[1] Hokkaido Univ, Dept Dis Control, Lab Expt Anim Sci, Grad Sch Vet Med, Sapporo, Hokkaido 0600818, Japan
[2] Hiroshima Univ, Lab Anim Breeding & Genet, Higashihiroshima, Hiroshima 7398528, Japan
[3] Livestock Improvement Assoc Japan Inc, Inst Anim Sci, Maebashi, Gumma 3710121, Japan