Mulberry leaf powder alleviates fatty liver hemorrhagic syndrome in laying hens via the gut-liver axis and hepatic metabolic regulation.

This experiment was conducted to investigate the effects of mulberry leaf powder (MLP) on alleviating fatty liver hemorrhagic syndrome (FLHS) in laying hens. A total of 180 healthy 33-week-old Hy-Line Gray laying hens were randomly assigned to 3 groups, with 6 replicates per group and 10 chickens per replicate, and fed a basal diet (CON), high-energy-low-protein (HELP) diet (FLHS), and HELP + 5% MLP diet (MLP), respectively. The experiment lasted 56 days. Results showed that the HELP diet successfully induced FLHS, characterized by an increased liver index, hepatic steatosis, and oxidative stress (P < 0.05). MLP significantly alleviated FLHS-induced hepatic steatosis, and enhanced antioxidant capacity (superoxide dismutase, catalase, glutathione peroxidase, total antioxidant capacity, and glutathione) in serum and liver (P < 0.05). Transcriptomic analysis identified 102 differentially expressed genes, whose expression was increased by FLHS but reversed by MLP, including SREBF1, SLC27A4, PLIN2, ACOT13, APOA4, GLRX, and MSRB1, which mainly participate in lipid droplet dynamics and redox homeostasis. qRT-PCR confirmed that upregulated expression of lipogenic genes (such as FASN, ACACA, SCD, and ELOVL6) and the downregulated expression of oxidative stress-responsive genes (SOD1 and GPX1) in the FLHS group were normalized by MLP (P < 0.05), accompanied by increased expression of PPARα, CPT1A, and CD36 (P<0.05). 16S rRNA sequencing revealed that MLP reduced the abundance of Desulfovibrio, Rikenellaceae_RC9_gut_group, Intestinimonas, and Shuttleworthia, and enriched Faecalibacterium and Bifidobacterium in the cecum of FLHS laying hens (P < 0.05). Furthermore, MLP increased acetate, propionate, and butyrate levels, and decreased isobutyrate and isovalerate levels (P < 0.05). Correlation analysis showed that cecal acetate, propionate, butyrate, Faecalibacterium and Bifidobacterium were positively correlated with hepatic antioxidant enzyme activities (P < 0.05), and negatively correlated with hepatic lipogenic gene expression, hepatic lipid deposition and oxidative stress markers (P < 0.05). These findings indicated that MLP alleviated hepatic lipid metabolism disorders and oxidative stress in FLHS laying hens, which might be achieved by modulating gut microbiota structure and short-chain fatty acid production.