Phagocytes response to dietary probiotics SEAL and Aeromonas hydrophila infection in red tilapia (Oreochromis sp.)

Abstract

Abstract This study focusses on the effect of the probiotic application on the phagocytosis activity, phagocytic index, and respiratory burst in red tilapia nilasa strain infected with Aeromonas hydrophila. Yeast and bacterial strains of different origins (Sacharomyces sp. FNCC3015, Enterobacter sp. JC10, Aeromonas sp. JC33, and Lactococcus sp. JAL12) were administered to fish in daily, and three-day intervals at a dose of 5x104 CFU/gram feed. The control groups were only administered with fish pellets with saline buffer. Fish were infected with A. hydrophila in the LD70 dose on 23rd day of treatment. Phagocytic activity of blood leukocytes and blood respiratory burst were examined at one and two months of probiotic application, and 7 days after pathogenic bacteria infection. Administration of yeast and bacterial strains to fish before A. hydrophila infection elevated and prolonged phagocytic activity of blood leukocytes at the first and second months of application. No significant improvement of the phagocytic index and blood respiratory burst was found in the present study. It is therefore concluded that probiotics application at three-day interval is sufficient to stimulate and enhance the phagocytes performance of red tilapia nilasa strain before and after A. hydrophila infection.