1. College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
2. Institute of Animal Husbandry Quality Standards, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, China
3. The State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
4. Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, China