Submitted to: American Fisheries Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 2008
Publication Date: August 17, 2008
Citation: Welker, T.L., Lim, C.E., Shelby, R.A., Aksoy, M., Klesius, P.H. 2008. Effect of Dietary Immunostimulants on Immunity and Disease Resistance of Channel Catfish and Nile Tilapia. American Fisheries Society Annual Meeting. Available: http://www.fisheries.org/AFS08/docs/prog.pdf Technical Abstract: Research suggests that immunostimulants added to diets can improve the ability of fish to respond to disease challenge. However, the effectiveness of most immunostimulants, even within a species, can vary considerably. We have conducted several studies examining the effects of whole-cell yeast (Saccharomyces cerevisiae) and yeast-subcomponents (ß-glucans and mannan oligosaccharides) (YYS), bovine lactoferrin, and probiotics (various bacterial species) added to diets on immune function and disease resistance in channel catfish and Nile tilapia. Results have been inconsistent. Feeding diets containing commercially available, live probiotic bacteria (Saccharomyces, Bacillus, Pediococcus, and Enterococcus sp.) did not affect immune function or improve resistance of catfish or tilapia to bacterial challenge. When fed YYS-supplemented diets, fish also did not show improvement in immune function or disease resistance after 4 or 6 weeks of feeding, but shorter feeding durations of 1 or 2 weeks appears promising in channel catfish. However, dietary supplementation of bovine lactoferrin increased survival of both channel catfish and Nile tilapia to disease challenge, possibly by limiting iron availability to the challenge bacterium. Results from these studies will be summarized and discussed. Further research is needed and continues on the effects of immunostimulants on immunity and disease resistance in channel catfish and tilapia.