饲料蛋白水平对日本沼虾生长、消化酶和免疫酶的影响

Effects of Dietary Protein Levels on Growth,Digestive Enzyme Activities and Immune Enzyme Activities of Macrobrachium nipponense

按等能量不等蛋白的原则，配制蛋白水平分别为28％、32％、36％、40％、44％的5组饲料投喂日本沼虾[体重（0．28±0．07）g]。饲养52d时测定虾的增重率、饲料系数、成活率、消化酶活性和免疫酶活性等指标。结果显示：投喂不同蛋白质水平饲料的各组日本沼虾之间，增重率、饲料系数、成活率和肝胰腺中蛋白酶活性有显著差异（P〈0．05）；当饲料蛋白水平为40％时，日本沼虾的成活率和增重率最高，饲料系数最小；肝胰腺中蛋白酶活性随饲料蛋白水平的增加而增加，但当饮料蛋白水平超过36％时胃蛋白酶活性下降，当饲料蛋白水平超过40％时类胰蛋白酶活性下降；胃中蛋白酶有随饲料蛋白水平增加而上升的趋势，但饲料不同蛋白水平对其影响差异不显著（P〉0．05）；饲料不同蛋白水平对ACP酶活性的影响有显著差异（P〈0．05），但对AKP、SOD酶活性影响的差异不显著（P〉0．05）。以增重率为指标，采用直线回归法，拟合出线性方程Y=0．3548x＋46．3380。采用抛物线回归法，拟合出抛物线方程Y=-0．0771x^2＋5．9691x-53．4200。由两个回归方程计算出日本沼虾饲料中的最适蛋白质含量为38．7％～40．3％。结合饲料系数、消化酶活性和免疫酶活性等指标的考察，建议在日本沼虾生产中，中期配合饲料的适宜蛋白质水平为38．7％～40．3％。

Five groups of diets containing different protein contents, 28% ,32% ,36% ,40% and 44% , were fed to Macrobrachium nipponense, mean initial weight of （0. 28 ±0. 07） g. After 52-day feeding,the weight gain rate, feed conversion ratio, survival rate and digestive enzyme activities as well as immune enzyme activities were determined. The dietary protein levels significantly affected the weight gain rate, feed conversion ratio, survival rate and the protease activity in the hepatopancreas （P 〈 0. 05 ）. Those fed with the diet containing 40% protein showed the highest weight gain rate, survival rate and the lowest feed conversion ratio. The protease activity in the hepatopancreas was enhanced with the increase in dietary protein levels,but the activity of pepsin was decreased as the dietary protein level was above 36% and the activity of trypsin-like enzyme was decreased as the dietary protein level was above 40%. The protease activity in the stomach tended to ascend with the increase in dietary protein levels. The dietary protein levels had significant effects on the activity of ACP in the hepatopancreas （ P 〈 0. 05 ）. For the activities of AKP and SOD in the hepatopancreas, the effects were insignificant （P 〉 0.05）. According to the linear regressive equation Y = 0. 354 8x ＋ 46. 338 0 and parabola regressive equation Y = -0. 077 1x^2 ＋ 5. 969 1x - 53.420 0 （ Y： weight gain rate,x： protein content） obtained in the experiment,the protein requirement of Macrobrachium nipponense was estimated to be 38.7% -40. 3%. Based onthe performance of the weight gain rate, feed conversion ratio,digestive enzyme activities and immune enzyme activities, it was reasonable to recommend 38.7% -40. 3% as the optimum protein level in the diet for sub-adult Macrobrachium nipponense.