Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2005
Publication Date: 10/6/2005
Citation: Li, P., Burr, G.S., Whiteman, K.W., Davis Jr, K.B., Vega, R.R., Neil, W.H., Gatlin, D.M. 2005. A preliminary study on the effects of dietary supplemntation of brewers yeast and nucleotides, singulary or in combination, on juvenile red drum (sclaenops ocellatus). Aquaculture Nutrition. 36:1120-1127. Interpretive Summary: Juvenile red drum were raised on feed supplemented with brewers yeast or nucleotide alone or in combination for six weeks. These dietary supplements have been implicated in increasing disease resistance. There was no difference in weight gain, liver weight or intraperitoneal fat among all of the experimental diets. A 15 minute stress test did not result in a significant increase in the stress hormone cortisol. Exposure to Amyloodinium ocellatum caused 100% mortality in all groups. It appears that dietary supplementation with brewers yeast or nucleotides did not affect growth, body composition or disease resistance in red drum.
Technical Abstract: This study was designed to evaluate the effects of dietary supplementation with brewers yeast (Brewtech®) and nucleotides (Optimûn), either singularly or in combination, on red drum growth, body composition, stress responses and possible resistance to Amyloodinium ocellatum infection. Juvenile red drum (~1 g initially) fed practical fish-meal-based diets for 6 weeks had similar weight gain regardless of whether the diet was unsupplemented (basal) or supplemented with brewers yeast (2% of diet), nucleotides (Optimum at 0.2% of diet) or both brewers yeast (2% of diet) and nucleotides (Optimûn at 0.2% of diet). Dietary effects on hepatosomatic index, intraperitoneal fat ratio or whole-body composition were not significant, except that fish fed singular supplementation of nucleotide had a significantly higher whole-body lipid content compared to fish fed the basal diet. No significant dietary effects on cortisol response were observed after a 15-min confinement stress test. Subsequently, in situ challenge by co-habitation with Amyloodinium ocellatum caused 100% mortality regardless of dietary treatment within a 48-h period. It is concluded that none of these dietary supplementation strategies promoted enhanced growth nor improved stress responses and resistance to uncontrolled amyloodiniosis in juvenile red drum.