Effect of dietary prebiotic supplementation on the performance, intestinal microflora, and immune response of broilers.

This study investigated the effects of dietary supplementation with the prebiotics fructo-oligosaccharide (FOS) and mannan-oligosaccharide (MOS) on the performance, small intestinal microflora, and immune response of broilers. Two hundred forty 1-d-old Ross broiler chickens were randomly assigned to 6 dietary treatment groups: control, avilamycin (6 mg/kg), 0.25% FOS, 0.5% FOS, 0.025% MOS, and 0.05% MOS. Each treatment was fed to 4 replicates of 10 birds per diet for 4 wk. Except for the 0.5% FOS group, the overall BW gains of birds treated with avilamycin and prebiotics were significantly(P < 0.05) higher than those of the control group. No significant differences were found between the control and supplemented groups in overall feed intake, feed conversion, and mortality. The 0.05% MOS group was significantly (P < 0.05) lower than the control and 0.5% FOS groups in heterophil:lymphocyte ratio and basophil level. Concentrations of plasma IgA and IgG were not significantly different among the treatment groups. Quantitative real-time PCR indicated that supplementation of the diet with avilamycin or prebiotics caused significant (P < 0.05) changes in the small intestinal microbial community, as determined in samples obtained at the ileocecal junction. The populations of Clostridium perfringens and Escherichia coli decreased with 0.25% FOS, 0.05% MOS, or avilamycin, and lactobacilli increased in the 0.25% FOS and 0.25% MOS treatment groups. Total bacteria increased in the 0.25% FOS and 0.05% MOS treatments and decreased in the avilamycin treatment. Feeding 0.25% FOS and 0.05% MOS resulted in an increase in lactobacillus community diversity in the ileum. Our results showed that 0.25% FOS and 0.05% MOS were comparable with avilamycin in improving productivity in broilers raised in wire floor cages up to 28 d of age. Plasma immunoglobulins were not affected by prebiotics, but the heterophil:lymphocyte ratio, basophil level, and microbial population in the ileum were significantly affected.