1. Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Nasushiobara, Tochigi 329-2793, Japan
2. Department of Informatics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
3. Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki 305-0074, Japan
4. Research Center of Genetic Resources, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8602, Japan
5. Innovative Animal Production System, University of Tsukuba, 305-8571 Tsukuba, Japan