1. DKK-Toa Yamagata Co., Yamagata 996-0053, Japan.
2. Cooperative Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
3. Institute of Livestock and Grassland Science, NARO, Tsukuba 305-0901, Japan.
4. Awaji Agricultural Technology Center, Minimi-Awaji 656-0442, Japan.
5. Department of Animal Resources Science, Dankook University, Cheonan 31116, Korea.