Dietary Full-Fat Rice Bran or Glucose Regulates Bile Acid Circulation, Colonic Microbiota, and Short-Chain Fatty Acids in Pigs During Chronic Cold Stress

Abstract

Chronic cold stress is a severe test that animals in cold regions have to face during winter. However, the lack of precise dietary adjustments for animals in cold regions represents a significant gap in addressing their nutritional needs. Full-fat rice bran is one of the feed materials rich in protein, lipids, dietary fiber, and antioxidant-active substances. Glucose is the most common quick energy supply. We determined dietary full-fat rice bran and glucose can improve the growth and health of cold-exposed pigs. A total of 18 Yorkshire pigs were randomized to one of three treatment groups (basal diet, full-fat rice bran diet (20%), and glucose diet (10%)) for 22 d to evaluate the effects of full-fat rice bran and glucose on growth performance, antioxidants, microbiomes, and bile acid circulation in cold-exposed pigs. The results showed that dietary full-fat rice bran decreased the average daily feed intake (p < 0.05), increased superoxide dismutase (SOD) activity in plasma (p < 0.05), and decreased Rikenellaceae_RC9_gut_group and Campylobacter in the colon microbiota of cold-exposed pigs (p < 0.05). Dietary glucose improved the growth performance of cold-exposed pigs and decreased the abundance of Prevotellaceae_NK3B31_group (p < 0.05) in the colon microbiota of cold-exposed pigs. Dietary full-fat rice bran and glucose both downregulated the abundance of Alloprevotella, Bradymonadales, and Erysipelotrichaceae in colon microbiota (p < 0.05), promoted the production of SCFAs, and activated the FXR-CYP7A1 signaling pathway. Dietary full-fat rice bran or glucose promoted fecal excretion of bile acids. This study demonstrated that dietary supplementation with full-fat rice bran or glucose can improve the colonic microbiota structure and SCFA levels in cold-exposed pigs. When comparing the two dietary strategies, the glucose-supplemented diet is more beneficial to the growth performance of cold-exposed pigs, while the full-fat-rice-bran-supplemented diet is more conducive to enhancing the function of their antioxidant system. Additionally, dietary supplementation with full-fat rice bran or glucose can also regulate the bile acid circulation in pigs, thereby enhancing their cold adaptation ability.