Influences of and on growth performances, immune responses, and disease resistance of Nile tilapia, .

The present study investigated the effects of and fructooligosaccharide (FOS) on growth performances, immunity improvement, and disease resistance of Nile tilapia (). The fish (24.5 ± 1.6 g) were fed a basal diet (G1), diets supplemented with 1 g/kg (G2), 3 g/kg (G3) and 5 g/kg (G4) of FOS as well as diets supplemented with 1 × 10 CFU/g (G5), 3 × 10 CFU/g (G6) and 5 × 10 CFU/g (G7) of for 56 days. After the feeding trial, the complement C3, β, α, IFN-γ, gene expression in the liver was then analyzed by a quantitative Real-time PCR. Then, fish were infected with , and the survival rate was recorded. The results showed that FOS and had no significant effect ( > 0.05) on growth performances and survival rate. Lysozyme activity was significantly greater in the G4, G5, G6, and G7 groups. Also, all fish fed FOS and showed significantly ( < 0.05) higher respiratory burst activity than other groups. The expressions of complement β, α, γ, and in the liver were significantly higher for fish fed 5 g/kg of FOS as well as for fish that received any concentration level of ( < 0.05) used in the study. After the challenge test, the survival rate of fish-fed diets supplemented with FOS and was slightly higher than for the control group. The results indicated that FOS an could stimulate immune responses and immune-related genes in tilapia. However, further investigation of other prebiotics or herbs in combination with is encouraged at molecular levels and screening for beneficial metabolites that may increasingly improve digestive enzymes, growth performances, and health benefits in tilapia. In addition, on-farm experiments are needed.