1. Department of Bioproduction, Graduate School of Bioindustry, Tokyo University of Agriculture, Abashiri, Hokkaido 099-2493, Japan
2. NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo 156-8502, Japan
3. Animal Biotechnology Group, Animal Research Center, Hokkaido Research Organization, Shintoku, Hokkaido 081-0038, Japan
4. Dairy Cow Group, Daily Research Center, Hokkaido Research Organization, Nakashibetsu, Hokkaido 086-1135, Japan