The study was conducted to investigate the effect of diets containing 0, 2.5, 5, 7.5, and 10% S. platensis meal on total antioxidant capacity (TAC) and lipid peroxidation, as well as the expression of two antioxidant enzyme genes (SOD and CAT) in rainbow trout (Oncorhynchus mykiss). One hundred and eighty fish, with an average initial weight of 101 ± 8 g, were cultured for 10 weeks. At the end of experiment, lipid peroxidation significantly decreased in serum of fish fed with S. platensis and fish fed with 5, 7.5, and 10% microalgae showed a significantly lower value compared to control and 2.5%. Inclusion of 7.5 and 10% S. platensis in diet also decreased lipid peroxidation in liver. TAC significantly increased with increasing level of S. platensis. Expression level of superoxide dismutase (SOD) and catalase (CAT) genes significantly increased in the fish liver after administration of microalgae and fish fed with 10% S. platensis in diet showed the highest level compared to the other treatments. The present study reveals that inclusion of 10% S. platensis in diet can decrease oxidative stress in rainbow trout. Therefore, S. platensis can be used as potential antioxidant for fish farming.
Keywords: Antioxidant gene expression; Lipid peroxidation; Rainbow trout (Oncorhynchus mykiss); Spirulina platensis; Total antioxidant capacity (TAC).