1. Division of Animal Sciences, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
2. Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
3. Gifu Prefectural Livestock Research Institute, Minokamo, Gifu 505-0037, Japan
4. Present: Faculty of Applied Biological Science, Gifu University, Gifu, Gifu 501-1193, Japan