1. Department of Bioproduction, Graduate School of Bioindustry, Tokyo University of Agriculture, Hokkaido 099-2493, Japan
2. Division of Animal Breeding and Reproduction Research, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Ibaraki 305-0901, Japan
3. Dairy Cow Group, Daily Research Center, Hokkaido Research Organization, Hokkaido 086-1135, Japan
4. Department of Advanced Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka 598-8531, Japan
5. Department of Bioproduction, Faculty of Bioindustry, Tokyo University of Agriculture, Hokkaido 099-2493, Japan
6. Animal Biotechnology Group, Animal Research Center, Hokkaido Research Organization, Hokkaido 081-0038, Japan