Haptoglobin is an acute phase protein that is elevated in response to tissue damage and infections in dairy cows. The objectives of this study were to evaluate whether serum haptoglobin concentrations in the first week after calving can indicate disease status and severity, and whether haptoglobin concentrations are elevated before clinical signs of disorders or diseases are detected. Blood samples were taken from 161 Holstein cows (2 to 7 parities) at days -21 (-26 to -18), -14 (-17 to -11), -7 (-10 to -5), -3 (-4 or -3), -1 (-2 or -1), 0, 1, 3, 7, 14, 21, and 28 postpartum and analyzed for serum haptoglobin concentrations. Between days -21 and 100 postpartum, cows were monitored for signs of diseases and treated according to standard treatment protocols. Based on disease status and severity, cows were grouped into healthy cows (n = 20), cows with mild or subclinical disease (n = 41), cows with severe disease requiring antibiotics, glucose precursors, or both (n = 70), and cows that died or were sold within the first 100 d postpartum (n = 30). Haptoglobin areas and peak concentrations in the first week after calving were greater in sick versus healthy cows (P < 0.003) and in severely sick cows versus cows with mild or subclinical diseases (P < 0.001). Postpartal peak area and concentrations also differed or tended to differ between number and type of diseases (ketosis only, metritis only, mastitis only, other diseases only, 2 or more diseases). Based on the first treatment time, cows were grouped into not-treated cows (n = 40), cows first treated day 8 to 28 postpartum (n = 36), cows first treated day 4 to 7 postpartum (n = 32), cows first treated day 0 to 3 postpartum (n = 39), and cows first treated prepartum (n = 14). Prior to first treatment, sick cows had greater haptoglobin concentrations than not-treated cows (all P < 0.01). Cows with birth complications (twins, dystocia) had elevated haptoglobin concentrations two weeks before calving (P < 0.001). Our results suggest haptoglobin area and peak concentrations in the first week after calving can indicate disease status and severity and that elevated haptoglobin concentrations can precede birth complications and clinical onset of diseases during early lactation. Thus, serum haptoglobin concentrations may assist in early detection and treatment of sick cows.
Key Words: dairy cows, disease, haptoglobin, indicator.