Responses of Intestinal Antioxidant Capacity, Morphology, Barrier Function, Immunity, and Microbial Diversity to Chlorogenic Acid in Late-Peak Laying Hens.

Simple Summary: The intestines of layers during the late laying phase usually exhibit lipid metabolism disorders, concurrent with impaired energy production and antioxidant capacity. Therefore, it is necessary to explore feed additives that can enhance production performance through preserving gut barrier integrity and balancing the microbiota. Chlorogenic acid (CGA) exhibits potent pharmacological effects, including antioxidant, anti-inflammatory, antibacterial, antiviral, and lipid metabolism-regulating properties. However, the impact of CGA on late-peak laying hens remains to be further studied. In this study, we investigated the effects of CGA on gut antioxidant status, morphology, barrier function, immunity, and cecal microbiota of late-peak laying hens. Our study provides evidence that CGA treatment can enhance intestinal antioxidant status, improve intestinal morphology, strengthen intestinal barrier and immune function, and promote beneficial gut microbiota growth in laying hens during the late-peak laying period. This study examined the influence of chlorogenic acid (CGA) on gut antioxidant status, morphology, barrier function, immunity, and cecal microbiota in late-peak laying hens. A total of 240 Hy-Line Brown hens, aged 43 weeks, were randomly assigned to four groups, the basal diet +0, 400, 600, and 800 mg/kg CGA, for 12 weeks. The results revealed that CGA significantly reduced ileal H2O2 and malondialdehyde levels; increased duodenal height, ileal villus height, and villus height-to-crypt depth ratio; while decreasing jejunal crypt depth. The 600 and 800 mg/kg CGA significantly upregulated the duodenal, jejunal, and ileal ZO-1 and occludin gene expression; increased IgG levels in serum and ileum; and upregulated ileal IgA gene expression. The 600 mg/kg CGA significantly upregulated CD3D and CD4 gene expression, while downregulating IL-1β gene expression in duodenum, jejunum, and ileum. Moreover, CGA changed the gut microbiota structure. The SCFA-producing bacteria unclassified_f__Peptostreptococcaceae, unclassified_f_Oscillospiraceae, Pseudoflavonifractor, Lachnospiraceae_FCS020_group, Oscillospira, Elusimicrobium, Eubacterium_ventriosum_group, Intestinimonas, and norank_f_Coriobacteriales_Incertae_Sedis were significantly enriched in the 400, 600, and/or 800 mg/kg CGA groups. The bacteria Lactobacillus, Bacillus, and Akkermansia were significantly enriched in the 600 mg/kg CGA group. Conclusively, dietary CGA (600–800 mg/kg) improved intestinal antioxidant status, morphology, barrier and immune function, and beneficial microbiota growth in late-peak laying hens. [ABSTRACT FROM AUTHOR]