1. College of Life Sciences, Hebei University , Baoding, China
2. Institute of Animal Sciences, Chinese Academy of Agricultural Sciences , Beijing, China
3. Animal Husbandry and Improved Breeds Work Station of Hebei Province , Shijiazhuang, China
4. Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison , Madison, Wisconsin, USA
5. Key Laboratory of Microbial Diversity Research and Application of Hebei Province, College of Life Science, Hebei University , Baoding, China