|Welker, Timothy - USDA, FOREST SERVICE|
Submitted to: American Fisheries Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2009
Publication Date: August 29, 2009
Citation: Welker, T.L., Welker, T.L., Klesius, P.H. 2009. Preliminary meta-analysis on the efficacy of dietary Beta-1,3-glucan in preventing bacterial diseases in fish [abstract]. American Fisheries Society Annual Meeting. p. 662. Technical Abstract: Research on immunostimulants and their inclusion in fish feeds have increased rapidly over the past few years. Glucans, particularly ß-1,3-glucan, added to fish feeds have shown promise in not only stimulating immune function but also in increasing disease resistance. However, the results are highly variable with no clear trends discernable, even within fish species. To attempt to reach a consensus on the effect of dietary ß-1,3-glucan on bacterial diseases in fish, a meta-analysis of published research was conducted. A literature database search yielded over 100 publications examining the effects of dietary ß-glucan on immunity in fish. Of those, approximately 15 studies met our criteria for meta-analysis and had data reported in the proper format. The impact of moderator variables [fish species, warm or cold water origin, feeding duration, feeding the basal diet after experimental diet (control feeding period), Gram negative vs. Gram positive challenge bacteria, method of disease challenge (immersion vs. injection), and relative size of fish], third factors that may influence the effect of ß-1,3-glucan on susceptibility to bacterial disease, was also examined. The meta-analysis suggests that ß-1,3-glucan has a significant effect on susceptibility (mortality) of fish to bacterial disease (Hedge’s g = 0.957; P<0.0001). When moderator variables were examined, significant differences due to fish species, cold or warm water origin, control feeding period, and Gram positive vs. Gram negative challenge bacteria, but not feeding duration, immersion vs. injection disease challenge, or size of fish were observed. Due to the relatively small number of studies available for analysis, the effects of some moderator variables were heavily influenced by a few research studies (publication bias). More research is needed to provide additional data to increase the robustness of this meta-analysis. The impact of the analysis will be discussed in the context of future research.