1. Shandong Provincial Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, PR China
2. College of Life Sciences, Shandong Normal University, Jinan, PR China
3. Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Taian, Shandong, PR China
4. Qingdao Agricultural University, Qingdao, PR China