| Abstract: | To investigate the effect of dietary folic acid on fish flesh quality, muscle antioxidant status and the potential mechanism, young grass carp (Ctenopharyngodon idella) were fed diets containing 0.10–3.12 mg/kg diet of folic acid for 8 weeks. The results showed that optimum folic acid increased muscle contents of protein, lipid, pH, shear force, amino acids, unsaturated fatty acids, hydroxyproline and glutathione, whereas contents of moisture, cooking loss, lactate and saturated fatty acids and cathepsin L activity showed an opposite trend (p < .05). Moreover, optimum folic acid elevated antioxidant enzyme activities and mRNA levels, as well as NF‐E2‐related factor 2 and casein kinase 2 mRNA levels (p < .05). However, optimum folic acid decreased reactive oxygen species (ROS) content and Kelch‐like ECH‐associated protein 1a (Keap1a) and Keap1b mRNA levels (p < .05). Interestingly, excess folic acid induced negative effects on above‐mentioned parameters (p < .05). Summarily, this study indicated that optimum folic acid improved fish flesh quality and muscle antioxidant system associated with Nrf2‐Keap1 pathway. Based on muscle cathepsin L activity and ROS content, the folic acid requirements for young grass carp were 1.87 and 1.80 mg/kg diet, respectively, regarding to the flesh quality and antioxidant status. |
