丙转氨酶及谷草转氨酶均随饲料蛋白质水平的增加而升高,表明大刺鳅幼鱼体内蛋白质代谢活力随饲料蛋白质水平升高而增强,鱼体对蛋白质及氨基酸的利用率有一定提高。通过饲料中蛋白质含量与生长速率指标的回归分析,大刺鳅幼鱼饲料蛋白质的适宜含量为50.7%~52.5%。

A 60-day feeding test was conducted to investigate the effects of dietary protein levels （35%, 38%, 41%, 44%, 47%, 50% and 53%） on growth performance, digestive enzymes and transaminase activities in liver of juvenile Mastacembelus aculeatus [body weight （5.21±0.15） g]. The results showed the survival rate was not significantly affected by the dietary protein levels（P〉0.05）. The weight gain rate （WGR）, special growth rate （SGR） and protein efficiency rate （PER） of juvenile Masta- eembelus aeuleatus reached the maximum values at 116.7%, 1.55%/d, 203.29% when dietary protein levels was 50%, while the feed conversion rate was significant decreased to 0.99 （P〈0.05） compared to 35%-38% protein group. The activitis of pepsin, trypsin and amylase in intestinal of jurenile Mastacembelus aculeatus were increased and then steady with dietary protein level increasing, each value were the highest （14.49, 4 374.67 U/mg prot. and 1.02 U/mg prot. respectively） in 50% group. The proteases （trypsin, amylase） activitis in liver was significantly affected by the dietary protein levels （P〈O.05）, and the highest value showed on protein level of 50% and 53% group respectively. Both alanine and aspartate transaminase increased with the increment of feed protein level, which indicated that the protein metabolic activity of juvenile Mastacembelus aculeatus was enhanced and the utilization of protein and amino acid improved. With WGR and SGR as an evaluating index, the optimal dietary protein requirement estimated by broken-line model is 50.7%-52.5% for juvenile Mastacembelus aculeatus.