Influence of dietary zinc on muscle composition, flesh quality and muscle antioxidant status of young grass carp (Ctenopharyngodon idellaVal.)

This study was conducted to investigate graded levels of dietary zinc on the growth, flesh quality, and the relationship between flesh quality and muscle antioxidant status in young grass carp (Ctenopharyngodon idella Val.). Per cent weight gain (PWG), special growth rate (SGR), feed intake (FI), feed conversion ratio (FCR), anti-hydroxy radical (AHR), superoxide dismutase (SOD), catalase (CAT), glutathione reducase (GR) activities and glutathione (GSH) content were significantly increased with increasing levels of Zn up to a point, and thereafter declined (P < 0.05). Serum zinc, alkaline phosphatase (AKP), muscle anti-superoxide anion (ASA), glutathione peroxidase (GPx), glutathione-S-transferase (GST) activities and collagen content were significantly enhanced with dietary zinc levels up to a point (P < 0.05), beyond which it plateaued. Cooking loss, shear force and malondialdehyde (MDA) were significantly reduced with increasing level of zinc up to a point, and thereafter increased (P < 0.05). The pH value significantly increased with the increasing zinc levels, whereas the trend of protein carbonyl content was opposite. Flesh quality was positively related to the antioxidant enzymes activities in muscle of young grass carp. These results indicated that optimum zinc could improve growth, and improve flesh quality partly through improving muscle antioxidant status of young grass carp.