The Role of Milk Exosomal microRNAs in Balancing the Nutrition between Buffalo Breeds with Low and High Milk Production

Background: Milk is the primary nutrition source for mammalian infants. Production of milk varies among species, breeds within the same species or even individuals of the same breed. Despite large variations in milk production (e.g. yield, composition), the health of recipient infants remains unperturbed regardless of species, breeds or individuals, suggesting a compensatory mechanism for low milk production to offset the potential nutrition difference compared with high milk production. Methods: Here, we profiled and compared the milk exosomal microRNAs between groups with low and high milk production in two buffalo breeds. Result: We found that individuals with low milk production mainly down-regulated microRNAs targeting the genes in protein digestion and absorption pathway. Given that milk exosomal microRNAs could be taken up by the epithelial cells of infants, down-regulation of which inhibits expression of genes encoding proteins responsible for protein digestion, peptides and amino acid transportation in infants’ digestive system. Such down-regulation of genes facilitates the protein digestion, peptide absorption and amino acid absorption (e.g. stomach, intestine, colon) for infants. Our results thus provide a novel insight that exosomal microRNAs may play an important role in balancing the nutrient absorption of infants between mothers with low milk production and ones with high milk production.