1. Animal Products Research Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, Japan 305-0901
2. Animal Genome Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan 305-0901
3. Livestock Production and Wildlife Management Research Division, NARO Agricultural Research Center for Western Region, Ohda, Shimane, Japan 694-0013