1. College of Animal Science and Technology, Hebei Agricultural University, Baoding, PR China;
2. College of Life Science and Technology, Southwest Minzu University, Chengdu, China;
3. State Key Laboratory for Sheep Genetic Improvement and Healthy Production, Institute of Animal Husbandry and Veterinary, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi, China;
4. College of Food Science and Technology, Hebei Agricultural University, Baoding, PR China;
5. Animal Husbandry and Veterinary Research Institute of Tianjin, Tianjin, China;
6. Research Center of Cattle and Sheep Embryo Engineering Technique of Hebei Province, Baoding, PR China