1. Department of Animal Genetics and Breeding; National Engineering Laboratory for Animal Breeding; MOA Laboratory of Animal Genetics and Breeding; College of Animal Science and Technology; China Agricultural University; Beijing 100193 China
2. College of Agriculture; Hebei University of Engineering; Handan 056021 China
3. China Animal Disease Control Center; Beijing 100125 China
4. Hunan Institute of Animal Science and Veterinary Medicine; Hunan 410131 China
5. Institute of Quality Standards & Testing Technology for Agro-Products; Chinese Academy of Agricultural Sciences (CAAS); Beijing 100081 China