1. Department of Animal Science, National Chung-Hsing University, 250 Kao Kuang RD, Taichung, Taiwan 40227, Republic of China
2. College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
3. College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China.