The immune responses of Oreochromis niloticus under different form of Bacillus supplementation

Abstract

Probiotic is considered an effective means for disease prevention in the aquaculture system. The most of probiotic species used in aquaculture were Bacillus in the form of vegetative cells. Therefore, this study evaluates the immune responses of Oreochromis niloticus under the Bacillus supplementation in the form of vegetative cells and spore. The addition of vegetative cells and spore Bacillus was given in the fish diet for 49 days. Several non-specific immune responses were evaluated afterward. Treatment without Bacillus supplementation in the diet was used as a control. The results showed that Bacillus supplementation in the form of spore and vegetative increased the non-specific immune response compared to those of control. Some parameters of the immune response, such as total leukocytes, haematocrit value, and respiratory burst, were affected by the form of Bacillus supplementation. Total haematocrit (31.67%), total leukocytes (8,2x104 cells.mm-3), Lymphocyte (81.33%) and respiratory burst (0.09 nm) of Tilapia with spore Bacillus supplementation were noted as the highest value. On the other hand, the phagocytosis activity of Tilapia was found statistically similar to vegetative or spore form of Bacillus supplementation. The factor that affected those results was the higher viability of the Bacillus spore in the fish diet. This study indicated that Bacillus supplementation in the form of spore gave the best improvement on the Tilapia non-specific immune response and could maintain the health status of the fish.