Effects Of Clostridium Butyricum On Growth, Digestive Enzyme Activity, Antioxidant Capacity And Gut Microbiota In Farmed Tilapia (Oreochromis Niloticus)

The effects of a commercial probiotic (Clostridium butyricum) on growth, gut microbiota, digestion-related enzyme activity, antioxidant capacity and water quality in genetically improved, farmed tilapia (GIFT; Oreochromis niloticus) were assessed in a closed-circuit, container culture system. A basal diet containing commercially available C. butyricum at 3.0 x 10(10), 1.5 x 10(11) and 3.0 x 10(11) CFU/kg, and a control diet were fed to tilapia fries for 90 days. Growth performances and water quality were improved by probiotic treatment. Activities of digestive enzymes (amylase, lipase and trypsin) were improved, especially with 1.5 x 10(11) CFU/kg (p < 0.05). After feeding for 45 days and 90 days, antioxidant capacity in the liver, spleen and head kidney, and the plasma immunity in the treatment groups improved. The analysis of 16S rRNA indicated that C. butyricum did not significantly increase its abundance in the hindgut, but could modulate gut microbial communities and significantly increase functions relating to nitrogen metabolism, phosphorylation and proteinases. These results support the administration of C. butyricum, especially at 1.5 x 10(11) CFU/kg. As a probiotic for high-density tilapia, C. butyricum improves water quality, growth performance, antioxidant capacity and the immune response of GIFT under crowding stress.