1. Division of Animal Life Science, Institute of Symbiotic Science and Technology; Tokyo University of Agriculture and Technology; Fuchu Tokyo 183-8509 Japan
2. School of Veterinary Medicine; Azabu University; Sagamihara Kanagawa 229-8501 Japan
3. Tobu Zoo Park; Saitama 345-0831 Japan
4. Japan Food Research Laboratories; Tama Laboratory; Tama Tokyo 206-0025 Japan