Improvement growth and immune status using a potential probiotic bacteria Micrococcus species among Culured Oreochromis niloticus

ABSTRACT Probiotic bacteria Micrococcus species isolated from the gonads of apparently healthy Oreochromis niloticus was harmless to O. niloticus and had antagonistic effect against the pathogenic Aeromonas hydrophila invitro. The inhibition zone to A. hydrohpila was 47 mm in diameter due to M. species. The effect of supplemental dietary probiotic bacteria (pseudomonas sp.10 7 cells/g food) on some heamatological parameter, growth performance and survival rate of O. niloticus. were divided to two groups, with three replicates each. Fish were fed frequently on a diet (5% of body weight) three times daily for 60 days. The obtained results showed that the final weight, weight gain, specific growth rate and protein efficiency ratio of O. niloticus increased significantly in the treated fish, when compared to the untreated group. Also, feed conversion ratio was lower in the treated group than the control one. Erythrocytic counts and hemoglobin content total serum protein, A/G ratio and phagocytic activity in fish fed on diets containing M. species were higher than that of the control group. After feeding sixty days O. niloticus was challenged I/P by A. hydrophila 0.3×10 7 cells/ml. The survival rate was 75% with M. species while, it was 20% in the control group. Thus, the isolated M. sp. was harmless to O. niloticus and had probiotic effect in vitro and in vivo