1. Department of Sustainable Agriculture, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
2. Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada
3. The embryo, Nagamine, Kumamoto 861-8037, Japan
4. Kumamoto Dairy Cooperative Association, Toshima, Kumamoto 861-8041, Japan