1. Animal Science Department, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
2. Sheep Breeding Engineering Technology Center, Chinese Academy of Agricultural Sciences, Lanzhou 730050, China
3. Gansu Provincial Sheep Breeding Technology Extension Station, Sunan 734400, China
4. Centre for Tropical Livestock Genetics and Health (CTLGH), International Livestock Research Institute, Nairobi 00100, Kenya