[1] Hebei Agr Univ, Coll Anim Sci & Technol, Baoding, Peoples R China
[2] Swedish Univ Agr Sci, Dept Anim Nutr & Management, Uppsala, Sweden
[3] Swedish Univ Agr Sci, Dept Anim Breeding & Genet, Uppsala, Sweden
[4] Hebei Univ, Sch Basic Med Sci, Baoding, Hebei, Peoples R China