When a cow is in the chute for pregnancy checking, many cow-calf producers take advantage of the opportunity to perform other necessary procedures to get their cows ready for the winter and the subsequent calving season. For some producers, vaccinating cows is on this list of tasks, but South Dakota State University Extension veterinarian Russ Daly says this is not necessarily the best time.
There are two main disease categories for which most producers vaccinate cows, he says. One is to boost colostrum quality by vaccinating against calf scours organisms. The other is for infectious reproductive pathogens such as IBR, BVDV, leptospirosis and vibriosis.
Most vaccines against reproductive pathogens are labeled to be given prior to breeding. In some herds, however, management and labor constraints result in situations where preg-check time is the only chance to get the cows vaccinated. But Daly says most of the reproductive diseases we can vaccinate for can have substantial effects within the first two months of gestation or earlier. Vaccinating a spring-calving cow herd in November means that seven to eight months might elapse between vaccination and the beginning of the next breeding season. This is long enough for the vaccine’s effects to have waned, as peak immunity probably occurs within a couple weeks of vaccination and then slowly declines. For this reason, gestational reproductive vaccine programs lack optimal timing. Otherwise, Daly says, there is little downside to using reproductive vaccines during pregnancy, if using killed vaccines. Vaccinating the herd during gestation with a killed reproductive vaccine will probably provide the herd a better level of protection than not vaccinating at all.
Veterinarians traditionally have advised against giving modified-live IBR vaccines to pregnant cows, as the practice can result in abortions. However, some newer MLV vaccines now are labeled for use in pregnant cows, with the caveat that animals must have been properly vaccinated pre-breeding that year with the same MLV vaccine. Daly says, however, there is some evidence doing so could increase risk of abortions. Producers with questions about their vaccine program should consult with their veterinarian, he says.