Effects of faba bean (Vicia faba) diet on amino acid and fatty acid composition, flesh quality and expression of muscle quality-related genes in muscle of "crispy" grass carp, Ctenopharyngodon idella

Faba bean meal (FBM) was used to replace protein materials in different proportions, and its impacts on amino acid and fatty acid composition, flesh quality and expression of muscle quality-related genes in muscle of grass carp (Ctenopharyngodon idella) were evaluated. In the breeding process of crispy grass carp, the addition of FB is very high, which has adverse effects on the physiological function of grass carp. In order to determine the optimum addition amount of FB in crispy grass carp culture, five isonitrogenous (approximately 33.79% crude protein, CP) and isolipidic (approximately 3.43% crude lipid) diets containing different levels of FBM replacing protein materials 0% (CON), 70% (FBM70), 80% (FBM80), 90% (FBM90) and 100% (FBM100) were formulated and were randomly assigned to triplicate groups of fish for 100 days. The results showed that FBM supplement significantly enhanced the myofiber area and radius, content of collagen and CP in muscle. Moreover, compared with the CON group, the content of inosine 5 '-monphosphate (IMP), total amino acid (TAA), total non-essential amino acid (TNAA) and the expression of collagen-related (collagen type 1 alpha 1 chain [col1a1] and collagen type 1 alpha 2 chain [col1a2]) and muscle quality-related genes (fibroblast growth factor 6a [fgf6aI] and fibroblast growth factor 6b [fgf6b]) was the highest in the FBM70 group and the lowest in the FBM100 group. In conclusion, the maximal proportion of dietary protein replacement with FBM was 70% based on the flesh quality of grass carp, which provided guidance for the cultivation of crisp grass carp.