Effects of alpha-tocopheryl acetate supplementation in preslaughter diet on antioxidant enzyme activities and fillet quality of commercial-size Sparus macrocephalus.

This study examined the effects of dietary alpha-tocopheryl acetate supplementation on antioxidant enzyme activities and fillet quality in commercial-size Sparus macrocephalus. Three hundred fish [main initial weight (350+/-12) g] were divided into three groups (E250, E500 and E1000) and reared in 9 cages. The fish were fed for 8 weeks with three diets containing different levels of dietary alpha-tocopheryl acetate (289, 553, 1 069 mg/kg). Over the experimental period, fish were fed to satiation and reached a final mean weight of (465+/-28) g without significant body weight difference and proximate composition difference. Fillet alpha-tocopherol was significantly (P<0.05) different between groups, reaching levels of 14.2, 22.1, 30.9 microg/mg fillet for groups E250, E500 and E1000, respectively. Total serum superoxide dismutase (SOD) activity increased significantly (P<0.05) in fish fed the diets high in alpha-tocopheryl acetate, but serum glutathione peroxidase (GPX) activity was unaffected. In storage on ice, fillets of fish fed the diets high in alpha-tocopheryl acetate exhibited significantly lower (P<0.05) levels of oxidation. These results suggested that increased dietary alpha-tocopheryl acetate could increase its flesh deposition, increase the activity of SOD and prevent lipid peroxidation of Sparus macrocephalus fillets in retail storage on ice.