Development of piglets' gut microbiota

Small-scale studies investigating the relationship between pigs' intestinal microbiota and growth performance have generated inconsistent results. We hypothesized that on farms under favorable environmental conditions (promoting sow nest-building behavior, high colostrum production, low incidence of diseases and minimal use of antimicrobials), piglet gut microbiota may develop towards a population that promotes growth and reduces pathogenic bacteria. Using 16S rRNA gene amplicon sequencing, we sampled and profiled the fecal microbiota from 170 individual piglets throughout suckling and post-weaning periods (in total 674 samples) to track gut microbiota development and the potential association with growth. During the suckling period the dominant genera were Lactobacillus and Bacteroides, the latter being gradually replaced by Clostridium sensu scricto 1 as piglets aged. We identified positive associations between the gut microbiota and average daily growth (ADG) of piglets in the nursery after weaning, but not during the suckling period. The relative abundances of SCFA-producing genera, in particular Faecalibacterium, Megasphaera, Mitsuokella and Subdoligranulum, significantly correlated with high ADG of weaned piglets. In addition, the succession of the gut microbiota in high ADG piglets occurred faster and stabilized sooner after weaning, whereas the gut microbiota of low ADG piglets continued to mature after weaning. Overall, our findings suggest that weaning is the major driver of gut microbiota variation in piglets with different levels of overall growth performance. This calls for further research to verify if promotion of specific gut microbiota, identified here at weaning transition, is beneficial for piglet growth.