Reducing light exposure can increase the abundance of antibiotic resistance genes. Reducing light exposure can increase the abundance of antibiotic resistance genes in the cecum and feces

The gut microbiome is vital for health, influenced by factors like light exposure, yet its response in laying hens to intermittent light and its impact on antibiotic resistance genes (ARGs) remain unclear. In this study, we divided 20-week-old laying hens into two groups. These groups were exposed to either continuous normal light or intermittent light for 8 weeks. Feces and cecal contents were collected for analysis. Metagenomic analysis of both feces samples and cecal contents revealed notable shifts in microbial composition and the abundance of ARGs under intermittent light exposure (P < 0.05). Additionally, metabolomic analysis of the cecal contents revealed significant alterations in the abundance and composition of ARGs and MGEs with intermittent light exposure (P < 0.05). Network analysis demonstrated complex co-occurrence patterns among bacterial communities, metabolites and ARGs, especially noting correlations between Bacteroidetes species, ARGs, and metabolites. Despite observing differential associations in certain bacterial species, the number of ARGs and MGEs carried by dominant differential bacteria was relatively low, suggesting other bacterial communities may be more influential in ARG dissemination. Furthermore, we observed that metabolites serve as important mediators between bacterial communities and antibiotic resistance genes, offering new insights into the dynamics of antibiotic resistance formation. Our findings stress the impact of intermittent light on ARG proliferation in poultry farming and underscore the interconnectedness of ARGs, bacterial communities, and metabolites. This emphasizes the importance of considering both bacterial communities and metabolic pathways to comprehend antibiotic resistance in agricultural settings.