1. College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, P. R. China
2. Sichuan Animal Science Academy, Chengdu, Sichuan, China
3. Animal Breeding and Genetics Key Laboratory of Sichuan Province, Chengdu, Sichuan, China
4. Research Academy of Animal Husbandry and Veterinary Medicine Sciences of Jilin Province, Changchun, China