SUPPLEMENTATION OF TWO POTENTIAL PERFORMANCE INHIBITORS AND THEIR EFFECTS ON METABOLITE PROFILES IN JUVENILE RED DRUM Sciaenops ocellatus

The South Carolina DNR has utilized a natural diet of cut fish, squid, and shrimp as a positive reference diet in multiple feeding trials. Although this has mainly been incorporated as an "across-trial" reference treatment, growth performance on this treatment has always out-performed all of the >20 pelleted feeds our laboratory has evaluated. Recently, we have been able to incorporate nuclear magnetic resonance (NMR)-based metabolomics into our analyses. After profiling the metabolites found in pelleted feeds versus those observed in the natural diet feed items, we have identified multiple non-trace metabolites that are present in high soy containing feeds that are absent in the natural fish, squid, and shrimp feed items. To explore whether these metabolites may be inhibiting growth, a feeding study was carried out with a fishmeal based reference formulation and a fishmeal-free, 50% soybean meal formulation.

Two metabolites, melibiose and uridine monophosphate, that were identified as being present in the feeds and tissues of fish fed high soy containing diets, but absent from feed or tissues of fish fed natural diet items, were supplemented individually and in combination to both of the base formulations for this study. At the conclusion of the twelve week feeding trial, liver samples were taken for NMR metabolite profiling to assay differences in physiological response of juvenile red drum to the addition of these metabolites. Growth and performance metrics were also collected and analyzed. Pairwise comparisons and principle component analyses were utilized to assess the results of metabolite additions to the two base formulations.