Obihiro Uni.of Agri.and Veterinary Medicine,Inada-cho,Obihiro,Hokkaido,Japan,080-8555,E-mail:tsuji@obihiro.ac.jp;
Obihiro Uni.of Agri.and Veterinary Medicine,Inada-cho,Obihiro,Hokkaido,Japan,080-8555,E-mail:tsuji@obihiro.ac.jp;
Obihiro Uni.of Agri.and Veterinary Medicine,Inada-cho,Obihiro,Hokkaido,Japan,080-8555,E-mail:tsuji@obihiro.ac.jp;