1. College of Animal Science and Veterinary Medicine; Shandong Agricultural University; Tai'an City Shandong Province 271018 People's Republic of China
2. Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention; Shandong Agricultural University; Tai'an City Shandong Province 271018 People's Republic of China
3. Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention; Shandong Agricultural University; Tai'an City Shandong Province 271018 People's Republic of China