1. Sichuan Key Laboratory of Conservation Biology for Endangered Wildlife, Chengdu Research Base of Giant Panda Breeding, Chengdu, Sichuan, P. R. China
2. Morinyu Sunworld Co., Ltd., Minato-ku, Tokyo 108–0075, Japan
3. Department of Animal Sciences, Faculty of Life and Environmental Sciences, Teikyo University of Science, Adachi-ku, Tokyo 120–0045, Japan
4. Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252–0813, Japan