低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活和全虾氨基酸组成的影响

研究旨在探讨低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活以及全虾氨基酸组成的影响。试验选取初始体重为(2.000.01) g对虾960尾, 随机分成6组, 每组4个重复。各组分别投喂含40.79%粗蛋白质的高蛋白基础饲料(HT0)、含37.01%粗蛋白质的低蛋白基础饲料并添加0 (LT0)、1.20(LT1)、2.50 (LT2)、5.00 (LT3)和10.00 (LT4)g/kg色氨酸的6种饲料。饲养56d后采样、分析蛋白酶活和全虾氨基酸组成; 在此基础上投喂含0.04%三氧化二钇(Y2O3)的相应饲料进行消化率试验。结果表明:低蛋白质饲料中添加色氨酸可提高对虾蛋白质、氨基酸、干物质、能量的表观消化率, 蛋白酶活和影响全虾氨基酸组成(P0.05)。LT3、LT4粗蛋白质表观消化率显著高于LT0(P0.05)。LT3蛋氨酸表观消化率显著高于LT0, LT3酪氨酸表观消化率显著高于HT0 (P0.05)。LT3和LT4干物质表观消化率显著高于LT0 (P0.05)。LT1、LT2、LT3和LT4总能表观消化率均高于LT0, 但仅LT4达显著水平(P0.05)。LT2肠蛋白酶活最高, 并显著高于HT0和LT1 (P0.05), LT2、LT3、LT4肝胰腺蛋白酶活显著高于LT0 (P0.05), 但与HT0相比无明显差异(P0.05)。LT4全虾天门冬氨酸、甘氨酸、丙氨酸、蛋氨酸、亮氨酸含量均明显高于LT0 (P0.05)。LT1全虾赖氨酸含量显著高于LT0 (P0.05)。由此可见, 低蛋白质饲料中添加色氨酸可明显提高凡纳滨对虾饲料蛋白质、氨基酸、干物质和能量的表观消化率、蛋白酶活, 并改善全虾氨基酸的组成。

EFFECTS OF TRYPTOPHAN SUPPLEMENTED IN LOW PROTEIN DIETS ON APPARENT DIGESTIBILITY COEFFICIENTS,DIGESTIVE ENZYME ACTIVITY AND AMINO ACIDS COMPOSITION OF LITOPENAEUS VANNAMEI

To examine effects of L-tryptophan supplemented in low protein diets on apparent digestibility coefficients, digestive enzyme activity and amino acids composition of the whole body in Litopenaeus.vannamei, six diets including high protein diet with 40.79%crude protein (HT0), and low protein diets with 37.01%crude protein supplemented with 0 (LT0), 1.20 (LT1), 2.50 (LT2), 5.0 (LT3) and 10.0 (LT4) g/kg L-tryptophan were formulated to feed 960 shrimp with the average body weight of (2.00±0.01) g that were randomly allocated into 6 groups with 4 replicates for a 56-day ex-periment. The results showed that tryptophan supplemented in low protein diets significantly increased the apparent di-gestibility coefficients (ADCs) of crude protein (CP) and amino acids, dry matter (DM), gross energy (GE), protease activity, and the body amino acids composition (P<0.05). The ADCs of CP in LT3 and LT4 were significantly higher than that of LT0 (P<0.05). The ADCs of methionine in LT3 was significantly higher than that of LT0 (P<0.05). The ADCs of tyrosine in LT3 was significantly higher than that of HT0 (P<0.05). The ADCs of DM in LT3 and LT4 were significantly higher than that of LT0 (P<0.05). The ADCs of GE in LT1, LT2, LT3 and LT4 were higher than that of LT0, and the ADCs of GE in LT4 significantly higher than that of LT0 (P<0.05). The addition of L-tryptophan signifi-cantly increased the intestine protease activity, and LT2 was the highest group. The hepatopancreas protease activity in LT2, LT3 and LT4 were significantly higher than that of LT0 (P<0.05), but there was no significant difference com-pared to HT0 (P>0.05). Aspartic acid, glycin, alanine, methionine and leucine content of the shrimp in LT4 was signifi-cantly higher than that of LT0 (P<0.05), and lysine content of the shrimp in LT2 were significantly higher than that of LT1 (P<0.05). In conclusion, L-tryptophan supplemented in low protein diets could enhance the ADCs of CP, amino acids, DM, GE, the protease activity, as well as improve the shrimp body amino acids composition.