Multi-omics analysis reveals maternal gut microbiota-derived short-chain fatty acids and progesterone are associated with offspring birth weight in sows

Introduction Piglet birth weight is a key determinant of preweaning survival and subsequent growth performance, yet the role of maternal gut microbiota in relation to offspring birth weight in sows remains incompletely characterized. This study aimed to investigate the association between maternal gut microbiota in late gestation and offspring birth weight in sows. Methods Fecal samples were collected from 260 Landrace × Yorkshire (LY) sows at gestation day 100, and sows were categorized into high birth weight (HBW; 1.41 ± 0.02 kg, 16.25 ± 0.25 piglets/litter, n = 59) and low birth weight (LBW; 1.07 ± 0.02 kg, 12.19 ± 0.22 piglets/litter, n = 52) groups based on the average birth weight of live-born piglets and live litter size. We performed 16S rRNA gene amplicon sequencing and fecal untargeted metabolomics, and quantified fecal short-chain fatty acids (SCFAs) and sex hormones. Results Compared with LBW sows, HBW sows showed distinct bacterial community profiles with higher relative abundances of multiple taxa linked to SCFAs production, including Ruminococcus , Oscillibacter , Parabacteroides , and Bacteroides ( p < 0.05). Untargeted metabolomics revealed a clear separation between groups and enrichment of pathways related to primary bile acid biosynthesis and steroid hormone biosynthesis in HBW sows ( p < 0.05). Consistently, fecal acetate ( p = 0.005), propionate ( p = 0.034), isobutyrate ( p = 0.007), valerate ( p = 0.036), as well as progesterone ( p = 0.016), were significantly higher in HBW sows, and these indices were also positively correlated with piglet birth weight. Spearman correlation analysis showed that gut bacterial taxa enriched in the HBW group were positively associated with primary bile acids and sex hormone-related metabolites, which were also positively correlated with piglet birth weight. Discussion In conclusion, these multi-omics data indicate that higher piglet birth weight is associated with an SCFAs-enriched gut microbial ecosystem accompanied by enhanced bile acid and steroid hormone-related fecal metabolic profiles during late gestation.