Active Factors in the Adult Pig Colon: Microbial Transplantation Versus Supplementation with Metabolites in Weaned Piglets

The adult pig intestinal microbiota boosts piglet intestinal and microbiome development, thereby improving growth. However, the functional bacteria, metabolites, and their region-specific intestinal roles remain to be characterized. Administration of adult colon microbiota (CM; devoid of metabolites) to piglets promoted intestinal development post-weaning, as indicated by increased intestinal mucosal weight, villus-to-crypt ratio of the ileum (<i>p</i> < 0.05), and stimulated mucin secretion (<i>p</i> < 0.05). This effect was potentially mediated by modulating beneficial microbiota, including ASV50_<i>Prevotella</i> 7, ASV52_<i>Prevotella</i> 1, and ASV81_<i>Coprococcus</i> 1. Adult colon-derived microbiota was found to preferentially colonize the piglet colon, supported by significantly higher bacterial loads in colonic contents. Piglets receiving adult colon supernatant (CS; without bacterial cells) showed improved feed efficiency (FE; <i>p</i> < 0.05), with numerically higher body weight (BW) and average daily gain (ADG) compared to the control (CON) group. Additionally, CS transplantation (CST) promoted intestinal development, potentially by modulating abundances of beneficial bacteria species, including ASV95_<i>Turicibacter</i>, and ASV109_<i>Ruminococcaceae</i>, which correlated with increased production of antioxidant and anti-inflammatory chemicals, including protocatechuic acid (PCA, <i>p</i> < 0.01). Adult colon-derived microbiota and metabolites enhanced intestinal development in piglets. CS supplementation improved growth and immunity, mitigating post-weaning stress potentially through enriching growth-linked bacteria (e.g., <i>Turicibacter</i> and <i>Ruminococcaceae</i>) and metabolites production (e.g., prephenate and PCA). These findings highlight these functional microbiota and metabolites as promising direct-fed microbial or metabolite additives for piglet growth and intestinal health post-weaning.