Cytokine gene expression, immune responses and disease resistance of oncorhynchus mykiss after raphanus sativus by-products supplementation

Abstract

In the present study, we examined the effects of aqueous methanolic extract of radish seed (Raphanus sativus) by-products (RS) on innate immune responses and growth performance of rainbow trout (Oncorhynchus mykiss). The fish was fed diets containing 4 different doses of RS (0 % (Control), 0.1% (RS0.1), 0.5% (RS0.5) and 1% (RS1)) for 14 days. The results showed an increased activity of respiratory burst in fish of treatment groups compared to that of control on 14th day (P<0.05). An enhanced bacterial killing activity was observed in R.05 and RS1 treatment groups compared to control (P<0.05) on 7th day of the study. Lysozyme activity was elevated in fish of RS1 group on 7th day, and in all treatment groups on 14th day compared to that of the control. Myeloperoxidase activity increased significantly in RS1 and RS0.1 groups compared to the control on 7th day. IL-1b was up-regulated in head kidney of fish in RS0.1 group on 7th day and in RS0.5 group on 14th day of the study. In intestine of fish of experimental groups, IL-1b expression was significantly elevated on 7th day compared to the control. IL-12 was also up-regulated both in kidney and intestine of treatment group fish on 7th day. Similar results were observed on IL-10 expression. IL-8 was up-regulated both in kidney and intestine of treated fish groups. Growth performance was affected positively in the RS1 group compared to the control. However, FCR value did not vary among different groups. Survival also improved against Aeromonas hydrophila infection in RS administered fish. All these results suggest that supplementation of RS through diets for 7 days could improve immune responses and growth in rainbow trout.