Exploring the taxonomic content and diversity of the teat apex microbiome during a period of intramammary infection risk in organically raised heifers

Abstract

The primary objective of these studies was to investigate the relationship between the teat apex microbiome and postpartum intramammary infections in primiparous cows on organic dairy farms. Our study reported a higher prevalence and abundance of S. aureus DNA on the prepartum teat skin of heifers that later calved with a S. aureus IMI compared to cows that did not. In addition, we observed a higher prevalence of herpes virus DNA on the prepartum teat skin of heifers that calved with a S. aureus IMI compared to cows that did not. Together, these findings suggest that research into prepartum teat skin management strategies may be a promising avenue of further research that could help reduce the risk of both prepartum and postpartum S. aureus IMIs on organic farms. Our study also identified microorganisms on the teat apex that were associated with protection against postpartum IMIs, including both bacteria and bacteriophage. Interestingly, the prevalence and abundance of NAS was not significantly different among cows with an IMI compared to those without; however, continued research into the functional role of NAS within the teat apex microbiome is warranted given that many of the antimicrobial peptide genes that we identified in our study were encoded by NAS bacteria. Our study also found that the composition, diversity and structure of the teat apex microbiome was highly dynamic in primiparous cows during the prepartum and postpartum periods. While the dynamic nature of the teat apex microbiome was consistently observed across each of the five farms in our study, the dynamics tended to be unique to each farm, highlighting the need for future studies of the teat apex microbiome to consider farm-to-farm variability to properly contextualize microbiome results.