# Identification of Fecal Microbiota and Related Metabolites Associated with Feed Efficiency in DLY Pigs

## TL;DR

This study identifies gut microbes and metabolites linked to better feed efficiency in pigs, which could help improve breeding and reduce costs.

## Contribution

The study identifies specific gut microbes and metabolites associated with feed efficiency in pigs, offering new insights for targeted breeding strategies.

## Key findings

- Pigs with lower feed conversion ratios had higher abundances of beneficial bacteria like Ruminococcus, Prevotella, Akkermansia, and Eubacterium.
- Metabolite differences in steroid hormone biosynthesis and bile acid metabolism were observed between high and low feed efficiency pigs.
- Certain gut microbes correlated with bile acid metabolites and steroid hormone synthesis, suggesting their role in feed efficiency.

## Abstract

Improving feed efficiency (FE) is crucial for modern pig breeding due to its significant economic and environmental impacts. Fecal microbiota play a critical role in this by synthesizing various beneficial substances that enhance FE. This study utilized 16S rRNA gene sequencing and LC-MS to analyze microbial and metabolic differences between pigs with high and low feed conversion ratios (FCR). Results indicated that pigs with lower FCR had an increased abundance of beneficial SCFA-producing bacteria, while higher-FCR pigs exhibited greater levels of pathogenic taxa. These findings highlight microbial and metabolic contributions to feed efficiency and provide insights into targeted breeding strategies.

Improving feed efficiency (FE) is essential for enhancing productivity, reducing production costs, and minimizing environmental impacts in the swine industry. Fecal microbiota and their metabolites play important roles in nutrient metabolism and energy utilization. This study aimed to investigate the fecal microbiota and associated metabolites in pigs with divergent feed conversion ratios (FCR). Fecal samples were collected from 20 Duroc × (Landrace × Yorkshire) (DLY) commercial pigs exhibiting extremely high (HFCR, n = 10) and low (LFCR, n = 10) FCR for analysis using 16S rRNA gene sequencing and liquid chromatography–mass spectrometry (LC-MS). The microbiota analysis revealed significantly higher abundances of Ruminococcus, Prevotella, Akkermansia, and Eubacterium in LFCR pigs (p < 0.05), while pathogenic bacteria predominated in HFCR pigs (p < 0.05). LC-MS metabolomics identified significant variations in metabolites involved in steroid hormone biosynthesis and primary bile acid metabolism between the two groups (p < 0.05). Spearman correlation analysis further demonstrated significant positive correlations between Ruminococcaceae_NK4A214_group and [Eubacterium]_coprostanogenes_group with bile acid metabolites, as well as between Akkermansia and steroid hormone synthesis (p < 0.05). These findings suggest a potential role for specific microbes and metabolites that are associated with feed efficiency, and warrant validation in pig feeding trials and fecal microbiota transplantation (FMT).