Effects of intramammary infection with Newbould 305, Parent 3231, or Heba 3231 on cytokine and haptoglobin expression. Least square mean of the log-transformed values ± standard error of the area under the curve for A) serum IL-8, B) serum IFN-γ, C) serum TGF-β, and D) milk IFN-γ on days 1-6 pi are shown. Least square mean of the log-transformed values ± standard error are shown for day 14 and day 21 pi. Significantly increased or decreased cytokine levels relative to baseline (day 0) values are denoted by asterisks (P < 0.05* and P < 0.01**). a,b indicate significant differences in cytokine levels between treatment groups (P < 0.05). E) Serum haptoglobin least square mean of log-transformed values ± standard error. Significant changes in serum haptoglobin concentration occurred over time for each challenge group (P < 0.01), but not at any individual time point, and no significant treatment differences were observed.