1. Animal Breeding and Reproduction Division, National Institute of Livestock and Grassland Science, NARO, Ibaraki 305-0901, Japan
2. Ibaraki Prefectural North Livestock Hygiene Service Center, Ibaraki 310-0002, Japan
3. Research and Education Faculty, Kochi University, Kochi 783-8502, Japan
4. National Institute of Agrobiological Sciences, Ibaraki 305-8602, Japan
5. Ibaraki Prefectural Livestock Research Center, Ibaraki 315-0132, Japan
6. National Institute of Animal Health, NARO, Ibaraki 305-0856, Japan
7. Headquarters, National Agriculture and Food Research Organization, Ibaraki 305-8517, Japan