1 Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences, Fuzhou, Fujian, China, and Fujian Animal Diseases Control Technology Development Center, Fuzhou, Fujian, China.
2 Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences, Fuzhou, Fujian, China, and Fujian Animal Diseases Control Technology Development Center, Fuzhou, Fujian, China Chensy58@163.com.