Effects of supplementation of crystalline or coated lysine and/or methionine on growth performance and feed utilization of the Chinese sucker, Myxocyprinus asiaticus

An 8-week feeding trial was conducted using six test diets to evaluate the effects of supplementation of crystalline or coated lysine (Lys) and/or methionine (Met) on growth performance and feed utilization of the Chinese sucker, Myxocyprinus asiaticus. Test diets were fed to triplicate groups of Chinese sucker (about 3.3 g) two times a day. Five iso-nitrogenous and iso-caloric diets based on fermented soybean meal (FSBM) were prepared by either not supplementing with lysine and methionine (NLM), or supplementing with both crystalline Lys and Met (LM), with coated Lys (CL), with coated Met (CM), or with both coated Lys and Met (CLM). The control diet (FM) was formulated to contain 65% fish meal as the sole animal protein source without amino acid (AA) supplementation. The Chinese sucker juveniles fed the CL, CM and CLM diets had higher weight gain (WG) and protein efficiency ratio (PER) compared to Chinese sucker fed the NLM diet (P < 0.05). The Chinese sucker juveniles fed the CLM diet showed significantly higher growth performance than those fed the LM diet (P < 0.05). Feed intake (FI) and survival among all groups at the end of the experiment were not significantly affected by the dietary treatments. The whole body, muscle proximate, total amino acid composition showed few differences among the groups. The Chinese sucker juveniles fed the CLM diet showed significantly higher CF, HIS and VSI than those fed the NLM diet. This study indicated that the supplementation of coated lysine and methionine was effective in improving the nutritive value of FSBM-based diets deficient in methionine and lysine for juvenile Chinese sucker.