IFNG and infection: Despite the well known poor sensitivity of diagnostic methods, including the culture of tissues generally considered the gold standard, to detect MAP infection, especially in the early stages of infection, the combination of methods used in this study provided evidence of exposure and infection in the majority of the challenged cattle by positive interferon-gamma release assay, fecal shedding, antibody ELISA, Map culture of intestinal tissues, gross and histological pathology lesion scoring.