Differences in the microRNAs Levels of Raw Milk from Dairy Cattle Raised under Extensive or Intensive Production Systems

SIMPLE SUMMARY: Extensive animal production systems are generally considered more sustainable and beneficial for the environment and for maintaining rural populations. However, there is no defined concept of what extensive milk production is. It is assumed to be a kind of production based on pasture and forage, with animals spending part of their daytime free and with a low stocking density. In order to increase consumer confidence in this type of product, we have studied markers based on molecules naturally present in the milk that allow us to differentiate the production system in which the cows that have produced the milk have come from. In addition, we are attempting to determine whether the milk production system can have benefits for consumer health. ABSTRACT: Studying microRNA (miRNAs) in certain agri-food products is attractive because (1) they have potential as biomarkers that may allow traceability and authentication of such products; and (2) they may reveal insights into the products’ functional potential. The present study evaluated differences in miRNAs levels in fat and cellular fractions of tank milk collected from commercial farms which employ extensive or intensive dairy production systems. We first sequenced miRNAs in three milk samples from each production system, and then validated miRNAs whose levels in the cellular and fat fraction differed significantly between the two production systems. To accomplish this, we used quantitative PCR with both fractions of tank milk samples from another 20 commercial farms. Differences in miRNAs were identified in fat fractions: overall levels of miRNAs, and, specifically, the levels of bta-mir-215, were higher in intensive systems than in extensive systems. Bovine mRNA targets for bta-miR-215 and their pathway analysis were performed. While the causes of these miRNAs differences remain to be elucidated, our results suggest that the type of production system could affect miRNAs levels and potential functionality of agri-food products of animal origin.