Figure 2

Treatment effects on diversity and composition of cecal microbiota. Alpha diversity indices were calculated on rarefied samples at the lowest subsample size of 9,000 sequences per sample. There was no significant (nonparametric t-test, P > 0.05) effects of prebiotic or antibiotic on the observed number of OTUs (A) and phylogenetic diversity (whole tree) (B). Error bars show standard deviation for each category. Unweighted UniFrac PCoA plot shows no separation of bacterial communities between dietary groups (C). Key phylotypes of cecal microbiota responding to dietary treatments were identified using LEfSe algorithm (D). The histogram shows the increased abundance of the genus Lactobacillus in the cecal microbiota of chickens fed HXOS diet compared with other treatments (E). Each bar represents the relative abundance of the taxa in a sample at the age of 15 (red line), 25 (green line), and 35 days (blue line). The mean and median relative abundance are indicated with solid and dashed lines, respectively. CTL: control diet without any antibiotic or prebiotic; VIRG: control diet supplemented with 16.5 g/ton virginiamycin; LXOS: control diet supplemented with 1 g/kg xylo-oligosaccharides; HXOS: control diet supplemented with 2 g/kg xylo-oligosaccharides.