Research Summary - 4
Periparturient sequence of physiology surrounding dyscalcemia in multiparous Holstein dairy cows
| Date/Time: |
9/13/2025
14:15
|
| Author: |
Jackson A Seminara |
| Clinic: |
Cornell University |
| City, State, ZIP: |
Freeville, NY 13068 |
J. A. Seminara, BS
1
;
K. D. Bach, MS, VMD, PhD
1
;
S. Mann, DVM, PhD, DACVPM, DECBHM
1
;
K. R. K. Gottwald, BS
1
;
L. L. Hernandez, MS, PhD
2
;
J. A. A. McArt, DVM, PhD, DABVP
1
;
1Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14850
2Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI
Introduction:
Many cows fail to normalize their serum total calcium concentrations (tCa) appropriately after the ubiquitous tCa decline that occurs immediately following parturition. This subclinical condition known as dyscalcemia (DYS) is diagnostically defined as tCa ≤ 2.2 mmol/L (8.8 mg/dL) at 4 DIM and has been associated with poor production, impaired reproductive efficiency, depressed dry matter intake (DMI), reduced rumination times, increased risk of disease, and elevated early postpartum inflammation. The relationships between these processes are poorly understood, therefore, our objective in this prospective cohort study was to establish the sequence of physiology related to DYS. We hypothesized that postpartum DMI is the first process to become measurably abnormal, followed by a change in inflammation, calcium status, rumination times, and milk production in sequence.
Materials and methods:
We enrolled 45 multiparous Holsteins during fall 2024 at one research dairy in NY and followed them from 14 d prepartum through 14 DIM. Cows were housed in individual tie stalls. Daily DMI was recorded along with rumination time measured at 8 h increments. We collected blood samples at -14, -7, -3, and -1 d relative to parturition, every 8 h from parturition through 96 h postpartum (4 DIM) and again at 120 h, 168 h, 240 h, and 336 h postpartum (14 DIM). Milk yield data were recorded every 8 h from parturition through 14 DIM. No supplemental calcium was provided. Serum samples were analyzed for tCa and haptoglobin concentrations. Cows were classified as DYS (tCa ≤ 2.2 mmol/L; n = 12) or eucalcemic (EU; tCa > 2.2 mmol/L; n = 33) based on tCa at 96 h postpartum. Linear mixed effects models were fit for each outcome modeled as a function of DYS status and its interaction with time, accounting for the confounding effects of parity group (2, 3, or ≥4), previous lactation 305 d milk yield, and time of calving (morning, afternoon, or night), with a random effect of cow. Pre- and postpartum models were fit separately. A backwards stepwise elimination process was used to test and eliminate any interactions with time in prepartum models where P > 0.1 and was applied to postpartum models to evaluate calf weight, calving difficulty (twins, stillbirth, or calving ease ≥ 3/5) and interactions with time.
Results:
Though we did not detect any large differences between DYS and EU cows prepartum for any of our outcomes, we observed marked differences in temporal patterns of postpartum physiology associated with DYS. Dyscalcemic cows experienced depressed intake starting between 24 h and 48 h postpartum (mean [95% CI]; DYS: 16.3 kg/d [14.5 to 18.1 kg/d]; EU: 20.6 kg/d [19.5 to 21.7 kg/d]; P < 0.001), and reduced rumination times beginning at 32 h (DYS: 25 min/h [19 to 31 min/h]; EU: 36 min/h [32 to 40 min/h]; P = 0.003), followed by low tCa concentration beginning at 56 h (DYS: 2.01 mmol/L [1.92 to 2.11 mmol/L]; EU: 2.15 mmol/L [2.09 to 2.20 mmol/L]; P = 0.02), and finally elevated haptoglobin concentrations at 64 h (DYS: 0.63 g/L [0.45 to 0.88 g/L]; EU: 0.39 g/L [0.32 to 0.48 g/L]; P = 0.02). Milk production was reduced for DYS cows throughout 14 DIM, with DYS cows averaging 11.9 kg/milking (11.3 to 12.6 kg/milking) and EU cows averaging 13.2 kg/milking (12.8 to 13.6 kg/milking; P = 0.002).
Significance:
Though our study may have limited generalizability due to its single farm and seasonality setting, we have demonstrated that under controlled conditions early postpartum maladaptation begins in earnest with depressed feed intake and rumination shortly after calving. The fundamental sequence of physiology that we have established may be relevant clinically to help inform intervention strategies that might ameliorate associated negative downstream outcomes.
