1. College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 625014, China
2. College of Animal Science, Xichang University, Xichang 615000, China
3. Livestock and Poultry Biological Products Key Laboratory of Sichuan Province, Sichuan Animal Science Academy, Chengdu 625014, China
4. Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu 625014, China