The tiny bacteria breach herd health and spread like wildfire. Scours vaccines may be the solution to ending the bacteria epidemic, but it varies on one important component – timing.

The later the better

When it comes to vaccines, many people think the sooner the better, but that is not the case with scours vaccines. Russ Daly, an extension veterinarian from South Dakota State University, says it’s not too late to vaccinate for scours – actually, the later in pregnancy, the better.

“Scours vaccines work best when given later on in pregnancy,” Daly says. “They are not as effective if we give them early.”

For convenience sake, it is easy to administer scours vaccines during pregnancy-checking time, but that is part of the problem. When the vaccine is given in the early stages of pregnancy, it doesn’t work as effectively.

“The antibodies that form in her bloodstream, that would have been manufactured in response to a vaccine, usually don’t start to become part of the mother’s milk production, to enter the colostrum production, until very late in gestation,” Daly says.


“What we hope happens, is calves will drink good-enough quality colostrum and be protected by absorbing those antibodies.”

The calf receives the scours-fighting antibodies by drinking its mother’s colostrum in the early hours of life. Therefore, if the vaccine is given too early, the antibodies are gone before the colostrum is even created.

“It takes two weeks to get antibodies from bloodstream to colostrum,” says Zoetis Managing Veterinarian Jon Seeger. “Colostrum is made in the last month of pregnancy.”

Seeger suggests giving cows the scours vaccine six weeks before your maximum calf crop is going to be born. This practice will provide sufficient time for antibodies to go straight into the colostrum during its creation.

“The whole thing is trying to get the cow to have the most antibodies in her bloodstream at the time she is making colostrum,” Seeger says, “and rely on the calf to nurse and absorb one-third of that.”

Seeger refers to scours vaccines as a timing game because it’s all up to Mother Nature when the cow is going to calve. The rancher has to play a guessing game for their calves to receive that extra protection from their mother.

Southeastern Idaho rancher Steve Criddle noticed a significant difference in his herd since he started administering the vaccines later on in gestation.

“We really don’t have a scours problem since we started using the vaccines,” Criddle says. “We used to give them right after we shipped, but now we give them later on in the year.”Vaccinating for scours

Vaccine boosters

Since all cows don’t calve on day one of calving season, it’s very likely the vaccine will not be effective for a portion of the herd. Daly says if a herd is going through a scours outbreak, vaccine boosters are a safe and smart option to consider – even in the middle of calving season.

“It may seem kind of late to be doing this,” Daly says. “But vaccinating those cows left to calve is a good idea in order to help boost the level of antibodies.”

Every animal is different when it comes to calving. It’s important to reassure every cow has those scours-fighting antibodies, Seeger says. That is when boosters become very handy.

“If you think about it you probably missed the time for those late animals that were forming colostrum; you were way ahead of schedule,” Seeger says. “You want to stimulate those antibodies at the right time.”

With good cattle-handling procedures, Seeger says the vaccine booster is safe to give to late-calving cows. It will ensure calves receive a sufficient level of antibodies to fight scours and have a healthy start.

“It certainly makes sense to get a booster into those animals as soon as possible,” Daly says. “Their calves will benefit in the increased antibody level in the colostrum.”

Vaccines as a capstone

Vaccines play a significant prevention role in most operations, but for most vaccines to work effectively, a sustainable foundation must be in place first. Seeger warns, if vaccines are your only scours prevention plan – you are going to be disappointed.

According to Seeger, there are three things to always remember around calving season to prevent the scour bacteria from entering an operation: guarantee good herd nutrition and health, reconsider introducing new animals into the herd during calving season and then lastly, implement a vaccination program.

“Vaccination is a small part of the scours prevention program,” Seeger says. “It’s all about management, and vaccination can be used as a capstone to the program.”

Growing up, Criddle saw too many calves lost to scours and didn’t want to risk anything with his own cattle. He witnessed calves suffer due to lack of management, and he is adamant about keeping his herd healthy.

“I will not bring a Holstein in the herd,” Criddle says, “or any strange cows during calving.”

It makes sense that good nutrition and health for a herd is the first step to prevent scours, but an important thing to remember is the risk that is being taken when new cattle are introduced to the herd right before or during calving season.

“You really bring in new organisms,” Seeger says. “You are putting a higher threat level on your calving crop.”

Increased crowding and unclean calving areas also raise the possibility of scours greatly. When germs build up in an environment, calves are more likely to get sick with increased exposure.

Calving in clean areas is critical to ensure calves are not exposed to high levels of germs right off the bat.

“Make sure the cow concentration is managed,” Seeger says. “The more crowding, the more likely to have calf scours.”

To ensure a clean area, Criddle keeps his calving cattle separated into smaller bunches. Not only does this practice help with hygiene, it also inhibits scours from spreading through the herd. If it starts going through one group, it rarely spreads to another.

“That is why we put them in bunches,” Criddle says. “If one group is going through scours, I know I don’t have to worry about the other group.”

Not every producer will encounter a scours outbreak, but it’s serious enough that a yearly prevention plan is needed. It can damage a calf crop very quickly.

“I do everything to get those little guys to live,” Criddle says. “I hate watching them little buggers die.”  end mark

ILLUSTRATION: Illustration by Kristen Phillips.

Jamie Hawley