Abstract: 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.
2009, Vol. 24 
