1. Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
2. Department of Theriogenology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
3. Present: Division of Preventive Veterinary Medicine, Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
4. Present: Department of Veterinary Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan