Associations between serum haptoglobin concentration and peri- and postpartum disorders, milk yield, and reproductive performance in dairy cows

We determined the associations between serum haptoglobin concentration and peri- and postpartum disorders, milk yield, and reproductive performance in dairy cows. Furthermore, associations between haptoglobin and some blood metabolites were also investigated. We collected blood from 112 Holstein cows 1 week postpartum to measure serum haptoglobin and metabolite/enzyme (aspartate aminotransferase [AST], total bilirubin [T-bilirubin], total cholesterol [TCH], non-esterified fatty acids [NEFA], and β-hydroxybutyrate [BHBA]) concentrations. Cows were divided into two groups based on their haptoglobin concentrations: a low-HP group (<100 µg/mL, n = 72) and a high-HP group (>100 µg/mL, n = 40). The incidence of peri- and postpartum disorders (dystocia, retained placenta, metritis, and endometritis) was higher (P < 0.05-0.01) in the high-HP group than in the low-HP group, whereas milk yield during the first 2 months postpartum was lower (P < 0.05-0.01) in the high-HP group than in the low-HP group. Moreover, the probability of conception by 210 days postpartum was also lower (hazard ratio: 0.55; P < 0.05) in the high-HP group than in the low-HP group. Serum AST, T-bilirubin, NEFA, and BHBA concentrations were higher in the high-HP group than in the low-HP group (P < 0.05-0.01), whereas TCH concentration was lower (P < 0.01) in the high-HP group than in the low-HP group. In conclusion, our results indicate that high serum haptoglobin concentration 1 week postpartum was associated with a greater incidence of peri- and postpartum disorders, and reductions in milk yield and reproductive performance, in dairy cows. It was also associated with high serum AST, T-bilirubin, NEFA, and BHBA concentrations, but low TCH concentration.