饲料中添加赖氨酸甲酯对草鱼生长相关指标的影响

Effects of dietary supplementation of lysine methyl ester on growth performance in grass carp Ctenopharyngodon idella

选择健康草鱼Ctenopharyngodon idella360尾(始重8.34 g±0.02 g),按照养殖试验要求分成4组(对照组、A、B、C组),每组设3个重复,每个重复组放30尾,分别投喂基础日粮(对照组,w(Lys)=1.25%)、添加赖氨酸盐酸盐日粮(A组,w(Lys)=1.625%)和添加不同剂量赖氨酸甲酯盐酸盐日粮(B组,w(Lys)=1.50%;C组,w(Lys)=1.625%)。结果表明:添加赖氨酸甲酯后,B、C组草鱼的增重率、特定生长率、饲料转化效率和蛋白质效率显著提高(P<0.05);鱼体的蛋白质含量和蛋白质沉积率显著提高(P<0.05),体脂含量显著降低(P<0.05);血清中总蛋白和白蛋白含量显著提高(P<0.05),而尿素氮含量显著降低(P<0.05)。添加晶体赖氨酸的A组,上述指标均未发生显著变化(P>0.05)。对照组和A组草鱼摄食后,血清中游离赖氨酸、蛋氨酸和精氨酸浓度在1 h左右达到高峰,而B、C组在3 h左右达到高峰。

A 8 - week feeding trail was undertaken to study the effects of dietary supplementation of lysine methyl ester on growth indexes in grass carp Ctenopharyngodon ideUa with initial body weight （8.34 ± 0.02） g. Three hundred and sixty healthy grass carp were randomly stocked into 12 tanks at a rate of 30 individuals per tank and fed four isocaloric and isonitrogenous diets containing various levels of lysine hydrochloride （0%, lysine accounting for 1.25 % in the diet, group D ; 0.48%, 1. 625 %, group A）, or lysine methyl ester hydrochloride （0.41%, lysine accounting for 1.50% in the diet, group B; 0.61%, 1. 625% ,group C） with triplication. The results showed that there were significantly higher weight gain rate, specific growth rate, protein efficiency ratio, protein retention efficiency, crude protein content of whole body, and serum total protein and albumin （ P 〈 0.05 ） in the fish fed the diets supplementation of lysine methyl ester hydrochloride than those in the fish fed the diets without supplementation of lysine. Meanwhile there were significantly lower feed conversion ratio, serum urea nitrogen, and crude fat content of whole body in the fish fed the diets supplementation of lysine methyl ester hydrochloride than those in the fish fed the diets without supplementation of lysine （ P 〈 0.05）. However, no significant changes in the indexes above were found in the grass carp fed the diets supplemented with lysine hydrochloride （ P 〉 0.05 ）. The fish had the maximal serum free amino acids in group D and group A 1 h after fed and in group B and group C 3 h after fed, indicating that lysine methyl ester was proved to be better dietary lysine over lysine crystalline.