Antioxidant role and immunological function of Excoecaria agallocha in Amphiprion sebae against Vibrio alginolyticus

Abstract

The efficacy of supplementation diet with 0, 2.5, 5, and 10 g kg-1 of Excoecaria agallocha aqueous leaf extract on innate immune response, survival, and disease resistance was reported in clownfish, Amphiprion sebae against Vibrio alginolyticus. The mean weight gain (MWG), specific growth rate (SGR), and protein efficiency ratio (PER) did not significantly vary with any supplementation diet except with 5 g kg-1 diet on weeks 6 and 8. The white blood cell (WBC) level significantly increased with any supplementation diets on weeks 6 and 8. The phagocytic activity, alternate complement activity, and lysozyme activity increased significantly with 5 and 10 g kg-1 diet on weeks 6 and 8 whereas the respiratory burst activity significantly increased with any supplementation diets on weeks 6 and 8. The cumulative mortality with the 2.5 and 10 g kg-1 supplementation diets were 10% against V. alginolyticus whereas with 5 g kg-1 supplementation diet only 5%. V. alginolyticus count was high in infected fish fed with control diet as well as the infected fish fed with 2.5 g kg-1 diet had high bacterial count (cfu/g) in kidney, blood, and spleen (1.4 x 102, 1.1 x 103, and 1.2 x 103) whereas it was low with 10 g kg-1 diet in blood, spleen, and kidney (0.6 x 101, 0.2 x 101, and 0.2 x 101). The present results indicate that infected fish fed diet containing 5 and 10 g kg-1 of E. agallocha positively enhance the innate immune response and reduce the mortality in A. sebae against V. alginolyticus infection. Keywords: Disease resistance; Excoecaria agallocha; Innate immune parameter; Mortality; Vibrio alginolyticus