Dietary Supplementation Impacts of Potential Non-Pathogenic Isolates on Growth Performance, Hematological Parameters and Disease Resistance in Nile Tilapia (Oreochromis Niloticus)

Pseudomonas fluorescens biovars were isolated from Oreochromis niloticus collected from Qaroun Lake fish farms, Egypt. Microorganisms were added to basal diet with 30 % protein to assess their probiotic properties on growth-performance, hematological parameters, enzymatic activities and survival rate. Tilapia (2.93 ± 0.22 g) were distributed into four equal groups, three replicates each. First group were fed on basal diet as control group, 2nd, 3rd and 4th groups were fed on diet supplemented with Pseudomonas fluorescens biovar I, II & III respectively; fish were fed twice daily at the rate of 5-7 % of their body weight for 45 days. The groups were challenged intra-peritoneal with Aeromonas hydrophila (1.8 x 108 CFU ml?1) and observed for 7 days. The growth rate was significantly higher in groups fed on Pseudomonas fluorescens in the diet than control group. Hematological and non-specific immune parameters were significantly higher than control group. The highest protein, globulin, glucose, Plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenases activity were observed at 3rd group which fed on Pseudomonas fluorescens biovar II. The challenged fish exhibited lowest cumulative mortality rate in 3rd group (10%) compared to control group (90%). So, it could be concluded that non-pathogenic pseudomonas isolates from marine or brackish water could confer beneficiary effects for Nile tilapia through improving growth performance, immunity enhancement and resistance against diseases.