Partial substitution of soybean meal with faba bean meal in grass carp (Ctenopharyngodon idella) diets, and the effects on muscle fatty acid composition, flesh quality, and expression of myogenic regulatory factors

Faba bean meal (FBM) was used to replace soybean meal (SBM) in different proportions, and its impacts on muscle fatty acid composition, flesh quality, and myogenic regulatory factors (MRFs) expression in grass carp (Ctenopharyngodon idella) were evaluated. Five isonitrogenous (33.7% crude protein) and isolipidic (4.1% crude lipid) diets containing different levels of FBM replacing dietary SBM (0, 9, 18, 27, and 36%) were formulated and were randomly assigned to triplicate groups of fish (mean initial weight of 3.39 +/- 0.01g) for 8weeks. No significant differences were observed between the 0% group and FBM-supplemented groups (except for 36% group). FBM instead of SBM significantly influenced the fatty acid composition and expression of MRFs, and markedly enhanced shear force and some texture parameters in muscle. Strong correlation was observed between MRFs and flesh textural properties. The maximal proportion of dietary SBM replacement with FBM was estimated to be 28.97% based on weight gain using a quadratic broken-line model. These results indicated that FBM supplementation might affect flesh quality by regulating expression of some MRFs. The substitution proportion of SBM with FBM in diets of grass carp was 28.97% based on the situation described in this study.