Fig. 1.

Graphical illustration of the in vivo intramammary infection (IMI) model. Animals selected for paternal BTA 18 haplotypes favorable (Q, n = 18) or unfavorable (q, n = 18) for somatic cell count received intramammary challenge with Staphylococcus aureus1027 (n = 24) or Escherichia coli1303 (n = 12) for 96 or 24 h, respectively. During Staphylococcus aureus challenge, inoculation was performed in the hind left (HL) and hind right (HR) quarters, and the front left (FL) quarter served as a negative control inoculated with saline solution, while the front right (FR) quarter was not treated. During Escherichia coli challenge, inoculation was performed with HR, saline solution was administered HL and front quarters were untreated. Clinical examination, udder examination and blood and milk sampling were performed every 12 h. The graphical illustration of the cow and the udder has been designed by Wolfram Petzl