Extraction of exosome RNA from yak and Jersey cattle-yak in June and December with reference to the instructions of Norgen 58000 kit. The experimental procedure was performed according to the standard steps provided by Illumina, including library preparation and sequencing experiments. Small RNA sequencing libraries were prepared using the TruSeq Small RNA Sample PrepKits (Illumina, San Diego, USA) kit. After library preparation, the constructed libraries were sequenced using Illumina instrument with a single-end 1X50bp read length.