饲料中不同蛋白含量对斑节对虾幼虾生长及消化酶的影响

Effects of dietary protein content on growth performance and digestive enzyme activities of black tiger shrimp,Penaeus monodon

选用鱼粉、豆粕和大豆浓缩蛋白为主要蛋白源,配置6个蛋白质水平梯度(36%、38%、40%、42%、44%、46%)的饲料,对斑节对虾幼虾(1.03±0.02 g)进行56 d养殖实验,研究饲料中不同蛋白含量对斑节对虾幼虾生长及消化酶活性的影响。结果表明,(1)摄食40%蛋白饲料的斑节对虾的增重率(417.35%)和特定生长率(2.93%·d-1)获得最大值并显著高于36%蛋白饲料组(P<0.05),但与其它各组无显著差异。饲料蛋白水平在38%时的饲料系数(1.88)最低且与44%和46%蛋白饲料组存在显著性差异(P<0.05)。(2)虾体蛋白含量在44%饲料蛋白组最高,且显著高于36%、38%和42%组(P<0.05)。(3)斑节对虾的蛋白质表观消化率在42%蛋白组最高,44%和46%蛋白饲料组的蛋白质效率显著低于36%～42%蛋白饲料组(P<0.05)。(4)随着蛋白水平的提高,斑节对虾的蛋白酶活性呈现由高到低波动的趋势;淀粉酶活性随着饲料蛋白含量的升高而呈下降趋势,胃淀粉酶活性在38%～42%蛋白饲料组显著高于36%蛋白饲料组(P<0.05),肠淀粉酶活性在42%蛋白饲料组显著高于其它各组(P<0.05)。通过饲料中蛋白质含量与增重率的回归分析,斑节对虾幼虾饲料蛋白的适宜含量为39.70%。

A 56-day feeding trial was conducted to study the effects of six dietary protein content(36%,38%,40%,42%,44%,46%) on growth performance(weight gain,WG;specific growth rate,SGR;survival rate,SR) and digestive enzyme activities(protease and amylase activities of hepatopancreas,stomach and intestine) of Penaeus monodon.The triplicate feeding trials were conducted in tanks indoor,and 30 prawns(initial mean weight: 1.03±0.02 g)were randomly stocked in each of eighteen 500 L tanks.The results showed that WG and SGR increased with the increasing dietary protein content,WG and SGR of shrimp fed with 40% dietary protein were significantly higher than that of shrimp fed with 36% dietary protein(P<0.05),but showed no significant differences with other dietary proteins(P>0.05).The maximal WG and SGR were found in 40% group(WGmax=417.35%,SGRmax=2.93%·d-1).When the protein level was 38%,the feed conversion rate was the lowest and significantly lower than that of shrimp fed with 44% and 46%(P<0.05).Body protein content of shrimp fed with 44% dietary protein was the highest and significantly different from that of shrimp fed with 36%,38% and 42% dietary protein(P<0.05).The apparent protein digestibility of shrimp fed with 42% dietary protein was significantly higher than that of shrimp fed with 46% dietary protein(P<0.05),but showed no significant differences with other dietary protein(P>0.05).Shrimp fed with high protein diets(44%,46%) had significantly lower PER values than shrimp fed with lower protein diets(36%-42%)(P<0.05).The proteinase activities in hepatopancreas,stomach and intestine fluctuated from high to low with the increasing of the dietary protein content.The amylase activities decreased with the increasing of the dietary protein levels.Stomach amylase activities of shrimp fed with 38%-42% dietary protein were significantly higher than that of shrimp fed with 36% dietary protein(P<0.05).Intestine amylase activity of shrimp fed with 40% dietary protein was significantly higher than that of shrimp fed with other dietary protein levels(P<0.05).Based on the regression of WG to dietary protein content,the optimal dietary protein requirement for juvenile P.monodon was 39.70%.