1. Laboratory of Animal Physiology, Tokyo University of Agriculture, 1-1, Sakuragaoka 1 chome, Setagaya-ku Tokyo, 156-8502, Japan
2. Japan Livestock Technology Association, 9-20 Yushima 3 chome, Bunkyo-ku, Tokyo, 113-0034, Japan
3. Equine Research Institute, Japan Racing Association, 321-4, Togami-cho, Utsunomiya, Tochigi, 320-0856, Japan