Evaluation of serum antibody responses in animals. At 14, 21 and 28 dpi, the IPMA assay was used to quantify L. intracellularis specific antibodies in serum of animals. A Percent of animals with antibodies in serum against L. intracellularis. B IPMA titer per treatment at different timepoints post-infection. Different letters indicate statistical significance (p < 0.05), error bars represent the standard error. No significant differences were found in IPMA titers between treatments but only between time points (p < 0.05).