Role of probiotics in improving growth performance, immunity and controlling Aeromonas hydrophila in the Nile tilapia Oreochromis niloticus

The tilapias were treated with of Enterococcus faecium and Bacillus coagulans at a final concentration of (10^7cfu/g) (10^7cfu/g). 18 aquaria with 6 replicates for treated and controls were used. After 75 days, the tilapias supplemented with the probiotic showed significantly better final weight, body length, specific growth rate, weight gain, feed intake, feed conversion ratio and protein efficiency ratio than those fed on the basal diet (Control). After 75 days from experiment start, each experimental fish group was divided into two groups; the first group was infected with Aeromonas hydrophila while the second group without infection. The best Hb, Htc, MCV and RBCs content was recorded by fish group fed on the E. faecium supplemented diet comparing to fish group fed on the basil diet and infected with A. hydrophila and the same trend was observed for mortality rate. The highest WBCs value and differential count were recorded fish groups infected with A. hydrophila. Results also showed that, fish fed on the diet supplemented with E. faecium followed by Bacillus coagulans recorded the lowest (P 0.001) AST value (16.3 u/L) and (17.23 u/L), while control positive Aeromonas hydrophila group showed the highest (P 0.001) values being 29.6 u/L.