Prebiotics (PE) and probiotics (PO) have been being studied in various fish species as natural immune enhancers in aquaculture feeds to improve immunity and intestinal microbial flora of aquatic animals. Therefore, this study was conducted to evaluate the effects of PE or PO supplementation in diet for growing red seabream on immunity and antioxidant capacity and changes in the intestinal microbial flora.
A basal diet (Con) was formulated to meet the nutrient requirement of red seabream. Dietary starch in Con were replaced with 0.6% Bio-Mos, Lactobacillus plantarum, Bacillus subtilis, Bacillus licheniformis and probiotics mixture (designed as PE-BM, PO-LP, PO-BS, PO-BL and PO-Mix, respectively). Total 450 fish were stocked into 18 polypropylene tanks (400L) in triplicated groups per dietary treatment. Fish were fed ad lubitum with one of the diets two times (08:30, 18:30 h) a day for 63 days.
Phagocytic activity was not significantly affected by the supplementation. Lysozyme activity was significantly higher in all the supplemented groups than in Con group. Immunoglobulin (Ig) of PO-Mix, antiprotease (AP) of PO-BL, glutathione peroxidase activity (GPx) and superoxide dismutase activity (SOD) of PO-BS, PO-BL and PO-Mix groups were significantly higher than that of Con group. The ratio of total Vibrio/heterotrophic bacteria counts was significantly lower in PO-LP, PO-BL and PO-Mix groups than Con group. Therefore, dietary supplementation of PE and PO is considered to improve innate immunity and antioxidant enzyme activity and inhibit Vibrio bacteria in the intestine.