Effects of Probiotic Diet Supplements on Disease Resistance and Immune Response of Young Nile Tilapia,<i>Oreochromis niloticus</i>

Abstract

Abstract Probiotic microbial feed supplements are gaining wide acceptance in livestock production, and may be applicable to aquaculture production systems. In two experiments, fry of Nile tilapia, Oreochromis niloticuswere fed a basal diet supplemented with commercially-available probiotic microorganisms. Survival, growth, disease resistance, and immunological parameters were monitored for a maximum of 94 days. Bacterial populations were higher in the digestive tracts of tilapia receiving probiotic diets, and colony morphology suggested that viable probiotic bacteria persisted up to 48 hours after feeding. Survival was higher after 39–63 days in fish receiving the Bioplus probiotic, Bacillus spp. There was no difference in growth, lysozyme, total serum immunoglobulin, complement, specific anti-streptococcal antibody levels, or mortality due to Streptococcus iniae infection either before or after disease challenge. The results suggest that these commercially-available probiotic microorganisms do not provide beneficial effects in young Nile tilapia. Key Words: Probioticstilapia Oreochromis niloticus Streptococcus iniae Bacillus Pediococcus Enterococcus Saccharomyces