Figure 1.

Temporal variation of serological titers against Actinobacillus pleuropneumoniae serotype 1 strain FMV 91-6514 as measured by an indirect enzyme-linked immunosorbent assay (ELISA) in both control and treated carrier pigs, as well as in sentinel animals, within both groups. The arrowhead indicates the time at which seeder pigs were placed in contact with the naive pigs to generate carrier animals. Treated carrier pigs received feed medicated with tilmicosin phosphate at 400 ppm from day 0 to day 30. Naive sentinel animals were introduced in both groups after the end of the tilmicosin treatment. OD — optical density.