Effect of Feed and Water Additives on Bacterial Composition in a Shallow-Water Shrimp (Litopenaeus vannamei) Research System Using Biofloc Technology

The effects different prebiotics, organic acid salts and an essential oil blend have on the bacterial community of biofloc particles (formed of bacteria, leftover feed, and feces) and shrimp gills tissue, hepatopancreas and intestinal contents, as well as on total hemocyte count (THC), were determined for the Pacific white shrimp, Litopenaeus vannamei. Shrimp were stocked in research tanks with a capacity to hold 41-L of artificial 28 g/L salinity. Final weight, weight gain and survival were determined based on termination data. Also, biofloc and shrimp muscle samples were collected to determine ash, protein and lipid composition. In addition, denaturing gradient gel electrophoresis of biofloc and shrimp hepatopancreas, gills and intestine was conducted. For Trial I, prebiotics, fructooligosaccharide, galactooligosaccharide, mannan-oligosaccharide and inulin, as well as non-prebiotic carbohydrates, wheat starch and sucrose, were added directly to the water. For Trial II, the same additives of Trial I and an essential oil blend were included in the feed with a 3% dietary inclusion level. For Trial III, four diets were prepared with fructooligosaccharide and galactooligosaccharide at 1.5 and 3.0% dietary inclusion level each. Also, 6 diets were prepared with sodium acetate, sodium lactate and sodium propionate each at 0.75 and 1.5% dietary inclusion levels and a control diet with no additive inclusion. For the present experimental conditions, it can be concluded that the evaluated additives have a significant effect on the bacterial communities of the biofloc and those present in shrimp gills, hepatopancreas and intestinal contents when added to the water or feed. Significant increase in the THC was observed when the essential oil blend and the organic acid salts were included in feed of Trials II and III. Also, significant effects on water quality and biofloc levels were observed only when wheat starch was added to the culture water. The effects of feed and water additives on the bacterial populations of biofloc and shrimp gills, hepatopancreas and intestinal contents as well as on THC of shrimp when cultured in a biofloc technology system is a significant contribution to knowledge and to the shrimp aquaculture industry