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

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, <i>n</i> = 10) and low (LFCR, <i>n</i> = 10) FCR for analysis using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS). The microbiota analysis revealed significantly higher abundances of <i>Ruminococcus</i>, <i>Prevotella</i>, <i>Akkermansia</i>, and <i>Eubacterium</i> in LFCR pigs (<i>p</i> < 0.05), while pathogenic bacteria predominated in HFCR pigs (<i>p</i> < 0.05). LC-MS metabolomics identified significant variations in metabolites involved in steroid hormone biosynthesis and primary bile acid metabolism between the two groups (<i>p</i> < 0.05). Spearman correlation analysis further demonstrated significant positive correlations between <i>Ruminococcaceae_NK4A214_group</i> and <i>[Eubacterium]_coprostanogenes_group</i> with bile acid metabolites, as well as between <i>Akkermansia</i> and steroid hormone synthesis (<i>p</i> < 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).