1. Key Laboratory of Animal Genetics, Breeding and Reproduction, Nei Mongol Autonomous Region, Hohhot 010018, People's Republic of China.
2. College of Animal Science and Medicine, Inner Mongolia Agricultural University, Hohhot 010018, People's Republic of China.
3. Laboratory of Animal Breeding and Reproduction, Faculty of Agriculture, Utsunomiya University, Utsunomiya 321-8505, Japan.