1. Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
2. Equine Department, Japan Racing Association, Tokyo, Japan
3. Miyazaki Yearling Training Farm, Japan Racing Association, Miyazaki, Japan
4. Equine Research Institute, Japan Racing Association, Tochigi, Japan
5. Laboratory of Veterinary Physiology, Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan