1. Department of Animal Science; School of Veterinary Medicine; Kitasato University; Towada Aomori 034-8628 Japan
2. Milk Science Research Institute; Megmilk Snow Brand Co. Ltd.; Kawagoe Saitama 350-1165 Japan
3. Faculty of Veterinary Medicine; School of Veterinary Medicine; Kitasato University; Towada Aomori 034-8628 Japan