Research Summary - 1
Effect of one off-label calf diarrhea vaccination in pregnant and previously unvaccinated beef cows on calf serum antibody concentrations against E.coli K99, bovine rotavirus, and bovine coronavirus
| Date/Time: |
8/27/2026
16:30
|
| Author: |
Jake Eldridge |
| Clinic: |
NC State University |
| City, State, ZIP: |
Raleigh, NC 27607 |
J. Eldridge, DVM
1
;
D.M. Foster, DVM, DACVIM, PHD
1
;
M.C. Rahe, DVM, MPH, DACVP
1
;
K. Cirone, B.Sc., PhD
1
;
M.C. Windeyer, BSC, DVM, DVSc
2
;
L. Gamsjäger, Mag.med.vet, DACVIM, PhD
1
;
1Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC
2ACER Consulting, Guelph, ON, Canada
Introduction:
Maternal vaccination enhances neonatal immunity against neonatal calf diarrhea (NCD) pathogens, but the recommended two-dose protocol for previously unvaccinated cattle can be logistically challenging. The objective of this study was to evaluate the impact of a single prepartum NCD vaccination given to previously unvaccinated beef cows on antibody concentrations against Escherichia coli (E. coli) K99/F5, bovine rotavirus (BRoV), and bovine coronavirus (BCoV) in their calves.
Materials and methods:
Mature beef cows (n=239, ≥2 parity) from three North Carolina herds with no prior NCD vaccination history were randomly assigned to one of three groups: (1) ONEVAC, receiving a single 2 mL dose administered ~1-2 months pre-calving; (2) TWOVAC, receiving two doses at ~2-3 months and ~1-2 months pre-calving; or (3) NOVAC, receiving no vaccine. Cows not receiving vaccines were given saline to standardize handling. Cow blood samples were collected at enrollment and at calving, and calf blood samples were obtained at 1–3 days of age. Antibody concentrations against E. coli K99/F5, BRoV, and BCoV were measured via competitive ELISA and expressed as percent inhibition (PI). Calf serum immunoglobulin G (IgG) concentrations were measured by radial immunodiffusion to account for differences in colostrum consumption. Descriptive data was calculated as median +/- IQR and linear mixed regression models were built to assess treatment effects on antibody concentrations with farm as a random effect.
Results:
Serum samples from 127 calves were analyzed (ONEVAC n = 40; TWOVAC; n = 37; NOVAC n = 50). Sample attrition was primarily due to cows failing to calve within the window required by the predetermined study vaccination protocol.
At enrollment, cows had minimal E. coli K99/F5 antibodies but moderate BRoV and BCoV antibodies. Calves born to ONEVAC dams had significantly lower E. coli K99/F5 antibody concentrations compared to TWOVAC calves (61.7 ± 52.2 vs. 97.3 ± 0.54; p < 0.0001). However, calves in both vaccine groups had higher E. coli K99/F5 antibody concentrations than NOVAC calves (10.6 ± 5.9; p < 0.0001). In contrast, there were no differences between ONEVAC and TWOVAC groups for BCoV (97.3 ± 0.8 vs. 92.2± 0.9, p = 0.34) and BRoV (90.9 ± 10.2 vs. 94.5± 6.5, p = 0.37) antibodies, and both exceeded NOVAC calves (BCoV 70.2 ±39.0, BRoV 79.3 ± 25.9; p < 0.001).
Significance:
A single prepartum vaccine dose increased antibody concentrations against all three pathogens compared to unvaccinated cows. However, a second dose was required to maximize E. coli K99/F5 antibody responses. These findings support some flexibility in vaccination protocols for herds in which viral diarrhea pathogens predominate, while reinforcing the importance of a two-dose regimen when E. coli K99/F5 is a primary concern.
