Ileal mucosa-associated bacteria during the postweaning period at day 51 of age in male piglets fed human milk (HM, n = 14) or milk formula (MF, n = 14) from day 2 until day 21 of age followed by solid diet until day 51. (A) The taxonomic composition of bacterial phyla detected in HM and MF groups. (B) The beta diversity at the bacterial species level analyzed by principal-coordinate analysis (PCoA). (C) The alpha diversity at the bacterial species level analyzed by observed species, Chao1, Shannon, and Simpson indices. (D) Significant differences in bacterial species (P < 0.05) detected between HM and MF groups. (E) Significant differences in predicted metabolic functions (P < 0.05) for the metagenome gene profile detected between HM and MF groups.