1. Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, Shandong, China;
2. College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao, Shandong, China;
3. Reproductive Center, Weifang City People’s Hospital, Weifang, Shandong, China;
4. Department of Animal Sciences, Auburn University, Auburn, AL, USA