|Downey, Erika -|
|Mayes, M -|
|Tait, Jr, R -|
|Garrick, D -|
|Reecy, J -|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 2013
Publication Date: July 23, 2013
Citation: Downey, E.D., Mayes, M.S., Tait, Jr, R.G., Ridpath, J.F., Garrick, D.J., Reecy, J.M. 2013. An evaluation of circulating bovine diarrhea virus type 2 maternal antibody level and response to vaccination in Angus calves. Journal of Animal Science. 91:4440-4450. Interpretive Summary: Vaccination of calves is used to control infection with viruses that contribute to the development of respiratory disease. Frequently, vaccination programs start with the vaccination of young calves. A calf’s response to vaccination is affected by the level of antibodies it ingests via milk (passive antibodies) and the ability of its own immune system to respond to vaccination (active antibody production). The objective of this study was to examine factors, that can be controlled by animal management, that affect the levels of passive antibodies passed on to calves and the level of active antibody production achieved by calves following vaccination. To do this, researchers looked at antibodies in the serum of calves before and after vaccination that recognized bovine viral diarrhea viruses (BVDV). Despite the word diarrhea in the name BVDV, infection with these viruses is strongly associated with the development of respiratory disease. For this reason vaccination against BVDV is routinely performed by many producers. It was found that weaning at the time of vaccination as well as vaccinating in the face of high passive antibodies was both associated with a decrease in the calf’s ability to respond to vaccination. This information will be used to design better vaccination programs for young calves.
Technical Abstract: Vaccination against viruses has been shown to help prevent bovine respiratory disease in cattle. However, both passively acquired maternal antibody level and calf age have been shown to impact the ability of a calf’s immune system to respond to vaccination. The objectives of this study were to identify and evaluate environmental and management factors that affect 1) passively acquired BVDV type 2 antibody level, 2) rate of decline in passively acquired BVDV type 2 antibody level, and 3) response to BVDV type 2 vaccination. A two-shot modified live vaccine was administered to 1,004 Angus calves that were weaned at either the initial vaccination (n = 508) or the booster vaccination (n = 496). Bovine viral diarrhea virus type 2 antibodies were measured in serially collected serum samples in order to quantify antibody response to the vaccination. Calf age nested within birth year season and dam age significantly (P < 0.05) affected all traits evaluated. The level of circulating, passively acquired maternal antibodies present at the time of vaccination had a significant (P < 0.05) effect on antibody response to vaccination (initial, booster, and overall response), as well as final antibody level. Calves that were weaned at the time of initial vaccination had significantly (P < 0.05) higher final antibody levels and response to vaccination, compared to animals weaned at the time of booster vaccination. In order for a calf to mount an antibody response to vaccination, maternal antibodies in circulation need to be below a given threshold. However, the age at which a calf reached this threshold was dependent on dam age. Taken together, these factors influence the age at which to initiate a vaccination protocol to successfully mount an antibody response to vaccination.