|Gatlin, Iii, Delbert - Texas A&M University|
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2009
Publication Date: 7/31/2009
Citation: Burr, G., Gatlin III, D.M., Hume, M.E. 2009. Effects of the prebiotics GroBiotic-A and inulin on the intestinal microbiota of red drum, Sciaenops ocellatus. Journal of the World Aquaculture Society. 40:440-449.
Interpretive Summary: Two separate experiments examined the effects of two dietary supplements, GroBiotic®-A and inulin, on fish growth and bacteria in the digestive tracts of the red drum, a popular aquaculture-grown food fish. In the first experiment, fish were fed fishmeal-based diets without or with either GroBiotic®-A or inulin. In the second experiment, fish were fed soybean meal/fish meal-based diets without or with either GroBiotic®-A or inulin. Feeding the fish GroBiotic®-A or inulin in either experiment did not alter weight gain. The types of bacteria in the digestive tracts were not affected by the diets. Each community of bacteria had very low numbers of different types of bacteria present. Additionally, fish in these experiments contained very low numbers of different types of bacteria in the digestive tract when compared to livestock and other fish species. An examination of the water filters in each independent tank revealed many different types of bacteria were present. More different types of bacteria were seen in the filters than in the fish digestive tract. The different types of bacteria present on the filters were not affected by the dietary supplements. The results illustrate the ineffectiveness of these supplements to increase growth and to change the types of bacteria found in the digestive tract. These results are of interest to producers of researchers investigating the effects of feed supplements on digestive bacteria, fish researchers, fish feed supplements, and aquaculture producers of fish as food animals.
Technical Abstract: Two separate feeding trials examined the effects of dietary supplementation of the prebiotics GroBiotic®-A and inulin on growth performance and gastrointestinal tract microbiota of the red drum Sciaenops ocellatus. In the first feeding trial, fishmeal-based diets without prebiotics or supplemented with either GroBiotic®-A or inulin at 1% of dry weight were fed to triplicate groups of juvenile red drum (initial weight of 2.6 g) in 110-L aquaria operated as a brackish water (7 ppt) recirculating system for 8 weeks. In the second feeding trial, soybean meal/fish meal based diets supplemented with either GroBiotic®-A or inulin at 1% of dry weight were fed to triplicate groups of red drum (initial weight of 15.8 g) in 110-L aquaria operated as either a common recirculating water system or closed system with individual biofilters (independent aquaria) for 6 weeks. Supplementation of the prebiotics in either feeding trial did not alter weight gain, feed efficiency ratio or protein efficiency ratio of red drum fed the various diets. In the second feeding trial, the culture system significantly affected weight gain, feed efficiency ratio and protein efficiency ratio although there were no effects of dietary treatments on fish performance or whole-body protein, lipid, moisture or ash. Denaturing gradient gel electrophoresis (DGGE) analysis of the gastrointestinal tract microbial community revealed no effect of the dietary prebiotics as the microbial community appeared to be dominated by a single organism with very low diversity when compared to other livestock and fish species. Denaturing gradient gel electrophoresis of the microbial community in the biofilters of the independent aquariums revealed a diverse microbial community that was not affected by the dietary prebiotics.