1. College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
2. Animal Health Supervision Institute of Biyang, Biyang, Henan, China
3. Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
4. College of Animal Science, Xinjiang Agriculture University, Urumqi, China