1. Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan 430070, P. R. China
2. College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
3. State Key Laboratory of Agriculture Microbiology, Huazhong Agricultural University, Wuhan 430070, P. R. China
4. The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, P. R. China
5. College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou 450046, P. R. China