Calf Vaccinations

 By Heather Smith Thomas.

Newborn calves gain temporary (passive) immunity from diseases when they ingest colostrum, since this “first milk” contains maternal antibodies.  After a few weeks or months this temporary protection wanes, however, and calves must build their own immunities.  Vaccinating calves at the proper time in their young lives can help protect them until weaning age.  Vaccinating too soon may not stimulate much immune response, if the calf still has maternal antibodies in his system.  These tend to interfere with building his own immunities; the body sees no need to respond.

Chris Chase, Department of Veterinary and Biomedical Sciences, South Dakota State University, says there are several considerations to keep in mind.  “When maternal antibody protection begins to wane, we can get good response to vaccinations by about three months of age.  It all depends on how much protection the calf received at birth (how much colostrum, how soon, for maximum absorption of antibodies, and how good it was).  In most herds, you won’t find 100% of calves fully protected; it’s more like 70 to 80%.  When developing calf vaccination programs, we need to know which disease problems are in the herd,” he says.

BRSV (Bovine Respiratory Syncytial Virus), for instance, will necessitate a different plan.  “BRSV is notorious for maternal interference that can last for a long time,” says Chase.  If the calf received antibodies against BRSV from colostrum, the calf may not gain much immunity from an injected vaccine (unless it is adjuvanted) until those maternal antibodies are gone from his system.

“Producers need a specific plan for their own situation.  There are many different protocols.  You might decide to give calves vaccinations for IBR/BVD, but in reality those two diseases are generally not an issue in young calves,” he says.  You need to be more concerned with these diseases as calves approach weaning age.  An early vaccination, however, can help “prime” the immune system so that the calf has better response to the second shot at weaning time.

David R. Smith, Epidemiologist and Beef Program Leader at Mississippi State University, says many producers may not think through the reasoning why they are giving vaccines, or when.  “You have your hands on calves at branding, so this is usually when people vaccinate.  That’s not necessarily bad, but we do need to think about the problems we are trying to solve,” he says.

“For most producers, the problem is calves getting sick after they are weaned, as they go into a backgrounding phase or feedlot.  What most people are doing by using calfhood vaccines is to stimulate some immunity to protect calves at weaning time,” he says.

Also, it’s standard practice to vaccinate against clostridial diseases (blackleg, malignant edema, redwater, gut infections caused by Clostridia perfringens, etc.) because these deadly diseases may be a risk to calves at any age.  “These are some of the diseases that can occur prior to weaning.   Calfhood diseases include blackleg and some of the other clostridial diseases like enterotoxemia (caused by several different types of C. perfringens), and pathogens that cause scours, along with respiratory diseases like pneumonia.  Each rancher needs to tailor a vaccine program to protect against the diseases that affect calves on his/her ranch,” says Smith.

“This may mean vaccinating cows prior to calving, to give calves instant temporary protection against certain types of scours.”  You can’t vaccinate the calves themselves quickly enough because they might ingest pathogens while nursing a dirty udder, or when born into a dirty environment at the same time they’re ingesting their first colostrum.  They wouldn’t have time to mount immune response from vaccinations, but the antibodies in colostrum can protect them.

“If you have scours problems in very young calves, you need to vaccinate the cow so she can give the calf immediate protection.  Some of the other problems are longer term.  For instance, we worry about blackleg all the way through the calf’s life, so we can vaccinate the calf at branding time or when putting a tag in soon after birth,” he says.

For respiratory disease, there is still debate about optimal age for vaccination, since calves in some herds get what has been termed “summer pneumonia” while they are still on the cow.   Thus it is important to work with your veterinarian to determine a vaccine strategy.  “In our study of summer pneumonia, about one herd out of five has problems on any given year.  Half the battle is figuring out when you can get your hands on the calves (or cows) to give vaccines.  The other half of the challenge is determining the most appropriate thing to be doing,” Smith says.

Vaccination is just one strategy for prevention.  We also need to address management practices, making sure calves get mothered properly at birth, with timely and adequate colostrum intake.  “We need to be cautious about introducing new cattle (and new pathogens) and minimize opportunities for calves to share pathogens,” he says.

No two ranches have the exact same situation.  “People calving in sheds have different risks for calfhood diseases than people calving on dry hillsides or clean pastures.  This is why you need to talk with your veterinarian who knows your operation and understands your unique challenges and your own herd and management.”

Some diseases, like clostridia, are difficult to address with management, so vaccination becomes an important tool for protection.   “Clostridial vaccines are very effective, and good insurance,” Smith says.

For calves, the seven or eight way clostridial vaccines can be given at any age.  “The literature tells us that if there are maternal antibodies present these might not work, but field experience shows that those vaccines definitely have efficacy.  This is especially true if you are looking at C. perfringens in young calves, or blackleg,” he says.

