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Vet Med (Auckl). 2019 Nov 13;10:151-158. doi: 10.2147/VMRR.S219740. eCollection 2019.

A Pilot Study To Evaluate The Effect Of A Novel Calcium And Vitamin D-Containing Oral Bolus On Serum Calcium Levels In Holstein Dairy Cows Following Parturition.

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Agricultural Communications and Epidemiological Research (ACER) Consulting, Guelph, Ontario, Canada.
Heartland Veterinary Services, Listowel, Ontario, Canada.
Solvet Animal Health, Calgary, Alberta, Canada.



The initiation of lactation challenges the ability of the modern lactating cow to maintain calcium homeostasis, and typically results in a drop in blood calcium levels, leading to mobilization of calcium reserves from skeletal stores. As such, the recommendation to provide supplemental calcium at parturition to older cows has become an industry-standard practice.


Mature cows were treated at calving and 12 hrs later with either the novel calcium bolus (NB) or a commercially available calcium bolus (CB). Blood was collected from animals at 0, 1, 6, 12, 13, and 24 hrs following calving, and the resulting serum samples were analyzed.


Overall, there was no statistical difference between the NB and CB groups for blood calcium levels within the first 24 hrs following parturition (P = 0.50). Cows in both groups experienced a significant increase in serum calcium by 1 hr after parturition; however, this increase was not sustained through subsequent sampling times.


This pilot study demonstrates that both boluses have a similar effect in the elevation of blood calcium.


calcium supplementation; dairy cow; hypocalcemia; milk fever; parturition

Conflict of interest statement

The project was wholly funded by the sponsor, Solvet Inc. (Calgary, Alberta, Canada). DS, SR, RR, and RG received financial support from the sponsor for conducting the study, analyzing the data, and preparing the manuscript. MO is an employee of the sponsor. The authors have no other conflicts of interest to report.

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