1. Laboratory of Theriogenology, Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-cho Minami, Tottori 680-8553, Japan
2. Laboratory of Reproductive Physiology, Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan
3. United Graduate School of Veterinary Science, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8511, Japan
4. Laboratory of Veterinary Biochemistry, Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-cho Minami, Tottori 680-8553, Japan
5. Department of Genetics and Animal Breeding, Faculty of Animal Production, University of Khartoum, Shambat 13314, Sudan
6. Laboratory of Animal Physiology, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatuka-cho, Shobara, Hiroshima 727-0023, Japan