低蛋白质饲料中添加色氨酸对凡纳滨对虾生长性能、体组成、血清免疫和抗氧化指标的影响

Effects of Low Protein Diet Supplemented with Tryptophan on Growth Performance,Body Composition,Immunity and Antioxidant Functions in Serum of Litopenaeus vannamei

本试验旨在研究低蛋白质饲料中添加色氨酸对凡纳滨对虾生长性能、体组成、血清免疫和抗氧化指标的影响。试验选取初始体重为(2.00±0.01)g的凡纳滨对虾960尾,随机分成6组(HT0、LT0、LT1、LT2、LT3、LT4),每组4个重复,每个重复40尾虾。HT0、LT0、LT1、LT2、LT3、LT4对虾分别投喂含40.79%粗蛋白质的高蛋白质饲料,以及含37.01%粗蛋白质并分别添加0、1.20、2.50、5.00和10.00g/kg色氨酸的低蛋白质饲料,试验期为8周。结果表明:LT2、LT3对虾的终末体重、增重率和特定生长率显著高于HT0(P<0.05);LT1、LT2、LT3的摄食量显著高于HT0和LT0(P<0.05);LT0、LT3、LT4的蛋白质效率显著高于HT0(P<0.05);饲料系数在HT0、LT0、LT3、LT4之间无显著差异(P>0.05);除LT1和LT3成活率较低外,其他组间无显著差异(P>0.05);与HT0和LT0相比,LT1、LT2、LT3、LT4肝胰指数、全虾水分和粗灰分含量均无显著变化(P>0.05)。全虾粗蛋白质含量LT2、LT3、LT4与HT0无显著差异(P>0.05),但LT4显著高于LT0和LT1(P<0.05);全虾粗脂肪含量LT0、LT2、LT3与HT0相比无显著差异(P>0.05),但LT1、LT4显著低于HT0(P<0.05)。对虾血清酚氧化酶、碱性磷酸酶、总超氧化物歧化酶活性及总抗氧化能力各组间均无显著差异(P>0.05);LT2血清过氧化氢酶活性显著高于LT0(P<0.05);LT2、LT3和LT4血清丙二醛含量均显著低于LT0(P<0.05),但与HT0相比无显著差异(P>0.05)。由此可见,在低蛋白质饲料中添加色氨酸可增加凡纳滨对虾的机体蛋白质沉积,增强对虾免疫和抗氧化能力,提高生长性能。本试验条件下,分别以增重率和血清过氧化氢酶活性为评价指标,通过回归方程得出含37.01%粗蛋白质的低蛋白质饲料中色氨酸的适宜含量分别为7.53和8.04g/kg。

This experiment was conducted to examine the effects of low protein diet supplemented with tryptophan on growth performance, body composition, immunity and antioxidant functions in serum of Litopenaeus vannamei. A total of 960 Litopenaeus vannamei with the average body weight of （ 2.00＋0.01 ） g were randomly allocated into 6 groups （ HT0, LT0, LT1 , LT2, LT3 and LT4 ） with 4 replicates per group and 40 shrimp per replicate. Shrimp in HT0 were fed a high protein diet with 40.79% crude protein, and Shrimp in LT0, LT1, LT2, LT3 and LT4 were fed low protein diets which contained 37.01% crude protein and supplemented with 0, 1.20, 2.50, 5.00 and 10.00 g/kg tryptophan, respectively. The feeding experiment lasted for 8 weeks. The results showed that the final body weight, weight gain rate, specific growth rate in LT2 and LT3 were significantly higher than those in HT0（P〈0.05） ; the feed intake in LT1, LT2 and LT3 was significantly higher than that in HT0 and LT0（P〈0.05） ; the protein efficiency ratio in LT0, LT3 and LT4 was significantly higher than that in HT0（P〈0.05） ; the feed conversion rate was found no significant difference among HT0, LT0, LT3 and LT4 （P〉0.05） ; the survival rate was lower in LT1 and LT3, but the other four groups showed no significant difference （P〉0.05） ; the hepatosomatic index, moisture and ash contents of whole-body in LT1, LT2, LT3 and LTa had no significant differences compared with HT0 and LT0（P〉0.05）. There was no significant difference in the whole-body crude protein content among LT2, LTz, LTa and HT0（P〉0.05） , however, LTa was significantly higher than LT0 and LT1（P〈0.05） ; the ether extract content of whole-body in LT1 and LT4 was significantly reduced compared with HT0（ P〈0.05）, while there no significant difference among LT0, LT2, LT3 and HTo（P〉0.05）. The activities of phenol oxidase, alkaline phosphatase and total superoxide dismutase, and total antioxidant capacity in serum had no significant differences among all the groups （P〉0.05） ; the serum catalase activity in LT2 was significantly higher than that in LT0 （P〈0.05） ; the serum malonaldehyde content in LT2, LT3 and LT4 was significantly lower than that in LT0（P〈0.05） , but it in LT2, LT3 and LT4 showed no significant difference compared with HT0（P〉0.05）. In conclusion, tryptophan supplemented in the low protein diets can increase the whole-body protein deposition, improve the immunity and antioxidant functions, and enhance the growth performance. Regression analysis base on weight gain rate and serum catalase activity indicates that the optimal dietary tryptophan content in low protein diet （37.01% crude protein） for L. vannamei is 7.53 and 8.04 g/kg, respectively.