When implementing a fall vaccination program for a cow herd, Grant Dewell, Iowa State University Extension beef veterinarian, and Chris Clark, ISU Extension beef program specialist, say it's important to keep in mind long-term goals, short term needs, and herd reproductive status.
"Implementing a health program that can achieve its goals is more important than using products because of convenience," they note in a recent Growing Beef newsletter offered by the Iowa Beef Center.
According to Dewell and Clark, there are many vaccines available that can be given to pregnant cows under certain conditions, but there is always some risk to the fetus. They recommend starting a health program for cows pre-breeding, when there is not a fetal risk.
Fall vaccines can offer short term protection until a pre-breeding program is fully established, they add.
Modified-live versus killed vaccines
On the debate about using modified-live versus killed vaccines during pregnancy, Clark and Dewell say MLV vaccines tend to give a more complete immune response but can also cause abortions. However, there are some MLV vaccines approved for pregnant cows as long as cows have been vaccinated within the previous 12 months with the same vaccine.
Killed vaccines, meanwhile, are safer but may not provide the same degree of protection. They recommend producers discuss the benefits and risks with a veterinarian before making a decision.
Lepto and scours
Fall also is an ideal time to vaccinate cows against lepto, the specialists say. Most pre-breeding vaccines include a 5-way lepto, but duration of immunity is limited. Lepto can cause mid- to late-term abortions in cows, so fall is the perfect time to provide additional immunity.
Operations that incorporate some degree of confinement in winter should "seriously consider" a lepto booster, they said.
On, vaccines for scours, Clark and Dewell say they can be given in the fall but may need to be boosted in the spring. For optimum efficacy, scours vaccines should be given several weeks prior to calving, and the best timing to achieve colostral protection is to vaccinate two to 12 weeks before calving.
They also note that scours vaccines administered more than 16 weeks prior to calving probably have minimal impact on colostral antibody levels.