Lactobacillus plantarum Caused Improved Growth and Immunocompetence and Reduced Pathogenic Microbes in Monosex Oreochromis niloticus

Background and Objective: The sustainable production of sex-reversed Oreochromis niloticus is challenged by disease outbreaks resulting from high stocking densities and indiscriminate use of synthetic drugs in its production. Thus, the probiotic effects of Lactobacillus plantarum in sexually reversed male tilapia using growth, serum biochemical and gut microflora indices were evaluated in this study. Materials and Methods: Basal diet was supplemented with 0 (Lp0), 1.5×108 (Lp1), 3.0×108 (Lp2), or 4.5×108 CFU mL‾1 (Lp3) Lactobacillus plantarum and fed to triplicate sets of all male O. niloticus (2.23±0.04 g) to apparent satiation twice daily for 84 days. Results: The higher weight gain (9.56±0.63 g), specific growth rate (1.98±0.05%), protein efficiency ratio (1.61±0.05 g) and superior feed conversion ratio (1.61±0.05 g) in fish fed Lp1 (p<0.05) while corresponding least values were observed in Lp0. Histology revealed disseminated steatosis in the liver of all samples including the control. Lactobacillus plantarum increased significantly (p<0.05) hemoglobin, packed cell volume, white and red cell counts, serum protein, alkaline phosphatase and the levels of alanine aminotransferase (ALT) and aspartate transaminase (AST) were reduced significantly (p<0.05) in fish blood. Liver function was improved as shown in the decrease recorded in the measured liver enzyme (AST and ALT) activities. Conclusion: The Lactobacillus plantarum causes an improvement in the health status and growth of Oreochromis niloticus.