1. Animal Resource Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Ibaraki 319-0206, Japan
2. Division of Animal Sciences, National Institute of Agrobiological Sciences, Ibaraki 305-8602, Japan
3. Institute of Biotechnology, Vietnamese Academy of Science and Technology, Hanoi, Vietnam
4. Graduate School of Life and Environmental Science, University of Tsukuba, Ibaraki 305-8572, Japan
5. National Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Ibaraki 305-0901, Japan
6. Graduate School of Veterinary Medicine, Azabu University, Kanagawa 252-5201, Japan