1. Department of Laboratory Animals, College of Animal Sciences, Jilin University, Changchun 130062, China
2. Experimental Testing Center, Jilin Agricultural Science and Technology University, Jilin 132101, China
3. Institute of Animal Husbandry, Xinjiang Academy of Animal Husbandry, Urumqi 830057, China
4. Yili Vocational and Technical College, Yili 835000, China
5. Department of Animal Science, Chungbuk National University, Cheongju 361-763, Republic of Korea