EN
Prophylactic vaccination of cattle against foot-and-mouth disease (FMD), applied in many countries, revealed an insufficient post-vaccination immunity in young calves originating from cows vaccinated. A weak effect of vaccination observed in calves aged 2, 4 or even 6 months, was ascribed to the presence of neutralizing antibodies acquired by colostrum (3, 1, 2, 6, 7). Van Bekkum has found that even a low level of specific antibodies neutralized the effect of vaccine (1). The aim of the present work was to determine in calves the effect of passive immunity acquired by colostrum on the immunization process at use of the trivalent FMD vaccine, types A, C and O, by means of the seroneutralization (SN) test.