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.

茶多酚（tea polyphenols）是一类天然生物活性化合物，已被证实可提升家禽的抗氧化能力并改善其肠道健康。本研究旨在评估日粮添加茶多酚对狮头鹅肠道形态、屏障完整性、抗氧化状态及盲肠微生物群的影响。试验共选取240只1日龄雄性狮头鹅，随机分为2组：基础日粮组（对照组），或在基础日粮中添加1000 mg/kg茶多酚（儿茶素纯度50.4%），试验周期为18周（每组设6个重复，每个重复20只鹅）。与对照组相比，日粮添加茶多酚可提升空肠和回肠的绒毛高度及绒毛隐窝比（V/C）（P<0.05），并降低血清脂多糖（lipopolysaccharide, LPS）浓度（P<0.05）；但两组血清二胺氧化酶（diamine oxidase, DAO）活性无显著差异（P>0.05）。空肠中，ZO-1、Claudin-5及Occludin的mRNA表达量显著上调（P<0.05）；回肠中，ZO-1、Claudin-5、Occludin及E-cadherin的mRNA表达量均显著上调（P<0.05）。茶多酚可提升空肠总抗氧化能力（total antioxidant capacity, T-AOC），并上调GPX1、GPX2、HO-1及Nrf2的mRNA表达量（P<0.05）。回肠中，茶多酚可提升谷胱甘肽过氧化物酶（glutathione peroxidase, GSH-Px）及总超氧化物歧化酶（total superoxide dismutase, T-SOD）活性，降低丙二醛（malondialdehyde, MDA）含量，并上调SOD1、GPX1、GPX2、HO-1及Nrf2的mRNA表达量（P<0.05）。宏基因组测序结果显示，在门水平上，茶多酚组的厚壁菌门（Firmicutes）和疣微菌门（Verrucomicrobia）的相对丰度显著降低（P<0.05）。在属水平上，茶多酚组的Prevotella及Subdoligranulum相对丰度显著提升，而Oscillibacter和Desulfovibrio的相对丰度显著降低（P<0.05）。功能注释（KEGG、eggNOG及CAZy）结果显示，茶多酚组显著富集了碳水化合物转运与代谢、糖基转移酶（glycosyltransferases, GT）及多糖裂解酶（polysaccharide lyases, PL）相关功能。综上，茶多酚可促进狮头鹅肠道发育，增强肠道屏障及抗氧化相关应答，并改变盲肠微生物群的组成与功能潜力，从而改善狮头鹅的肠道健康。