Developing replacement heifers is costly. It takes time and money invested before you get any return from that young cow, so you don’t want to risk having many of them fall out of the program. Good health is paramount, so it’s important to help your replacement heifers start building immunity to common diseases before they enter the cow herd.

Chris Chase, a veterinarian within the Department of Veterinary and Biomedical Sciences at South Dakota State University, says vaccination should begin at a young age — while they are still on the cow, and again around weaning.

Chase says he’s not a fan of vaccinating for bovine viral diarrhea (BVD) when cattle are really young, however.

“Some people do it at branding time, when calves are getting their clostridial vaccine for blackleg, etc.,” he notes. “If calves are still quite young, however, there might be interference from maternal antibodies — especially if you are using modified-live virus (MLV) vaccine for IBR-BVD.”

A 2-month-old calf has a better chance at developing immunity than a 2-week-old calf, he adds.

“I recommend vaccinating heifers a couple times with modified-live IBR-BVD vaccine — one dose before they are 5 months old, and another dose a few months later,” Chase says, noting the second dose could come at weaning. “We need to have at least one of those vaccinations create good immunity.”

Typically, the MLV vaccine does a good job with one dose.

“If there is already good active immunity, the calf won’t need a booster, but it won’t hurt,” he says. If, however, a calf didn’t mount immunity with the first dose, the second one may do the job. You definitely want adequate immunity in replacement heifers before they go into the breeding herd.

“The reason we give two doses is that on any given day only about 70% to 80% of the calves actually gain good immunity from vaccination.” — Chris Chase

“The reason we give two doses is that on any given day only about 70% to 80% of the calves actually gain good immunity from vaccination,” Chase explains. “Some won’t, depending on the weather and any other stressors. If we get two doses into those calves, any that did not respond adequately to the first dose will have a chance to respond to the second.”

It’s crucial to have good immunity well ahead of breeding.

“One of the things we worry about, especially with heifers, is that the IBR (infectious bovine rhinotracheitis) component of the MLV vaccine can possibly interfere with conception if given too close to breeding,” Chase says, explaining it can cause short cycling. “If the heifers were completely naïve, with no immunity, vaccinating too close to breeding can cut down the conception rate; but, if they are already well-vaccinated as calves, with prior immunity, they will do better.”

Prebreeding vaccinations will include vaccinating against leptospirosis and sometimes another eight-way clostridial vaccine.

“I like to get those into them at least 60 days before breeding,” Chase says. “I want to get them set up as calves, and then the prebreeding vaccination will give them good immunity during pregnancy.”

“A killed vaccine can do a good job of protecting against IBR, but for BVD we need to use modified-live. After that, once those heifers have good immunity, we can booster with an inactivated vaccine,” he says. “If we give the lepto and viral vaccines about 60 days before breeding, this gives them three cycles before you synchronize them for breeding, and they will be in better shape to conceive. If you do it closer up, like 30 days, research shows that first-service conception rate could be as much as 8% or 9% lower.”

Those that don’t conceive may catch up and breed later, but then they will calve later. You want heifers to calve early for their first calf, since it takes them longer than cows to recover and rebreed — and you don’t want them coming up open the next year or calving late again.

When you go to all the expense and trouble to develop heifers properly, to have as many of them conceive as possible and not have any disease issues, you don’t want to “blow it” by poor timing of vaccination causing a lower conception rate!

Editor’s note: Heather Smith Thomas is a freelance writer and cattlewoman from Salmon, Idaho.

Angus Beef Bulletin EXTRA, Vol. 16, No. 9-A