1. Hubei Key Laboratory of Animal Embryo and Molecular Breeding, Wuhan 430070, PR China
2. Southeast Poultry Research Laboratory, Agricultural Research Services, US Department of Agriculture, Athens, GA 30605, USA
3. Institute of Animal Husbandry and Veterinary Sciences, Hubei Academy of Agricultural Sciences, Wuhan 430070, PR China
4. Veterinary Pathology Laboratory, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, PR China