Effects of tea polyphenols on intestinal barrier, antioxidant capacity, and caecal microbiota in lion-head geese
Tea polyphenols are natural bioactive compounds that have been associated with enhanced antioxidant capacity and improved gut health in poultry. This study evaluated the effects of dietary supplementation with tea polyphenols on intestinal morphology, barrier integrity, antioxidant status, and cecal microbiota in lion-head geese. In total, 240 one-day-old male lion-head geese were randomly assigned to 2 treatments: a basal diet (control) or the same diet supplemented with 1,000 mg/kg tea polyphenols (catechin purity, 50.4%) for 18 wk (6 replicates per treatment; 20 birds per replicate). Compared with the control, dietary tea polyphenol supplementation increased villus height and villus-to-crypt ratio (V/C) in the jejunum and ileum (P < 0.05) and reduced serum lipopolysaccharide (LPS) concentration (P < 0.05), whereas serum diamine oxidase (DAO) activity did not differ between groups (P > 0.05). In the jejunum, mRNA expression of ZO-1, Claudin-5, and Occludin was upregulated (P < 0.05); in the ileum, mRNA expression of ZO-1, Claudin-5, Occludin, and E-cadherin was upregulated (P < 0.05). Tea polyphenols increased jejunal total antioxidant capacity (T-AOC) and upregulated mRNA expression of GPX1, GPX2, HO-1, and Nrf2 (P < 0.05). In the ileum, tea polyphenols increased glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) activities, decreased malondialdehyde (MDA) content, and upregulated mRNA expression of SOD1, GPX1, GPX2, HO-1, and Nrf2 (P < 0.05). Metagenomic sequencing showed that, at the phylum level, the relative abundances of Firmicutes and Verrucomicrobia were lower in the tea polyphenol group (P < 0.05). At the genus level, tea polyphenols increased the relative abundances of Prevotella and Subdoligranulum and decreased those of Oscillibacter and Desulfovibrio (P < 0.05). Functional annotation (KEGG, eggNOG, and CAZy) indicated enrichment of carbohydrate transport and metabolism, glycosyltransferases (GT), and polysaccharide lyases (PL) in the tea polyphenol group. Overall, tea polyphenols promoted intestinal development, enhanced barrier- and antioxidant-related responses, and altered the composition and functional potential of the cecal microbiota, supporting improved gut health in lion-head geese.