Age-induced changes in the oviductal microbiome of laying hens

Abstract

Introduction: The chicken's reproductive tract microbiome plays a vital role in egg production and ensures the egg's safety for human consumption. The microbiome influences the immune system in the reproductive tract to prevent the transmission of pathogens, like Salmonella or Staphylococcus, which can be passed through eggs and cause significant human health risks if consumed. Moreover, older hens experience a decline in immune function like humans. This immunosenescence may hinder their ability to maintain a healthy microbiome, leading to an increased risk of microbial imbalances and the colonization of pathogenic bacteria. The impact of aging on microbial diversity in the oviduct of hens is not well understood. This study aimed to identify the microbial communities present in the oviduct of laying hens from different age groups, to detect shifts that may impact reproductive health and egg quality. We hypothesize that the microbiome of the oviductal tract in laying hens undergoes distinct, age-related changes impacting egg production and safety. Methods: In this study, magnum and uterus mucosa samples were aseptically collected from the hens at the peak production phase (37 weeks of age), the mid-decline phase (67 weeks of age), and the decline production phase (87 weeks of age). After DNA extraction, 16S rRNA gene sequencing was conducted using an Illumina platform, and the microbial diversity was analyzed with bioinformatic tools. The microbial metabolic pathways were compared between groups. Raw data was analyzed with QIIME2 PICRUSt2, and STAMP v2 software.The level of significance was considered at P < 0.05. Results: The oviduct samples showed significant differences across age groups for alpha and beta diversity measurements. While all sections displayed the same core phyla, there were significant changes in relative abundance between ages in butyrate-producing taxa. In addition, the relative abundance of species Bacteroides barnesiae, associated with increased egg production, significantly decreased with age in the magnum. Metabolic microbiome profiling showed differences in microbial biosynthesis of amino acids between age groups that could impact albumen and eggshell formation. Conclusion: This study showed key differences in diversity measures in the microbial community of the oviduct with varying age and egg production levels. Further characterization of the microbial taxa will establish more of their functional roles and implications for egg quality and safety, including developing probiotic therapies to maintain reproductive health. Acknowledgements: Funded by USDA Multistate (2059R) grant provided by the CTAHR University of Hawaii at Manoa