When trying to save on the cost of drugs, some producers have cut out vaccinating for bovine respiratory syncytial virus, or BRSV. However, a field trial conducted on a 385-cow dairy shows that vaccinating for BRSV can improve milk production slightly in first-lactation animals and improve reproductive performance.
Outbreaks of severe BRSV are rare, which is why many producers drop it from their vaccination programs, says Victor Cortese, director of technical service at Pfizer Animal Health. The disease is the equivalent of the common cold in humans.
Cortese, Jim Ferguson and David Galligan, veterinarians at the University of Pennsylvania, introduced BRSV vaccination into a herd that had not been vaccinating any of its animals for the disease. Prior to freshening, half of the cows and heifers received two doses of a four-way product containing vaccines for infectious bovine rhinotracheitis (IBR), parainfluenza (P-3), bovine viral diarrhea (BVD) and for BRSV. The remaining half received a three-way vaccine for IBR, P-3 and BVD.
The first lactation heifers which received the four-way vaccine produced 3 pounds more milk per day than heifers which received the three-way vaccine in the first 21 days of lactation. No other differences in milk production were found between the groups. However, BRSV-vaccinated animals showed a significant improvement in reproductive performance. The table below shows the difference in conception after first breeding for the two groups of cows.
Although the authors caution that the results of the study can’t be extrapolated to every herd, it does show the potential value for vaccinating for BRSV.
Percent of cows pregnant after the first insemination
|3-way vaccine (No BRSV)||4-way vaccine (BRSV)|
|First lactation heifers||32.7||54.6|
|Second lactation cows||28.9||47.8|
Source: Journal of the American Veterinary Medicine Association, June 15, 1997.