1. Laboratory of Animal Breeding and Reproduction, Department of Animal Science, Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan
2. Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Hokkaido 060–0818, Japan
3. Laboratory of Animal Breeding and Reproduction, Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Fukuoka 812-8581, Japan