Small RNA-sq of dairy cow dry secretions

Six mature pregnant Holstein cows were sampled at the end of lactation, during the dry period, to obtain dry secretions. Sampling took place at 0, 3, 10, and 21 days after the end of lactation. Approximately 50 mL of milk or dry secretion was collected from two quarters from each cow at each time-point. Samples were centrifuged at 10,000 x g for 15 minutes at 4C. The floating milk fat pad was carefully removed and the skim milk/dry secretion was carefully decanted away from the somatic cell pellet. Skimmed milk/dry secretions stored at -20C until RNA extraction. Extracted RNA was stored at -80C until library preparation. Small RNAs were extracted from each sample, and high throughput sequencing was done in an Illumina 3000 sequencer.