Grad Student Competition
Associations of early postpartum inflammation measured at 2 DIM with metrics of lactational success
| Date/Time: |
9/12/2025
08:00
|
| Author: |
Jackson A Seminara |
| Clinic: |
Cornell University |
| City, State, ZIP: |
Freeville, NY 13068 |
J. A. Seminara, BS
1
;
J. A. A. McArt, DVM, PhD, DABVP
1
;
1Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14850
Introduction:
Dairy cows experience inflammation during the postpartum period as a normal response to parturition and the start of lactation. Though more severe inflammation has been associated with disease conditions, reduced reproductive success, and decreased production, diagnostic targets, thresholds and timepoints are not known. Characterized by total serum calcium concentrations [tCa] ≤ 8.8 mg/dL at 4 DIM, dyscalcemia is a condition also associated with impaired outcomes, and dyscalcemic cows experience elevated inflammation as early as 2 DIM. Therefore, our objective in this exploratory study was to evaluate the relationships between the inflammatory marker haptoglobin measured at 2 DIM and metrics of lactational success including milk production through 10 weeks in lactation, dyscalcemia incidence, and risk of herd removal within 60 DIM. We hypothesized that increased haptoglobin concentrations at 2 DIM would be associated with more negative outcomes across all assessed metrics.
Materials and methods:
This exploratory prospective cohort study was conducted using samples banked from a previously conducted field trial where blood was collected at 2 and 4 DIM from 266 multiparous Holstein cows on 2 farms in central NY and 2 farms in northern NY. Samples taken at 2 DIM were analyzed for haptoglobin concentrations and samples taken at 4 DIM were analyzed for tCa. Cows were identified as dyscalcemic (tCa ≤ 8.8 mg/dL) based on tCa at 4 DIM. Daily milk production records averaged by week through 10 weeks in lactation and herd removal events through 60 DIM were also collected. Linear mixed effects models were used to predict milk production over 10 weeks in lactation from haptoglobin concentrations at 2 DIM. These models included haptoglobin, week of lactation, and their interaction, as well as parity group (2, 3, or ≥4), farm and a random effect of cow. Quasi-Poisson regressions, also known as robust Poisson models, were used to predict dyscalcemia risk and risk of herd removal through 60 DIM from haptoglobin concentrations at 2 DIM independently. Both models included haptoglobin and its quadratic term, parity group, and farm as covariates. Marginal means for milk production, and risk ratios for dyscalcemia and herd removal were predicted at three concentrations of haptoglobin corresponding to low (0.4 g/L; LO), intermediate (1.1 g/L; MED), and high (1.6 g/L; HI) levels of inflammation. Pairwise comparisons were conducted adjusting for multiple comparisons using the Tukey method.
Results:
Cows with higher concentrations of haptoglobin produced less milk per day on average over the entire 10 weeks of lactation (P < 0.001). Cows with LO inflammatory status produced 49.1 kg/d (95% confidence interval [CI]: 48.0 to 50.2 kg/d) on average while MED cows produced 47.2 kg/d (95% CI: 46.1 to 48.3 kg/d) and HI cows produced 45.9 kg/d (95% CI: 44.2 to 47.5 kg/d). Increased concentrations of haptoglobin at 2 DIM were associated with increased risk of dyscalcemia (haptoglobin: P < 0.001; haptoglobin2: P < 0.001) such that the risk ratio between LO and MED was 3.4 (95% CI: 2.1 to 5.4; P < 0.001), between LO and HI was 5.0 (95% CI: 2.8 to 8.7; P < 0.001), and between MED and HI was 1.5 (95% CI: 1.2 to 1.8; P < 0.001). The risk of culling within 60 DIM was associated with haptoglobin (P = 0.05) and its quadratic term (P = 0.09), such that the risk ratio between LO and MED was 3.8 (95% CI: 0.8 to 19; P = 0.1), between LO and HI was 3.8 (95% CI: 0.6 to 24; P = 0.2), and between MED and HI was 1.0 (95% CI: 0.4 to 2.7; P ≈ 1).
Significance:
Though this study is exploratory in nature and may have been underpowered for certain outcomes, these data firmly suggest that more severe postpartum inflammation measured as early as 2 DIM is associated with reduced lactational success. This evidence supports the hypothesis that inflammatory markers may be of diagnostic relevance for identifying cows that are failing to thrive early in lactation.
