Submitted to: Journal of Applied Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2005
Publication Date: 3/1/2006
Citation: Shelby, R.A., Lim, C.E., Aksoy, M., Delaney, M.A. 2006. Effects of probiotic feed supplements on disease resistance and immune response of young Nile tilapia (Oreochromis niloticus). Journal of Applied Aquaculture 2006, 18(2) 22-34. Interpretive Summary: We conducted two separate experiments to determine the effects of commercially available probiotic feed additive on young Nile tilapia. The probiotics were in the form of formulated powders containing combinations of live bacteria or yeasts, which we added to commercial diets. The genera Bacillus, Pediococcus, Enterococcus and Saccharomyces were represented in the two tests. We recovered live bacteria or yeast from the formulated product in the quantities and of the species stated on the label. We also recovered live bacteria in higher numbers from the intestine of tilapia fed the probiotic. There was a measurably higher survival in tilapia receiving a Bacillus probiotic. We were unable, however, to show a significant increase in immune response measured by lysozyme, immunoglobulin, complement, or disease resistance when challenged by Streptococcus iniae. The results suggest that these probiotics formulations are more suitable for terrestrial livestock, but further testing of these and other probiotic feed additives is warranted.
Technical Abstract: Probiotic microbial feed supplements are gaining wide acceptance in livestock production, and may be applicable to aquaculture production systems. In two experiments, we fed fry of Nile tilapia (Oreochromis niloticus) 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 Streptoccus 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 tialpia.