1. Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China;
2. Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China;
3. Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China