1. Graduate Institute of Veterinary Pathobiology, National Chung Hsing University, Taichung 402, Taiwan
2. Graduate Institute of Food Safety, National Chung Hsing University, Taichung 402, Taiwan
3. Research Center for Animal Medicine, National Chung Hsing University, Taichung 402, Taiwan
4. Department of Applied Science, National Taitung University, Taitung 950, Taiwan