Exploring the variations in intestinal microbial communities and metabolite profiles between heat-sensitive and heat-tolerant chickens through a comprehensive multi-omics approach

Heat stress (HS) compromises poultry health by disrupting intestinal integrity and microbiota homeostasis. This study compared heat stress-susceptible (HS-SUS) and heat stress-resistant (HS-RES) White Leghorn chickens under chronic cyclic HS (35±2°C, 8 h/day). HS-RES chickens demonstrated superior growth performance (increased weight gain, reduced feed conversion ratio), decreased oxidative damage (lower MDA), and attenuated inflammation (reduced IL-6/TNF-α). Intestinal barrier integrity was preserved in HS-RES, evidenced by intact villi and upregulated tight junction proteins (ZO-1, Claudin-1, Occludin). 16S rRNA sequencing revealed higher microbial richness in HS-RES with enriched beneficial taxa (Lactobacillus, Alistipes) and depleted pathogenic Erysipelatoclostridium. Metabolomics identified HS-RES-specific enrichment in lysine/riboflavin biosynthesis and anti-inflammatory pathways, strongly correlating with beneficial microbiota. Critically, Lactobacillus abundance positively correlated with α-tocopherol, while Alistipes associated with lysine/riboflavin metabolism. These results establish microbial-metabolite synergy as a core mechanism for HS resilience, informing probiotic strategies to enhance thermotolerance.