A Progressive Dairy reader recently asked: “Would vaccinating cows at dry-off for clostridium give passive immunity to calves to help them for the first week or so until they are vaccinated?” The simple answer is: “Yes.”
Let’s dive more into colostrogenesis, which is the process of making colostrum, to better understand why.
A pregnant cow starts moving antibodies from her bloodstream into the udder approximately five weeks before her due date. The udder itself doesn’t create antibodies but instead transports antibodies from the bloodstream into the udder to create antibody-rich colostrum. Cattle do not transfer antibodies to their unborn calves through the placenta like humans do, so newborn calves absolutely require colostrum to be protected from disease.
When a cow is given an injectable vaccine, her immune system forms antibodies to the pathogens in the vaccine. It takes two to three weeks for antibody levels to peak in the bloodstream. If it is the first time an animal received a vaccine, or it has been more than a year since it was vaccinated, a second “booster” vaccine is often needed (especially if using a killed vaccine) to reach a protective level of antibodies. Thus, to optimize colostral antibody levels, pregnant cows should be vaccinated seven to eight weeks before their due date. If the cow has never been vaccinated before, she also needs an initial vaccine three to four weeks before that (so 11 to 12 weeks before her due date).
Since all the clostridial vaccines are killed vaccines, two doses are needed in heifers (the first dose at 11 to 12 weeks pre-fresh and the second dose at seven to eight weeks pre-fresh). Cows vaccinated in the previous year can typically receive a single clostridial vaccine at seven to eight weeks pre-fresh. Calves that receive colostrum from vaccinated cows should be protected against clostridia for two to 12 weeks, depending on the vaccine used. The benefit of vaccinating pregnant cows against clostridia is twofold: Calves receive higher colostral antibody levels, and cows are vaccinated against disease as well.
Consult your veterinarian to discuss optimal vaccine timing for your herd.
Note: These tips are in response to a question posed on the Progressive Dairy Twitter account. To submit questions for future Ask a Vet columns, please email inquiries to editor@progressivedairy.com, with subject, “Ask a Vet.”
