Vaccinating too early, when calves still have maternal antibodies, may interfere with building their own immunities
Newborn calves gain temporary immunity against disease when they ingest colostrum because this first milk contains maternal antibodies.
After a few weeks or months this temporary protection begins to wane, 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 its system, these tend to interfere with building its own immunities.
Timing of vaccination, and with what, are thus the big questions.
Dr. Steve Hendrick of the Coaldale Veterinary Clinic in Coaldale, Alta., says ranchers should discuss a herd health program with their veterinarian but general guidelines may be helpful.
“Here in Western Canada, we advise most of our clients to use a BVD vaccine and it’s usually a five-way modified-live-virus vaccine. This, along with a clostridial vaccine, is probably most important for calves,” he says.
Additional vaccines are important for some.
“On ranches that have a lot of summer pneumonia in young calves, some veterinarians advocate a vaccine against mannheimia — what we used to call Pasteurella haemolytica — or histophilosis. I recommend this for herds that have problems with these bacterial infections.”
If calves are vaccinated at branding age for some of the pathogens that cause pneumonia, the shot they receive at weaning time acts as a booster. Though some producers don’t vaccinate at weaning, Hendrick said it’s important for replacement heifers or other calves that will be kept over winter.
As for the timing of vaccinations, “most of my clients vaccinate calves at about one to two months of age, when they are branded,” says Hendrick.
“Some herds experience disease in calves earlier than that and may need to work with their veterinarian to decide whether to vaccinate calves sooner, maybe using an intranasal product. Purebred herds that calve early and put pairs through a calving barn are more likely to use intranasal vaccines at birth.”
Vaccinating shortly after birth might also be better for late-season calving operations so animals don’t have to be brought in for treatment during summer’s heat.
“Vaccinating at birth isn’t ideal, but faced with whether to vaccinate at birth or not giving any vaccines, we choose to vaccinate calves at birth,” says Hendrick.
He has consulted drug company veterinarians about using clostridial vaccines early.
“Even though it says on the label to not give these before one month of age, we haven’t seen any problems with giving the vaccine to very young calves, and haven’t lost calves to blackleg or other common clostridial diseases, so I feel comfortable giving clostridial vaccination at birth.
“These cow herds have been vaccinated and boostered on a regular basis, so their calves may also be getting good protection (at least temporarily) from colostrum,” says Hendrick.
However, the best age for giving BVD and IBR vaccines remains debatable.
“From what I’ve seen in the literature, if you vaccinate calves that have high levels of maternal antibodies from colostrum, the thought has always been that those antibodies will mop up the antigen in the vaccine and the animal won’t develop a good response,” says Hendrick.
There are two types of immunity.
“One is cell-mediated — there are some immune cells that are non-specific and just clean up whatever foreign material they see. This is the first part of the immune system that develops and is important for most of the diseases a calf faces. There is probably an increase in this type of immunity with early vaccination, even though we might not see much increase in titers or antibody response.
“We feel that if these calves get exposed to the disease, they at least have good cell-mediated immunity from the early vaccination. This is very important for some of the viral infections. This is why I feel OK about switching some herds to vaccinating at a younger age. If calves are being branded later, I still recommend vaccinating at branding time,” he says.
An intranasal viral vaccine may work in some herds. It stimulates local immunity in the nasal passages, where the virus would normally enter.
“I think it depends on what the calves are exposed to. If the disease is bacterial rather than viral, a viral product won’t help,” Hendrick says.
Producers have to know the enemy before choosing the weapon, and consultation with a veterinarian is needed for that.