# Unraveling the role of bacteria with heritable versus non-heritable relative abundance in the gut on boar semen quality

## TL;DR

This study explores how heritable gut bacteria in boars influence semen quality through short-chain fatty acids.

## Contribution

The study identifies heritable and non-heritable gut bacteria in boars and their distinct roles in semen quality via SCFAs mediation.

## Key findings

- 39 heritable and 91 non-heritable bacterial genera were identified in boar guts.
- Heritable bacteria contribute more to SCFAs and semen quality than non-heritable ones.
- 99 mediation links between bacteria, SCFAs, and semen traits were identified.

## Abstract

The relative abundance of some bacteria in the gut of pigs is heritable, suggesting that host genetics may recursively influence boar semen quality by affecting the composition and function of gut microbiota. Therefore, it is essential to elucidate the specific contributions of heritable versus non-heritable gut microbiota to semen quality traits.

Our study aimed to identify heritable and non-heritable bacterial taxa at the genus level in the boar gut and to predict their functions and respective contributions to semen quality traits. At the genus level, 39 heritable and 91 non-heritable bacterial taxa were identified. Functional analysis revealed that predicted microbial functions in both groups were primarily enriched in carbohydrate, nucleotide, and amino acid metabolism. We further analyzed the average microbiability of heritable and non-heritable bacteria on short-chain fatty acids (SCFAs) and semen quality traits. The relative abundance of heritable bacteria was found to contribute more to SCFAs levels and semen quality than non-heritable bacteria. Mediation analysis revealed that SCFAs could mediate the influence of the relative abundance of heritable bacteria on host phenotypes, identifying 99 significant genus-SCFAs-semen quality trait mediation links.

Our findings underscore the substantial role of the relative abundance of heritable gut bacteria in shaping porcine semen quality through SCFAs mediation. These results highlight the potential of targeted microbiome interventions to enhance reproductive traits in pigs.

The online version contains supplementary material available at 10.1186/s12711-025-00990-2.