Effect of Grapefruit (Citrus paradisi) peel extract on growth performance and antioxidant activities of kutum (Rutilus kutum) fry

In this study, the effects of the hydro-alcoholic extract of grapefruit peel (Citrus paradisi) on growth performance and some antioxidant parameters of Caspian white fish (Rutilus kutum) blood plasma were investigated. Accordingly, 180 fry fish with an initial mean weight of 4.0 ± 0.3 g were fed with diets containing 0, 6.25, 12.5 and 25 mg hydro-alcoholic extract of grapefruit peel per kg feed. The fry fish were cultured for 56 days. The highest amounts of body weight gain (50.10±6.18 %), specific growth rate (3.05±0.79 % per day) as well as the lowest feed conversion ratio (1.32±0.11) were observed in the fish fed with Grapefruit juice extract 25 mg/kg hydro-alcoholic extract of grapefruit peel (p < 0.05). There were no significant differences between treatments in condition factor and survival percentage (P>0.05). In addition, the highest activities of antioxidant enzymes including glutathione peroxidase enzyme and catalase enzyme were observed in 25 mg/kg hydro-alcoholic extract of grapefruit peel. Also, superoxide dismutase enzyme was significantly increased in fish fed with hydro-alcoholic extract of grapefruit peel compared to the control group. In general, supplementation of the Caspian white fish feed with hydro alcoholic extract of grapefruit peel at 25 mg/kg of feed can improve growth performance and antioxidant responses.