Simple SummaryInactivated foot-and-mouth disease (FMD) vaccines are used to protect livestock against the FMD virus. However, adequate levels of antibodies to provide protection against the FMD virus cannot be rapidly produced and take a long time to develop. In this study, to solve the challenge presented by the low antibody formation following FMD vaccination in pigs, an ionic amino–zinc complex (Amino–Zn), which has high bioavailability and immunity-enhancing effects, was administered orally. The effect on the FMD vaccine structural protein (SP) antibody formation was evaluated. As a result, the FMD vaccine SP antibody titer and immune indicators (IFN-γ, IgA) were significantly higher in the FMD vaccine group administered with 0.2% Amino–Zn in the feed compared with the positive control group (FMD vaccine only) after the first and second vaccinations. These results demonstrated that administering Amino–Zn effectively improved the antibody titer induced by the FMD vaccine and the immunity of the piglets.AbstractFoot-and-mouth disease (FMD) is a highly contagious animal disease that occurs in cloven-hoofed animals including pigs. To prevent FMD, vaccines and adjuvants are routinely used to induce an immune response; however, it requires an extended period of time to produce sufficient antibodies to prevent viral infection. In this study, we evaluated the increased effectiveness of the FMD vaccine structural protein (SP) antibody by administrating the Amino–Zn adjuvant to 100 pigs from 3 test pig farms in their feed. The FMD vaccine antibody titer and immunological index were analyzed using an enzyme-linked immunosorbent assay (ELISA) kit, and the hematological and blood biochemical parameters were analyzed using an automatic blood analyzer. The titer of the FMD vaccine SP antibodies in the 0.2% Amino–Zn-administered group was significantly increased compared to that of the positive control group only injected with FMD vaccine at 4 weeks after the first vaccination and at 4, 8, and 16 weeks after the second vaccination (p< 0.05). The FMD vaccine SP antibody positive rate was 100% until shipment. The IFN-γ and IgA levels were significantly increased by Amino–Zn administration 4 weeks after the first vaccination and 4 weeks after the second vaccination (p< 0.05). On the other hand, serum AST, and CPK (p< 0.001) were significantly decreased by Amino–Zn administration. These results show that the administration of Amino–Zn is effective in enhancing the antibody titer and immunogenicity of the FMD vaccine and can be used as an oral adjuvant (OrAd) to prevent viral diseases, such as FMD.