Fermented Rice Bran Enhances Rabbit Meat Quality and Nutritional Value via Metabolic Reprogramming and Enriched Nutrient Profiles

Background: The valorization of sustainable feed ingredients such fermented de-oiled rice bran meal (FDRBM) is crucial; however, the molecular mechanisms driving its benefits remain unclear. This study addresses this gap by investigating FDRBM as a dietary substitute for maize in rabbits to determine its effects on meat quality and underlying gut–liver axis communication. Methods: In an eight-week trial, New Zealand White rabbits were assigned to a control diet or the basal diet with a 20% substitution of either unfermented de-oiled rice bran (UFDRBM) or FDRBM. Post-trial, the researchers analyzed carcass traits, meat quality, and nutritional composition. A multi-omics approach integrates gene expression data from the ileum and muscle with liver metabolomics to model coordinated biological responses. Results: Although growth performance was similar, the FDRBM diet significantly improved meat quality by enhancing water-holding capacity and increasing essential amino acids (p < 0.05). Mechanistically, these improvements were associated with the upregulation of genes associated with oxidative muscle fiber (Tnnc1) and lipid metabolism. Analysis of the gut–liver axis revealed that FDRBM enhanced ileum antioxidant capacity, which coincided with profound reprogramming of liver metabolism (p < 0.01 *), identifying C17-sphinganine as a differential metabolite. Conclusion: This study provides novel insights into the mode of action of FDRBM, suggesting that it enhances rabbit meat quality in part by modulating metabolic gene expression and is associated with coordinated molecular changes across the gut–liver axis.