The sow vaginal and gut microbiota associated with longevity and reproductive performance.

Background: Sow longevity and reproductivity are essential in the modern swine industry. Although many studies have focused on the genetic and genomic factors for selection, little is known about the associations between the microbiome and sows with longevity in reproduction.

Results: In this study, we collected and sequenced rectal and vaginal swabs from 48 sows, nine of which completed up to four parities (U4P group), exhibiting reproductive longevity. We first identified predictors of sow longevity in the rectum (e.g., Akkermansia) and vagina (e.g., Lactobacillus) of the U4P group using RandomForest in the early breeding stage of the first parity. Interestingly, these bacteria in the U4P group showed decreased predicted KEGG gene abundance involved in the biosynthesis of amino acids. Then, we tracked the longitudinal changes of the microbiome over four parities in the U4P sows. LEfSe analysis revealed parity-associated bacteria that existed in both the rectum and vagina (e.g., Streptococcus in Parity 1, Lactobacillus in Parity 2, Veillonella in Parity 4). We also identified patterns of bacterial change between the early breeding stage (d 0) and d 110, such as Streptococcus, which was decreased in all four parties. Furthermore, sows in the U4P group with longevity potential also showed better reproductive performance. Finally, we discovered bacterial predictors (e.g., Prevotellaceae NK3B31 group) for the total number of piglets born throughout the four parities in both the rectum and vagina.

Conclusions: This study highlights how the rectal and vaginal microbiome in sows with longevity in reproduction changes within four parities. The identification of parity-associated, pregnancy-related, and reproductive performance-correlated bacteria provides the foundation for targeted microbiome modulation to improve animal production.