Impacts of seasonal housing and teat preparation on raw milk microbiota: a high-throughput sequencing study

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Accepted version
Date
2016-11-04
Authors
Doyle, Conor J.
Gleeson, David
O'Toole, Paul W.
Cotter, Paul D.
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American Society for Microbiology
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Abstract
In pasture-based systems, changes in dairy herd habitat due to seasonality results in the exposure of animals to different environmental niches. These niches contain distinct microbial communities that may be transferred to raw milk, with potentially important food quality and safety implications for milk producers. It is postulated that the extent to which these microorganisms are transferred could be limited by the inclusion of a teat preparation step prior to milking. High-throughput sequencing on a variety of microbial niches on farms was used to study the patterns of microbial movement through the dairy production chain and, in the process, to investigate the impact of seasonal housing and the inclusion/exclusion of a teat preparation regime on the raw milk microbiota from the same herd over two sampling periods, i.e., indoor and outdoor. Beta diversity and network analyses showed that environmental and milk microbiotas separated depending on whether they were sourced from an indoor or outdoor environment. Within these respective habitats, similarities between the milk microbiota and that of teat swab samples and, to a lesser extent, fecal samples were apparent. Indeed, SourceTracker identified the teat surface as the most significant source of contamination, with herd feces being the next most prevalent source of contamination. In milk from cows grazing outdoors, teat prep significantly increased the numbers of total bacteria present. In summary, sequence-based microbiota analysis identified possible sources of raw milk contamination and highlighted the influence of environment and farm management practices on the raw milk microbiota. IMPORTANCE: The composition of the raw milk microbiota is an important consideration from both a spoilage perspective and a food safety perspective and has implications for milk targeted for direct consumption and for downstream processing. Factors that influence contamination have been examined previously, primarily through the use of culture-based techniques. We describe here the extensive application of high-throughput DNA sequencing technologies to study the relationship between the milk production environment and the raw milk microbiota. The results show that the environment in which the herd was kept was the primary driver of the composition of the milk microbiota composition.
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Keywords
Farm practices , Food chain , Food safety , Metagenomics , Microbial source tracking , Raw milk microbiota
Citation
Doyle, C. J., Gleeson, D., O'Toole, P. W. and Cotter, P. D. (2017) 'Impacts of Seasonal Housing and Teat Preparation on Raw Milk Microbiota: a High-Throughput Sequencing Study', Applied and Environmental Microbiology, 83(2). doi:10.1128/aem.02694-16
Copyright
© 2016 American Society for Microbiology. All Rights Reserved. This is the Accepted manuscript version of the article published in its final form in Appl. Environ. Microbiol. doi: 10.1128/AEM.02694-16