Water extract of Artemisia capillaris alleviates fatty liver hemorrhagic syndrome in laying hens by modulating the gut microbiota–bile acid axis

Fatty liver hemorrhagic syndrome (FLHS) is a major metabolic disorder that compromises the health and productivity of laying hens. This study aimed to evaluate the protective effects of the water extract of Artemisia capillaris (ACTE) against FLHS induced by a high-energy, low-protein (HELP) diet in laying hens. Ninety 50-wk-old Hy-Line Brown laying hens were randomly assigned to 5 groups: CON, HELP, HELP-L, HELP-M, and HELP-H, each with 6 replicates of 3 hens. ACTE supplementation alleviated metabolic disturbances induced by the HELP diet, improving production performance, reducing hepatic and abdominal lipid accumulation, and ameliorating liver dysfunction, as evidenced by reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, with the high-dose treatment showing the most pronounced protective effects. ACTE also enhanced antioxidant capacity and suppressed inflammatory responses. Gene expression analysis revealed downregulation of lipogenic genes and upregulation of genes involved in fatty acid oxidation and bile acid signaling. Ileal 16S rRNA gene sequencing showed that the HELP diet decreased microbial α-diversity, reduced the abundance of Lactobacillus, and enriched dysbiosis-associated genera, including Romboutsia and Clostridium sensu stricto 1. ACTE supplementation partially restored microbial community structure and increased Lactobacillus abundance. Targeted bile acid metabolomics further demonstrated increased primary bile acids, including cholic acid (CA) and chenodeoxycholic acid (CDCA), and decreased secondary and conjugated bile acids, including taurodeoxycholic acid (TDCA) and lithocholic acid (LCA). These findings suggest that ACTE supplementation mitigates FLHS associated with HELP diet feeding in laying hens by modulating lipid metabolism, oxidative stress, inflammation, gut microbiota composition, and bile acid homeostasis.