Multi-omics Elucidates Gut Microbiota-Driven Mechanisms of Lipid Deposition in Pigs Fed a DDGS Diet

Abstract:
Background: Corn dried distillers’ grains with solubles (DDGS) is a cost-effective alternative feed ingredient in swine diets. However, its negative impact on carcass fat quality, characterized by increased polyunsaturated fatty acids (PUFAs) and reduced fat firmness, fundamentally limits its practical application. The underlying mechanisms, particularly the role of the gut microbiota in driving these changes, remain unexplored.
Results: Through a 55-day feeding trial with 30% dietary DDGS, integrated multi-omics analyses revealed that DDGS feeding reshaped the gut microbiome, elevating the abundance of species such as Ruminococcus_unclassified. Concomitantly, backfat transcriptomics showed DDGS downregulated lipid catabolism genes (e.g., LIPG, CEL) and upregulated a key gluconeogenic gene (PCK1). This host transcriptional reprogramming aligned with lipidomic profiles showing increased triglycerides (TGs) and ceramides but decreased glycerophospholipids (GPs). Crucially, antibiotic-mediated gut microbiota perturbation (DA group) reversed or mitigated these DDGS-induced changes: it attenuated the rise in PUFAs and TGs, restored GP levels, and altered the expression of key metabolic genes (e.g., FADS2, SCD5). Metagenomic analysis confirmed that DDGS reduced the microbial genetic potential for carbohydrate and lipid metabolism, a trend partially reversed by antibiotics. Correlation networks integrated differential microbes (e.g., Ruminococcus_unclassified), host genes, and lipids, delineating a potential microbial-host metabolic axis.
Conclusion: Our findings demonstrate that dietary DDGS remodels the porcine gut microbiota, which in turn reprograms host gene expression in adipose tissue, ultimately driving altered lipid deposition. The reversal of these effects upon microbial disruption provides direct evidence that the gut microbiota is an essential mediator of DDGS-induced metabolic phenotypes in finishing pigs. This study offers a novel, microbiota-centric perspective for understanding and potentially modulating the nutritional implications of alternative feed ingredients.