by: Heather Smith Thomas
Newborn calves gain temporary (passive) immunity from disease when they ingest colostrum from the dam—since this “first milk” contains maternal antibodies. After a few weeks or months this temporary protection begins to wane, however, and calves must build their own immunities. Vaccinating calves at the proper time can help protect them until weaning age. Vaccinating them too soon, however, 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.
Dr. Mark Alley, Clinical Assistant Professor, North Carolina State University College of Veterinary Medicine, says that since we don't know how much maternal immunity each calf gets, it will wane at different times for each animal. “It's also going to be different with each of the bacteria or viruses we are talking about. So vaccine recommendations will be very dependent on what the potential issues are on each farm.” Each producer must plan a strategy to fit his/her own situation.
“You don't always know what the exposure is, for the cattle. In our part of the country, fenceline contact is an issue, and in the West many cattle are co-mingled on rangeland. There may also be animals coming in or out, or purchased animals coming into the herd. The history (of problems) in that set of cattle is also important to know. All of these things play a role in developing a program specific for each farm,” he says.
“One of the things that researchers have discovered is that there are a few viruses—specifically IBR, BRSV and PI3—that may not be blocked by maternal antibodies as much as we earlier thought. As a result, we may be able to vaccinate calves at an early age and still get an immune response. However, pathogens like BVD, Pasteurella, Mannheimia, etc. may actually be blocked by maternal antibodies. Therefore vaccinating with these antigens needs to be discussed with your veterinarian before using them in young calves,” says Alley. As long as the passive transfer is still strong, the calf may not build his own immunity to these in response to vaccination.
“These calves may not respond effectively. Due to the cost of trying to figure this out, and how much variability there might be among calves, the issue of calfhood vaccination is a big challenge—as to whether or not we should be vaccinating calves at branding time or any other time prior to weaning,” he says.
“Most of the time, I base this decision on the history of the farm. In our part of the country producers usually don't do very many vaccinations prior to weaning. Often they won't be getting the cattle in from pasture before that. They aren't going to be processing them for any other reason (since in the East they don't have to brand them),” explains Alley.
There are some vaccines that have been shown to provide some immunity at an early age, and most of that research has been done by the individual companies that make the vaccines. “Some vaccines will provide some immunity for these calves, even in the presence of maternal antibodies. The problem is that if we vaccinate a calf that has maternal antibodies present, and come back later to pull blood to see if that calf responded to the vaccination, if we only look at antibody levels it may look like the calf did not develop an antibody response. But then when the immune protection starts to wane (at 4 to 6 months, depending on which pathogen we are talking about), if we vaccinate that calf again, with a similar product, we get an immune response very similar to an animal that received a booster,” he says. There is some recognition and response to the vaccine, even though it didn't appear that the immune system responded, the first time.
“Right now we are trying to encourage people to do more vaccinating early—like they do in the West at the time of branding. For our producers, we label this as the time to castrate the calves, and give vaccinations at that time,” he says. Some producers may also be giving the cows some pre-breeding vaccinations, and this make a good time to vaccinate the calves as well. If the producer is handling the cattle for some reason, this creates an opportunity to do the calves.
“Vaccination at some point during the first three months of life can be extremely beneficial and can actually reduce the stress at weaning time. The calves will already be accustomed to going through the facilities, and maybe we'll get a better response to the weaning-time vaccine,” says Alley. The earlier vaccination can set them up, and the weaning vaccination acts like a booster.
The primary goal is to reduce stress at weaning. “We know that the day of separation from the cow is one of the most stressful times in the calf's life. If we can do some things to reduce this, it will be helpful. I prefer to do fewer procedures on the day of weaning,” he says.
Alley doesn't see very much respiratory disease in calves pre-weaning, in his region. “Usually if we have any respiratory disease before weaning, there's a history of poor nutrition, or introduction of new animals into those herds,” he says.
“Many producers don't give the clostridial vaccines to calves until they get to be at least 3 to 4 months of age, and then we try to make sure that they get a booster at some point after that, as well. If a herd has a history of problems in young calves, or a history of tetanus (when banding calves), we recommend clostridial vaccines be given soon after birth,” explains Alley.
“We try to convince producers about the benefit of doing these vaccinations while the calves are still on the cow. The calves are not as stressed, and build better immunity. If producers don't do the early vaccinations, we recommend they vaccinate the calves two to four weeks prior to the estimated date of weaning. The calves should receive the viral and clostridial vaccines at that point. This may or may not include pasteurella or pinkeye, depending on what the risk factors are for that herd or farm. Then the calves get boosters at the day of weaning,” he says.
“We have some producers who can't separate the cows and calves twice. In this situation they try to get the first dose of vaccine into the calves on the day of weaning and then come back with a booster afterward. It's extremely farm dependent on how successful this particular system works,” says Alley. It may partly depend on how stressful their weaning program is—whether fenceline weaning or abrupt separation from the cow. Anything a person can do to reduce stress will be helpful.
“Nutritional factors are also important. Do they do a good job of nutrition at weaning? Can we get calves to eat as much feed the day after weaning as they did the day before weaning? Is it a palatable diet? Is there enough bunk space available for all the calves? What is the ambient temperature? In our area, one of the biggest stressors is actually heat. The time of year the weaning is done can make a big difference. About 50 percent of our herds are fall calving and 50 percent are spring calving. Whenever we're doing fall weaning, especially on animals that are grazing fescue pastures, heat stress can be a big issue—particularly if they don't have shade or water available.” This can be just as stressful as weaning calves in cold temperatures in a blizzard.
Each producer must figure out the best vaccination program for his/her own situation. “It would be nice if we just had a cook-book recipe to follow, and a vaccination program that everyone could use, but it doesn't work that way. Some of the basics are the same, but the timing, and which products to use are all going to be very much farm dependent,” explains Alley.
It pays to discuss these things with your veterinarian and try to fine-tune it to your own situation. The veterinarian may have some suggestions as to which products, and when, might work best in your herd. “The veterinarian may also have some idea about the problems that are occurring within your area, that you may not be aware of. When I do producer meetings I tell them the goal is not just sticking the vaccine into the calf. The goal is to administer the vaccine and actually get an immune response. The focus should be on immunizing the calf. To achieve this, the whole system—animal and farm—needs to be understood,” he says.
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