RNA isolation from the milk of dairy ewes for transcriptome analysis

Different diet regimens induce changes in milk composition. For example, linseed supplementation is a reliable feeding strategy to increase polyunsaturated fatty acid content in milk fat from sheep, improving milk quality and its nutraceutical value. The identification of genes regulating milk secretion by mammary glands is a key-step for identifying molecular bases of diet induced differences in milk composition. In this work we describe a method for isolation of RNA from sheep milk. In fact, the milk of dairy ewes contains somatic cells mostly derived by mammary glands. We collected milk from dairy ewes at 90 day of lactation and after 3 weeks of diet supplementation with extruded linseed. Milk somatic cells were isolated by centrifugation and RNAs were purified from these cells. To estimate reliability of this method we performed Illumina RNA sequencing and started an analysis of RNA synthesis.