Additional file 1: Supplementary Figure 1. (A) Boxplot show the relative abundance and difference of nine phyla of bacteria among four groups of laying hens. Wilcoxon rank-sum test: *, P < 0.05; **, P < 0.01, ***, P < 0.001; ****, P < 0.0001. (B) Five-fold cross-validation with five repeats were used to evaluate the importance of indicator bacterial genera, including HE versus HP, YE versus YP, HE versus YE, HP versus YP.