“You can give these vaccines and usually not have to worry about problems with maternal antibody interference,” says Chase.  “Part of the reason is because with Clostridia we are vaccinating against an exotoxin.  This is a simpler antigen, easier for the immune system to see and attack, compared with some of the viruses (and all the processes that must happen to protect against those).”  If a producer is having problems with enterotoxemia, for instance, calves can be vaccinated at a very young age, even if the cows were vaccinated during pregnancy (to stimulate high levels of maternal antibodies in colostrum).

With most bacterial vaccines, it doesn’t do much good to vaccinate calves before three weeks of age, but the Clostridials are one exception to the rule.  “This is because of the toxins.  Toxoids are very effective vaccines,” Chase says.

Summer Pneumonia
“Some herds have trouble with summer pneumonia in young calves, and BRSV is a problem.  In these cases there are a couple approaches.  One is to use intranasal vaccine,” says Chase.

“The intranasal vaccines are good, and can be useful, depending on particular conditions on certain ranches.  If producers are not seeing summer pneumonia or rarely see BRSV in calves before weaning, there’s no reason to use intranasal vaccines; calves can probably mount immunity adequately with injectable vaccines.  But if a producer is trying to deal with summer pneumonia, getting an intranasal vaccine into those calves does seem to help,” he says.

“Intranasal vaccine has the ability to get around the maternal antibodies.  The other thing a producer can do is use an adjuvanted vaccine.  People often think that only an inactivated vaccine is adjuvanted, but we do have some adjuvanted modified-live vaccines.  We don’t yet know, however, how effective these vaccines are against BRSV in calves with maternal antibodies,” Chase says.

“If we have a summer pneumonia problem, BRSV is usually the culprit.  There’s no vaccine just for BRSV.  You have to use the combination product containing BRSV-IBR-BVD-PI3, even though at this age in calves the BRSV may be the only thing you are really worried about,” he says.

“The big thing is trying to match up (as much as possible) your vaccination program with the issues you’ve had to deal with.  A person may or may not need to vaccinate against bacterial pneumonia.”  Accurate diagnosis of illness is always important, to know what diseases should be included in a vaccination program.

“Sometimes summer pneumonia could be due to Mannheimia hemolytica or Pasteurella multicida.  Producers might use either the live or inactivated vaccine.  Some research indicates that even with inactivated vaccines there is some maternal interference, up to at least four to six weeks of age.  The response is quite variable, so we have to consider the issues.  At what age are calves having problems?  It often pays to wait until the calves are a little older, but if you are having a problem, you may need to address it quicker,” Chase says.

“We can see BVD antibodies coming up, even after 14 to 21 days, which is exciting, because we generally don’t see much response when we vaccinate with just one dose of inactivated vaccine (without following with a booster).  To use just one dose would be off-label, because we don’t have enough data to say you’d be safe with just a single dose,” says Chase.

“In most production schemes, it may be hard to give the calves a second dose.  In this instance you are stuck with using the things we know have that kind of label—that we can give a single dose and gain adequate immunity,” he says.

“At this point in time the intranasal vaccine gives the most likelihood of success and the least likelihood of failure, in that age group.  From two weeks up to three months, this makes the most sense, particularly if you are worried about BRSV.  The adjuvanted modified-live vaccine, where you give a single dose, also has some usefulness, but I haven’t seen enough data yet in young calves.  The intranasal vaccine, by contrast, has plenty of data to show that it works,” he says.

“The data clearly shows that it works well, in the face of maternal antibodies, when the researchers came back and challenged those calves 60 to 70 days later—as would be the case in calves that get summer pneumonia at one to two months of age.  If there’s a viral pathogen involved it’s usually BRSV,” says Chase.

It’s all about timing.  Work with your veterinarian to plan a strategic vaccination program that fits your situation and management.  “Evaluate herd history regarding disease (what you’ve dealt with in the past and at what age it occurred).  The idea that one size fits all does not work,” he says.

“Giving vaccinations at two to three  months of age has benefits.  Many calves will develop some response, though not all of them will be protected against respiratory pathogens at weaning time.”  Each calf may have a different status, regarding how he will be able to respond to that vaccine.

Maternal antibodies tend to interfere longer with some of the viral diseases, compared with bacterial infections that create toxins.  “The viruses are big proteins and have to be broken down and processed by the immune system in order to be fully recognized and attacked,” he says.

“I like the intranasal approach, but if the producer doesn’t really have a problem with BRSV in young calves, there’s no need to go that route,” Chase says.

The Clostridials will always stimulate good response in young calves, and a person should use intranasal vaccines (for viral diseases) only if it’s something you have to deal with—and then come back at branding time or later with a booster.  Timing is important, and if you are doing all the calves at once at branding, some of those calves may be two months old and some may be two weeks old, so their response will be vary.

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