Vaccination is the main strategy for control and prevention of FMD in developing countries by using the oil-adjuvant vaccines are used. The main objectives of the study were assessing the efficacy and safety of locally produced trivalent vaccine (Tri-Apthovac®) containing serotypes A, O and SAT2 under the field conditions. Vaccination of calves and adult cattle was carried out in four different farms in different governorates under different conditions. Vaccinated animals were observed for one week for any adverse post vaccination. In the study, 81 randomly representative animals belonging to 4 farms (16 from first farm, 20 from the second farm, 25 from the third farm and 20 from the fourth farm) were examined
using VNT before vaccination and 3 weeks after vaccination. The percent of positive animals to serotype O showed that 48.15% of animals had titer of 0.9 log10, 24.69% had titer of 1.2 log10, 16.05% had titer of 1.5 log10 and 11.11% had titer of 1.8 log10 before vaccination. Three weeks post vaccination 4.94% had titer of 1.2 log10, 14.81% had tier of 1.5 log10 and
80.25% reach the maximum titer (1.8 log10 ). The percent of positive animals to serotype A showed that 56.79% of animals had titer of 0.9 log10 and 29.63% had titer of 1.2 log10, 11.11% had titer of 1.5 log10 and 247% had titer of 1.8 log10 before vaccination. Three weeks post vaccination 2.47% had titer of 0.9, 9.88% had a titer of 1.2, 9. 88% had titer of 1.5 log10
and 77.77% reach the maximum titer (1.8 log10). The percent of positive animals to serotype SAT2 showed that 60.49% of animals had titer of 0.9 log10, 20.99% had titer of 1.2 log10, 7.41% had titer of 1.5 log10 and 11.11% had titer of 1.8 log10 before vaccination. Three weeks after vaccination 4.94% had a titer of 0.9, 8.64% had titer of 1.2, 9.88% had titer of 1.5 log10 and 76.54% reach the maximum titer (1.8 log10). Oil adjuvant vaccine can be used even inl presence of colostral antibodies or residual antibodies from previous vaccination or infection. Protective immunity of oil adjuvant vaccines develops after 3 weeks of vaccination and reaches the maximum level after 4 weeks.