1. The Japan Racing Association, Tokyo 320-0856, Japan
2. Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880, Japan
3. College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea
4. Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima 890-0065, Japan
5. Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
6. Shadai Corporation, 275 Hayakitagenbu, Abira-cho, Yufutsu-gun, Hokkaido 059-1432, Japan
7. Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
8. Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan