Herbal supplementation diet on immune response in Labeo rohita against Aphanomyces invadans

The epizootic ulcerative syndrome (EUS), caused by the fungal pathogen, Aphanomyces invadans, is one of the fish diseases of international significance in capture and culture fisheries. In this study, the effect of diet supplemented with the ethanolic leaf extract of Rauvolfia tetraphylla against A. invadans in Indian major carp, Labeo rohita was investigated to find out the innate immune response and disease resistance. In the infected fish fed with 5 g kg- 1 supplementation diet, the WBC, biochemical parameters, phagocytic, and lysozyme activity significantly increased after second week but not with other groups. However, with 5 and 10 g kg- 1 supplementation diets, the respiratory burst activity, complement activity, and myeloperoxidase activity significantly increased after third week. Interestingly, the 5 and 10 g kg- 1 supplementation diets boosted the antioxidant activity significantly after second week. This study suggests that 5 g kg- 1 enriched diet enhances innate immunity and confers disease resistance which could be applied to develop prophylactic strategies for sustainable aquaculture.