Metabolomic and metagenomic insights into WFBG-mediated regulation of gut microbiota and metabolism in broilers

The steady state of gut microbiota is a key factor in regulating the growth of broilers. The regulatory role of wet-fermented brewer's grains (WFBG) in broiler gut development and microbiota is still elusive. In this study, non-targeted metabolomics and 16S rRNA sequencing analysis were used to investigate the effects of WFBG supplementation on serum metabolites and gut microbiota in 42-day-old broilers. Serum metabolomic analysis identified 546 differentially expressed metabolites (DEMs), with GO and KEGG enrichment analyses showing that specific DEMs were enriched in intestinal development-related pathways, including phenylalanine, tyrosine, tryptophan biosynthesis, and alpha-linolenic acid metabolism. 16S rRNA sequencing analysis showed significant intergroup differences in the relative abundances of Ligilactobacillus, Olsenella, Erysipelatoclostridium, and Blautia at the genus level in broiler gut microbiota between the control and WFBG groups. Integrative analysis of 16S rRNA sequencing and non-targeted metabolomics demonstrated that bacterial genera including Streptococcus and Proteus were positively correlated with N6,N6-dimethyllysine and quercetin, while negatively associated with 18 DEMs, such as 4-methylbenzenesulfonic acid and deoxycholic acid derivatives. Furthermore, we identified potential biomarkers associated with intestinal development induced by 20% WFBG supplementation. Our findings suggest that the maximum recommended inclusion level of WFBG in broiler feed should not exceed 20%. This study provides novel insights into the molecular mechanisms underlying fiber utilization and intestinal maturation in broilers.

肠道菌群稳态是调控肉鸡生长的关键因素。湿发酵啤酒糟（wet-fermented brewer's grains, WFBG）对肉鸡肠道发育及菌群的调控作用仍有待阐明。本研究采用非靶向代谢组学与16S rRNA测序分析，探究了添加湿发酵啤酒糟对42日龄肉鸡血清代谢物及肠道菌群的影响。血清代谢组学分析共鉴定出546个差异表达代谢物（differentially expressed metabolites, DEMs），通过基因本体（Gene Ontology, GO）与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）富集分析发现，特定差异表达代谢物显著富集于肠道发育相关通路，包括苯丙氨酸、酪氨酸、色氨酸生物合成以及α-亚麻酸代谢途径。16S rRNA测序分析显示，对照组与湿发酵啤酒糟组肉鸡肠道菌群在属水平上，轻乳杆菌属（Ligilactobacillus）、奥氏菌属（Olsenella）、红梭菌属（Erysipelatoclostridium）及布劳特氏菌属（Blautia）的相对丰度存在显著组间差异。对16S rRNA测序与非靶向代谢组学数据进行整合分析后发现，包括链球菌属（Streptococcus）、变形杆菌属（Proteus）在内的细菌菌属与N6,N6-二甲基赖氨酸及槲皮素呈正相关，而与4-甲基苯磺酸、脱氧胆酸衍生物等18个差异表达代谢物呈负相关。此外，本研究鉴定出与20%湿发酵啤酒糟添加诱导的肠道发育相关的潜在生物标志物。研究结果表明，肉鸡饲料中湿发酵啤酒糟的最大推荐添加量不应超过20%。本研究为肉鸡纤维利用与肠道成熟的分子机制提供了全新视角。