Dietary Proanthocyanidins Are Associated with Changes in the Fecal Microbiota and Serum Bile Acid Profiles of LPS-Challenged Weaned Piglets

Inflammatory stress can disrupt gut microbial communities and bile acid (BA) metabolism in weaned piglets; whether dietary proanthocyanidins (PACs) can alleviate such alterations remains unclear. Eighteen 21-day-old Duroc × Landrace barrows were randomly assigned to control (CON), lipopolysaccharide-challenged (LPS), and LPS-challenged PAC-supplemented (LPS + PAC; 250 mg/kg diet) groups for a 21-day trial. Fecal microbiota and serum BAs were assessed by 16S rRNA gene sequencing and targeted liquid chromatography–tandem mass spectrometry, respectively. LPS challenge increased the relative abundance of Fusobacteriota and enriched several taxa associated with inflammatory dysbiosis, including Proteobacteria, Enterobacteriaceae, and Escherichia-Shigella. Compared with the LPS group, PAC supplementation was associated with a lower relative abundance of Firmicutes and higher relative abundances of Mitsuokella and Dorea. LPS challenge reduced the serum concentrations of several primary and secondary BAs and increased the concentrations of sulfated BAs. PAC supplementation was associated with lower concentrations of several BAs but a higher glycoursodeoxycholic acid (GUDCA) concentration than LPS alone. GUDCA was negatively correlated with several LPS-enriched taxa. These findings indicate that PAC supplementation was associated with changes in selected fecal bacterial taxa and serum BA concentrations during LPS challenge. Whether these microbial and BA changes are causally related requires further investigation.