Association of increased serum acute-phase protein concentrations with reproductive performance in dairy cows with postpartum metritis

Background It is known that quantification of bovine acute-phase proteins could routinely provide early diagnostic and prognostic information for monitoring herd health status. Objective The aim of this study was to test the hypothesis that haptoglobin (Hp) and serum amyloid A (SAA) have the potential for indicating uterine infection, mainly due to subclinical endometritis, which can seriously influence the reproductive performance in dairy cows. Methods A total of 264 serum samples were collected from 24 Holstein dairy cows at defined intervals from 1 week prepartum to 6 months postpartum. Clinically healthy animals (Group 1, n=6) were compared with 24 animals having acute puerperal metritis (Group 2, n=18) and with concentrations obtained from healthy heifers (baseline values, n=10). The concentrations of serum Hp and SAA were measured using a hemoglobin-binding assay and Western blot analysis, respectively. Reproductive performance was assessed as the number of days open and the conception rate at the end of the study. Results Upper cut-off values for Hp and SAA concentrations in heifers were 130.9 mu g/L and 51.9 mu g/mL, respectively. Hp concentrations in Group 2 were significantly higher than those in Group 1 at all time points (P <.001). Additionally, among the successfully pregnant animals, the number of days open was significantly higher in 6 cows with Hp > 130.9 mu g/mL (median=316 days) than in 11 cows with Hp < 130.9 mu g/mL (median=120 days) (P=.0024). Conclusions Serum Hp and SAA concentrations can be used to recognize uterine infection in postpartum cows. The association between elevated Hp values and number of days open suggests Hp may also be a useful indicator of poor prognosis for reproductive performance.