Functional maturation of the gut microbiota at weaning is influenced by maternal environment in piglets

The objective of this study was to analyze in piglets the impact of weaning on the production of metabolites by gut bacteria and to determine whether early life environment influences the functional maturation of the gut microbiota. Fecal metabolome and microbiome were analyzed in piglets raised in two separate maternity farms and mixed at weaning. In piglets from both maternity farms, the relative abundance of Lactobacillus and of the predicted function "Fucose degradation" decreased after weaning while the relative abundance of Ruminococcus 2 and of the predicted function "Starch degradation" increased. In piglets from the first maternity farm, the relative concentration of biogenic amines and the relative abundance of Escherichi-Shigella decreased after weaning while the relative concentration of short chain fatty acids and the relative abundance of Christensenellaceae R-7 group and Ruminococcaceae UCG-002 increased. These changes were not observed at weaning in piglets from the second maternity farm probably because they already had high relative concentration of short chain fatty acids and higher relative abundance of Christensenellaceae R-7 group and Ruminococcaceae UCG-002 during the suckling period. In conclusion, the functional maturation of the microbiota at weaning is highly dependent on the maternal environment in piglets. ORIGINALITY - SIGNIFICANCE STATEMENTBacterial metabolites are key molecular intermediates between the gut microbiota and host cells. Our study in piglets reveals that the metabolic activity of the gut microbiota shifts at weaning, a key developmental period for intestinal and immune health. We also show that this functional maturation of the gut microbiota is strongly influenced by maternal environment. Thus, targeting early life environmental factors is a promising strategy to program health trough the production of beneficial bacterial metabolites at the suckling-to-weaning transition.