LAUSR

Abstract Fermented soybean meal (FSM) is used as a potential substitute for fishmeal in various aquatic species due to its enriched nutrient profile. This study is aimed to investigate the effect of two different kinds of FSM on growth and protein metabolism in the Chinese mitten crabs (Eriocheir sinensis). One hundred and sixty-eight crabs were randomly assigned to 21 cement pools, each with eight crabs. The crabs in the control group were fed a basic diet, without FSM. Six isonitrogenous and isolipidic diets were prepared by replacing fish meal with two kinds (A and B) of FSM at concentrations of 5 %, 10 %, and 15 %, respectively. The results showed that partial replacement of fish meal with FSM could improve the growth performance of and crude protein content in the Chinese mitten crabs. In addition, increased activities of trypsin, pepsin, Na+/K+-ATPase, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase in the Chinese mitten crabs were observed. Furthermore, the hepatopancreas mRNA levels of protein metabolism-related genes, including protein kinase B (Akt), protein S6 kinase 1 (S6k1), 4E-binding protein 1 (4E-BP1), and oligopeptide transporter 1 (Pept1), were higher in the crabs fed FSM-supplemented diets than in the control crabs. The present study concludes that about 10 and 15 % of fish meal could be substituted by FSM A and B, respectively, without having any deleterious effects on growth performance, protein metabolism-related enzyme activities, and the expression ofand protein synthesis- and metabolism-related genes expressions.