Proximal and distal airway resistance. Calves were either challenged with 108 inclusion forming units of C. psittaci or sham inoculated (controls). Rdistal, distal airway resistance; Rproximal, proximal airway resistance. Data are expressed as Box-and-Whisker Plots representing lower and upper quartile values (box) with median and mean (+). Whiskers extend from each end of the box to the most extreme values within 1.5 interquartile ranges. Outliers are data beyond the ends of the whiskers. In calves inoculated with C. psittaci, # indicates a significant difference at the given time point compared to controls (Mann-Whitney-Wilcoxon W test) at a probability level of p ≤ 0.05. In controls, arrows indicate significant decreases (↓) at the given time point compared to data assessed within the group −7 days ante inoculationem (a.i.) at a probability level of p ≤ 0.05 (ANOVA, post hoc test: Bonferroni's multiple comparison procedure).