During last few years, (here is an increasing interest in the use of oil-adjuvant Foot and Mouth disease (FMD) vaccines against the traditional aqueous vaccine. In the present study, seroconversion produced by a uadrivalent oil-adjuvanf FMD vaccine (containing inactivated O, A, C and Asia-1 antigens) in cattle was assessed over a period of one year. For this, twelve calves of four months of age were vaccinated with a commercial oil-adjuvanf FMD vaccine at four monfhs and nine months after

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... y vaccinafion. Serum neutralizing antibody titres against four virus types were assessed by Liquid Phase Blocking ELISA (LPB-ELISA) at monthly intervals. The mean antibody titres aftained protective level in fhe first month itself and were mainfained above protective level up to nine months following primary vaccinafion. Booster vaccination also produced significant response. The fall in mean titres during fifth month of study maybe attributed fo the immunosuppression due to an outbreak of FMD that occurred all over the state during that month. !t is observed that oiladjuvant vaccines produce satisfactory immunity in cattle for more than nine months.