1. College of Animal Science, South China Agricultural University, Guangzhou, P.R. China
2. Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, P.R. China
3. South China Collaborative Innovation Centre for Poultry Disease Control and Product Safety, Guangzhou, P.R. China
4. Guangdong Vocational College of Science and Trade, Guangzhou, P.R. China
5. Department of Animal and Food Science, Oklahoma State University, Stillwater, OK, USA