1. State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Animal Reproduction Institute, Guangxi University, Nanning, Guangxi, China.
2. Regenerative Bioscience Center, University of Georgia, Athens, Georgia.
3. Department of Animal and Dairy Science, University of Georgia, Athens, Georgia.
4. Department of Poultry Science, University of Georgia, Athens, Georgia.