Objective  Differentially expressed proteins (DEPs) in ovaries of yak s in pregnancy and postpartum anestrus were identified.

  Method  Ovarian tissues of 3 randomly selected yaks each in pregnancy or postpartum anestrus from a natural grazing herd in Huangyuan County, Qinghai Province were sampled for DEP identification by the TMT method.

  Result  Thirty-eight upregulated and 19 downregulated DEPs were found in the yaks. The COG analysis indicated the major functions of the proteins related to the production and transformation of energy, protein turnover, and amino acid transport and metabolism. The Go analysis showed that they were mainly annotated in the biological processes of metabolism and reproduction, associated with the cellular component including organelle cell components, and participated in molecular function including the molecular transport activity. Whereas KEGG revealed their involvements in 27 signaling pathways that included BK and P450scc in the ovarian steroid hormone production, GSH-P1, GSTA2, GST, and AST in the amino acid transport and protein metabolism, and PI3K in the PI3K-Akt apoptosis signaling.

  Conclusion  The current study identified specific DEPs in yak ovary, i.e., BK, P450scc, GSH-P1, GSTA2, GST, AST, and PI3K, that were closely related to the onset of anestrus in the animal.