Tomoaki Nakatani1* and Kazuo Sato2
1Department of Agricultural Economics, Hokkaido University, Kita9 Nishi9, Sapporo-shi, 060-8589, Hokkaido,
Japan. 2Department of Dairy Science, Rakuno Gakuen University, Midorimachi 582, Bunkyodai, Ebetsu-shi, 069-8501, Hokkaido, Japan.
