1. Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian City, Shandong Province, China
2. Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China
3. Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian City, Shandong Province, China