Combination of lysine and histidine improves growth performance, expression of muscle growth‐related genes and fillet quality of grow‐out Nile tilapia

This study aimed to evaluate the effects of lysine and histidine supplementation on growth performance, gene expression, blood parameters and quality of the fillet in Nile tilapia, Oreochromis niloticus (n = 192; 136.14 ± 2.32 g). Fish were distributed into four groups and fed a control diet without lysine and histidine supplementation (CON), supplemented with lysine (LYS), histidine (HIS) or lysine and histidine (LYS + HIS) and fed until apparent satiety for 90 days. Growth performance increased significantly in fish fed diet LYS + HIS (p < .05). The fillet body weight gain and fillet yield increased by 26.61% and 2.74% unit, respectively, compared to fish fed CON diet (p < .001). Compared to the control group, fish fed diets showed decreased whole-body lipid and plasmatic triglycerides coupled to increased mRNA levels of MyoD and myogenin in the skeletal muscle and higher texture attributes of fillets (p < .05). There was a substantial negative correlation between body lipids and hardness of fillets. Overall, the combined supplementation of lysine and histidine optimizes growth performance, expression of muscle growth-related genes and flesh quality attributes in grow-out Nile tilapia.