Journal article

Publication year: 2023

Pages: 2592-2602

Journal: Journal of Veterinary Internal Medicine

Volume number: 37

Issue number: 6

ISSN: 0891-6640

eISSN: 1939-1676

Open access status: Gold

DOI Link: https://doi.org/10.1111/jvim.16879

Publisher: Wiley

Abstract: 

Background: Diagnosis of subclinical hypocalcemia in cattle is based on concentration of total Ca ([TCa]) in serum or plasma below the reference range, with [TCa] serving as proxy for the concentration of ionized Ca ([iCa]).

Hypothesis/Objectives: To investigate the relation between [iCa] and [TCa] in periparturient cows over time, and its association with various metabolites.

Animals: Thirty periparturient dairy cows.

Methods: Prospective observational study. Blood from periparturient cows was obtained between 4 days before and 7 days after calving. Samples underwent blood gas analysis and blood biochemical analysis. The ratio of [iCa] : [TCa] was computed. Repeated measures linear regression analyses, spearman correlation-, Deming regression- and receiver operating characteristic (ROC) analyses were conducted.

Results: Correlations between [iCa] and [TCa] ranged from r = 0.55 to r = 0.84. The diagnostic value of [TCa] to identify cows with [iCa] below the arbitrary cut-off of 1.1 mmol/L was weak in particular during the first 24 hours of lactation, but continuously improved toward the end of the study with areas under the ROC curve increasing from 0.64 at d 0 to 0.93 at d +4 after calving. Strongest association with [iCa] : [TCa] were found for albumin (r(2) = 0.58, P < .0001), pCO(2) (r(2) = 0.45, P = .0003), the standard [HCO3] (r(2) = 0.22, P = .01), lactate (r(2) = 0.16, P = .04) and [NEFA] (r(2) = 0.15, P = .05).

Conclusion and Clinical Importance: The [TCa] is of limited value to identify cows with subnormal [iCa] in the first hours and days of lactation, a finding apparently attributable to the increased variation of a number of metabolic variables that affect the ratio of [iCa] : [TCa].

Harvard Citation style: Cohrs, I., Waechter, S., Golbeck, L. and Gruenberg, W. (2023) Evaluation of the relationship between ionized and total calcium concentrations in blood during the first week of lactation in dairy cows, Journal of Veterinary Internal Medicine, 37(6), pp. 2592-2602. https://doi.org/10.1111/jvim.16879

APA Citation style: Cohrs, I., Waechter, S., Golbeck, L., & Gruenberg, W. (2023). Evaluation of the relationship between ionized and total calcium concentrations in blood during the first week of lactation in dairy cows. Journal of Veterinary Internal Medicine. 37(6), 2592-2602. https://doi.org/10.1111/jvim.16879