Nutritional effects of ginger (Zingiber officinale Roscoe) on immune response of Asian sea bass, Lates calcarifer (Bloch) and disease resistance against Vibrio harveyi

The present study was aimed at determining the effects of ginger (Zingiber officinale Roscoe) as feed additive on Asian sea bass, Lates calcarifer culture. Experimental diets containing ginger 1, 2, 3, 5 and 10 g/kg of feed were fed to L. calcarifer and control was fed with no ginger. After the feeding trial for 15 days, fish were challenged with Vibrio harveyi and mortality was recorded for two weeks. Ginger diet led to control of experimental infection in L. calcarifer. Highest survival (86.6%) was achieved in groups fed with ginger at 5 and 10 g/kg feed respectively, compared to the control (26.7%). In addition, there was a significant increase in weight gain, growth and feed conversion in those fish fed ginger diet. Ginger diet influenced the haematological parameters, biochemical indices and immunological activities. The number of erythrocytes (RBC) and leucocytes (WBC) was significantly (p < 0.05) higher in the groups fed ginger diet compared to the control. The blood glucose level, lipid, triglyceride and cholesterol levels were relatively lower in treated groups compared with the control. Phagocytic, respiratory burst, lysozyme, bactericidal and antiprotease activities were significantly increased in ginger fed groups compared with the control. The results of this study demonstrated that dietary ginger doses might strengthen the non-specific immunity and reduce susceptibility to V. harveyi.