Shiyong Wen, Guifang Cao*, Tuya Bao, LanLing Cheng, Haijun Li*, Chenguang Du, Yong Tu, Qi Li, Ruizhen Jian, Pengwei Zhao and Wuriliga
* Corresponding authors: Guifang Cao guifangcao@hotmail.com - Haijun Li navy1973@163.com
BMC Veterinary Research 2012, 8:143 doi:10.1186/1746-6148-8-143