1. College of Life Sciences, Institute of Reproductive Sciences, Qingdao Agricultural University, Qingdao 266109, China
2. Animal Husbandry and Veterinary Station of Penglai City, Yantai 265600, China
3. Institute of Animal Sciences, Heilongjiang Academy of Agricultural Sciences, Harbin, Heilongjiang 150086, China
4. Department of Animal Sciences, Auburn University, Auburn, AL 36849, USA
5. Department of Biomedicine and Prevention, University of Rome ‘Tor Vergata’, Rome 00133, Italy