Pinghua Li, Xingwen Bai, Pu Sun, Dong Li, Zengjun Lu, Yimei Cao, Yuanfang Fu, Huifang Bao, Yingli Chen, Baoxia Xie and Zaixin Liu*
* Corresponding author: Zaixin Liu liuzaixin3@hotmail.com
BMC Veterinary Research 2012, 8:57 doi:10.1186/1746-6148-8-57