This study was established in order to investigate the effect of feeding of germanium biotite (GB) on the immune response of vaccinated calves to FMD trivalent oil vaccine. The study was carried out on two levels: an experimental level followed by field application level. Experimental level applied on 30 calves divided into six groups where group (1) was vaccinated with the trivalent oil FMD vaccine only while groups (2, 3, 4 and 5) were fed two weeks pre vaccination with 1, 2, 3 and 4 gram/100kgm body weight germanium biotite (% B.wt. GB) respectively and group (6) was left as a negative control group. The humoral response of calves were determined by serum neutralization test (SNT) and enzyme linked immunosorbent assay (ELISA) while the cellular immune response were detected by lymphocyte blastogenesis assay, phagocytic activity  beside estimation the level of interleukin 6 (IL-6) and IL-12. The protective antibody titer in the non-fed vaccinated group and the 1% B.wt. GB feed group extend till 32 weeks post vaccination, while in the 2% B.wt. GB feed group it was extended to 34 week post vaccination. The longest immune duration was achieved in the 3 and 4% B.wt. GB feed group as the protective antibodies extended till 36 week post vaccination. The results of cellular immunity showed the peak of lymphocyte blastogenesis and IL-6  appear earlier at 7 day post vaccination in 3% and 4% B.wt. GB feed groups than the other groups, the phagocytic percentage, phagocytic index and IL-12 peak was achieved earlier at 14 days post vaccination in 3% and 4% B.wt. GB feed groups than the other groups. There is no difference between the 3% and 4% B.wt. GB feeding groups. Field application on 50 calves feed on 3% B.wt. GB 2 weeks before vaccination with trivalent FMD oil vaccine confirm the above results. So it could be concluded that ingestion of GB has a potentiate effect on the immune response of cattle to the trivalent oil FMD vaccine providing high protective antibody levels of rapid onset and long duration when administrated 2 week pre-vaccination with a concentration 3% B.wt. GB.