This study was undertaken in 2013 and 2014 to investigate the seroprevalence of antibodies against foot-and-mouth disease vaccine (FMDV) in yaks, being core member of Bovidae living in the high-altitude mountains of China and adjacent countries. Results showed that serotype O FMDV elicited relatively higher antibody levels than Asia-1 in yaks. Either O or Asia-1 vaccine induced greater immunity in yaks in 2014 than that in 2013. Percentage of yaks acquiring effective antibody protection (over 50% protection) was 85.9% against type O and 74.2% against Asia-1 in 2013, and the level rose to 88.4 and 79.1% respectively in 2014. Additionally, FMDV immune efficacy in yaks from Qinghai and Sichuan provinces was greater than that in Tibet. This result indicated that yaks inhabiting the inland of China had better immune effect against FMDV vaccination than that in remote regions. In conclusion, FMDV elicits strong and significant antibody responses in yaks. However, immune discrepancies among yaks from different geographic areas existed after applying diverse FMDV serotypes on them. Further emphasis on the yak vaccination, especially with serotype FMDV Asia-1, is required in the remote areas of China like Tibet.

Key words: Asia-1, ELISA, FMDV, Serotype O, Yaks