The use of Zingiber officinale extract against Yersinia ruckeri and its effects on the antioxidant status and immune response in Oncorhynchus mykiss

The present work aimed to explore the effects of nutritional ginger on rainbow trout. The fish were fed various concentrations of ginger extract i.e. 1, 3, 6, and 10 g/kg; the control was fed no ginger. Having fed for 56 days, the fish were exposed to Yersinia ruckeri and any case of death was documented for two weeks. The diet with the extract of ginger could check the experimental infection in rainbow trout. The highest survival rate, i.e. 91.4%, was attained in the group nourished with ginger at 10 g/kg while the survival rate for the control was 41.6%. Ginger diet of 6 and 10 g/kg affected the biochemical parameters and the immune response. Total serum protein and total serum immunoglobulin, together with lysozyme, phagocytic, bactericidal and antioxidant enzymes activities, significantly improved in some groups, other than the control, in a dose-reliant mode (P<0.05). No variations were detected in the levels of alanine aminotransferase, lactate dehydrogenase, and aspartate aminotransferase activities in the ginger-fed groups, indicating no liver toxicity. The findings of the current research revealed that some doses of nutritional ginger (6 and 10 g/kg) could reinforce the non-specific immunity and diminish the vulnerability of rainbow trout to Y. ruckeri .