Multiple linear regression results presented in scatterplots for the iohexol serum concentrations of d 20 and the gut histologic parameters of d 21 (A, C, E, G). The bottom row (B, D, F, H) presents the association between the iohexol serum concentrations (d 21) and the gut histology (d 22). The strains (A, B, C) of the challenge groups are illustrated in different colors (blue = A = Hungary field strains, green = B = Netherlands field strains, yellow = C = Poland field strains) and a regression line illustrates the linear association between the gut histology (CD3+ (%), villus length, crypt depth and the villus-to-crypt ratio) and iohexol concentration. A significant association is observed between the iohexol concentration on d 20 and the gut morphology (villus length, crypt depth, villus-to-crypt ratio) on d 21 (A, C, E), but not between the iohexol gavage on d 21 and the gut histology on d 22 (B, D, F). The CD3+ (%) on d 22 is only linked with the iohexol concentration on d 21 (H).