1. College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
2. Engineering Laboratory of Sheep Breeding and Reproduction Biotechnology in Gansu Province, Minqin, China
3. The State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
4. Linze County Animal Disease Prevention and Control Center of Gansu Province, Linze, China