Bile Acid Supplementation Reduced Hepatic Lipid Deposition and Modulated Bile Acid Metabolism and the Gut Microbiota in Weaned Piglets

Background: Early weaning may induce significant oxidative stress in piglets, potentially leading to hepatic lipid deposition and adversely affecting both metabolic health and growth.

Objectives: This study aimed to investigate the effect of bile acids (BA) supplementation on hepatic lipid metabolism in weaned piglets.

Method: Sixty-four 21-d-old weaned piglets [Duroc × (Landrace × Yorkshire); 8.21 ± 0.20 kg body weight] were randomly divided into 2 groups (8 pens per group, 2 castrated males and 2 females per pen). Piglets received either a control diet (CON) or CON supplemented with 500 mg BA per kilogram of diet (BA) for 14 d. Growth performance, hepatic lipid metabolism-related gene and protein expression, BA profiles in the liver and ileum, and ileal microbiota (16S ribosomal ribonucleic acid Sequencing) were determined. Data were analyzed using 2-tailed unpaired t-tests and Kruskal-Wallis tests.

Results: Compared to the CON group, the BA group showed significant reductions in serum triglycerides (TG), serum total Cholesterol, and hepatic TG (49.2%, 45.7%, and 40.7%, respectively; P < 0.05), alongside a 69.9% increase in serum high-density lipoprotein Cholesterol (P < 0.05). BA supplementation significantly downregulated hepatic lipogenesis-related genes and proteins but upregulated lipolysis-related genes (P < 0.05). Hepatic lipidomics showed that BA supplementation increased phosphatidylcholine (83.0%), whereas reducing triacylglycerols (84.9%), sphingomyelins (54.7%), and diacylglycerols (73.2%) (P < 0.05). BA supplementation significantly increased hepatic conjugated BA (54.2%), cholic acid (162%), chenodeoxycholic acid (270%), and the hepatic expression of farnesoid X receptor (57.0%), small heterodimer partner (73.7%), and oxysterol 7α-hydroxylase (110%) (P < 0.05). Additionally, BA supplementation significantly decreased the ileal abundance of Lactobacillus (14.38%) but increased the abundance of Clostridium_sensu_stricto_1 (447%) and Blautia (134%) (P < 0.05). Spearman's correlation analysis indicated that hepatic BAs and ileal microbiota had strong correlations with serum total Cholesterol and TG, hepatic TG, and lipogenesis-related genes.

Conclusions: Our results suggest that BA supplementation reduces hepatic lipid deposition in weaned piglets by modulating BA metabolism and gut microbiota composition.