Effects of replacing soybean meal and rapeseed meal with faba bean meal on growth performance and muscle quality of tilapia (Oreochromis niloticus)

A 100-d feeding trial was conducted to evaluate the effects of replacing soybean meal (SBM) and rapeseed meal (RSM) with faba bean meal (FBM) on growth performance and muscle quality of tilapia. A total of 600 fish (initial body weight 500.2 ± 0.34 g) were randomly distributed into 4 groups with 3 replicates per group and 50 fish per replicate. Four diets were formulated to replace SBM and RSM with FBM at the rate of 0 % (R0), 25 % (R25), 50 % (R50) and 100 % (R100). Results showed that FBM substitute diets did not significantly alter (P > 0.05) the weight gain rate, specific growth rate, feed conversion ratio, feed intake and viscerosomatic index, but increased (P < 0.05) protein efficiency ratio in R50 and R100. The muscle crude lipid content in R100 was lower (P < 0.05) than that in R0. The muscle collagen level was increased as dietary FBM substitute increasing from 0 % to 100 % and reached significance at the rate of 50% (P < 0.05). The muscle H₂O₂ content in R50 and R100 was higher (P < 0.05) than that in R0 and R25. Dietary substitute of FBM did not significantly alter (P > 0.05) essential amino acids, but increased (P < 0.05) total non-essential amino acids and total amino acids in R100. The muscle fiber number and density were higher (P < 0.05) but the diameter was lower (P < 0.05) in FBM substitute diets than those in R0. The highest measure of textural properties was found for the R50 and R100, followed by the R25 and R0 (P < 0.05). Fish fed FBM substitute diets had higher (P < 0.05) mRNA levels of col1α1 and col1α2 in the muscle and skin than those in R0. In summary, up to 100 % of SBM and RSM can be replaced by FBM in expanded pellet diets without any adverse effects on the growth performance, but decreased muscle crude lipid content, and increased protein efficiency ratio, collagen content, H₂O₂, free amino acids, texture properties and the mRNA expressions of col1α1 and col1α2 genes in the muscle and skin of tilapia. This study will provide a practical strategy for the replacement and application of FBM in diets and improving the muscle quality of tilapia.