1. Livestock and Forage Research Division, Tohoku Agricultural Research Center, National Agriculture and Food Research Organization, Akahira 4, Shimokuriyagawa, Morioka, Iwate 020-0198, Japan.
2. BioEngineering, Nagaoka University of Technology, Kamitomioka-cho 1603-1, Nagaoka, Niigata 940-2188, Japan.
3. Faculty of Agriculture, Iwate University, Ueda 3-18-8, Morioka, Iwate 020-8550, Japan.
4. Western Region Agricultural Research Center, National Agriculture and Food Research Organization, Yoshinaga 60, Kawai-cho, Ohda, Shimane 694-0013, Japan.