1. Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Xianyang 712100, China
2. College of Life Sciences, Northwest A&F University, Xianyang 712100, China
3. Animal Disease Control Center of Haixi Mongolian and Tibetan Autonomous Prefecture, Delingha 817000, China
4. College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China