1. Division of Animal Life Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
2. Department of Animal Science, Graduate School of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan
3. Faculty of Agriculture, Saga University, Saga 840-8502, Japan
4. Kumamoto Prefectural Agriculture Research Center, Kumamoto 861-1113, Japan
5. Animal Breeding and Reproduction Research Division, Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Ibaraki 305-0901, Japan
6. Headquarters, National Agriculture and Food Research Organization, Ibaraki 305-8517, Japan