The most effective time to vaccinate cows for reproductive disease is prior to the breeding season. If producers truly want to protect the developing fetus, cattle should be well vaccinated and immunity optimized before they become pregnant. It makes little sense to “boost” immunity half way through pregnancy because the opportunity has already been missed to protect the pregnancy. Vaccinating cattle challenges the animal’s immune system and prepares it for disease pathogens it may face in the future. In general, modified live vaccines (MLV) are more effective than killed vaccine in developing a broad immune response and are generally recommended.
Finding the correct window of opportunity to vaccinate cows postpartum and pre-breeding is difficult. Cows vaccinated shortly after calving can exhibit immunosuppression and vaccinations should be administered no earlier than two weeks postpartum, and some recommend waiting three or four weeks. Naïve cows – which are cows that have not previously been vaccinated for the disease – that are administered reproductive MLV can demonstrate temporary infertility that may interfere with breeding season and cause delayed pregnancy.
Some MLV have been approved for use on pregnant cows. Using these vaccines during the final trimester of pregnancy offers producers the opportunity to vaccinate cows with MLV within a reasonable time before breeding. Vaccinating pregnant cows requires that that the cow was vaccinated with the same vaccine within the past 12 months. Vaccinating naïve pregnant cows creates a high risk of vaccine-induced abortions. Since protocols involving vaccination of pregnant cows have become popular, vaccine-induced abortions have risen significantly.
To avoid problems related to abortion, delayed breeding and immunosuppression, producers need to find the appropriate window of opportunity to vaccinate cows between calving and breeding Cows that have been well vaccinated over time can be vaccinated within one to two weeks of breeding and can even be incorporated into an estrus synchronization program without reducing fertility. However, naïve cows require more time between vaccination and breeding to minimize delayed breeding problems. Vaccinations with MLV should be administered at least 30 days prior to breeding.
A good vaccination program starts with making sure replacement heifers (and bulls) have been well vaccinated. This makes it easier to find appropriate windows of opportunities for vaccination in mature cows. Replacements should be vaccinated against diseases specific to each individual farm with the consultation of a veterinarian and receive timely boosters. As part of a sound vaccination program, Michigan State University Extension recommends that replacement cattle generally receive their first reproductive vaccinations at six to eight months of age, receive a booster vaccination two to four weeks later and again prior to breeding season at 13 to 15 months of age. Developing a heifer’s immune system early and maintaining the system at a high level is the best defense against reproductive diseases. For more information contact me at firstname.lastname@example.org or 906-884-4386.