The Biochemical, Pathological and Immunological Effectiveness of Commercial Probiotics in Nile Tilapia, Oreochromis niloticus

Improved resistance against diseases in Nile tilapia, Oreochromis niloticus can be achieved by probiotics. A total of 450 fish (50+/-5 g) were divided into 5 groups: 1st group received diet with 0.1 ml/kg C.A growth (R) probiotic, 2nd group received diet with 0.2 ml/kg feed C.A growth (R) probiotic, 3rd group received diet with 0.15 g/kg feed Tonolest (R) probiotic, 4th group received diet with 0.3 g/kg feed Tonolest (R) probiotic, 5th group was fed on probiotic-free diet. Eight weeks later, fish fed C.A growth (R) probiotic revealed significant increase in phagocytic activity, differential leucocytic count, serum lysozyme and bactericidal activity, total protein and globulin levels than fish fed on Tonolest (R) probiotic. Moreover, groups receiving C.A growth (R) probiotic showed significant increase in antibody titre against Aeromonas hydrophila than other groups. In addition, Nile tilapia receiving C.A growth (R) probiotic showed significant decrease in cortisol hormone and bacterial counts in gastrointestinal tract than fish receiving Tonolest (R) probiotic in all weeks. C.A growth (R) probiotic evoked no/limited cellular damage and decreased pathological lesions in groups challenged with A. hydrophila. On the other hand, Tonolest (R) probiotic evoked more pathological damage in organs especially with high dose and less effective in decreasing pathological changes in groups challenged with A. hydrophila.