Vaccines Can Boost Immunity for Calves

by Kelly Driver

The newborn dairy calf is born into a dirty environment filled with bacteria, germs, viruses and a host of other microorganisms that can cause disease. This makes the first, critical delivery of antibodies from high quality colostrum so important to setting the calf on a healthy path because the cow’s placenta does not allow the transfer of essential antibodies in-utero. This systemic protection provided by colostrum in calves lasts from 2 to 12 weeks, depending on the quantity and quality of colostrum the calf received, the disease, and the level of exposure the calf is challenged with (Faries).

Additionally, producers have the opportunity to use vaccines to further bolster antibody levels in the calf. Let’s take a quick look at some things to keep in mind when developing a vaccination protocol with the herd veterinarian.

Types of Immunity

The purpose of vaccine usage is to protect the herd from harmful diseases, but to do this the animal’s immune system must develop memory. With each vaccination and booster, the goal is to provide the necessary protection by triggering the immune system to recognize the disease.

There are two basic types of immunity: passive and active. Passive immunity is immediate as it begins working as soon as the antibodies are absorbed, but this type of immunity is also quite short lived. Passive immunity typically offers about one week of protection, according to Dr. Rob Lynch, DVM in Cornell University’s Pro-Dairy Calf and Heifer Management course. He notes that passive immunity may be reactive, but the body doesn’t develop a long-term resistance and typically these products offer about one week of protection, according to Dr. Lynch (Lynch, 2020).

With active immunity, the body may have a delayed response, taking a few weeks to develop the immunity, but the results can last months or years. Modified live vaccines, bacterins and toxoids can all stimulate active immune responses.

Dr. Scott Nordstrum, DVM, associate technical director of ruminant life cycle management at Merck Animal Health, explains that calves have three basic sources for their immunity:

1. Maternal antibodies from colostrum provide passive immunity for disease protection. This is essential to protect a newborn for at least the first two to four months of life. As time passes, these maternal antibodies dissipate.
2. Innate immunity is the built-in response to disease challenges that nearly all healthy animals are born with.
3. Active immunity is protection from disease developed after exposure to disease or through vaccinations.(Source: Ryan)

Developing a Vaccination Protocol

Considering the possible diseases your calves and heifers could be exposed to is a great way to kick off a risk assessment with your herd veterinarian. It is also beneficial to consider where and when it will be easiest to safely handle the animals and get vaccinations completed on a regular basis. What additional labor may be required to complete the task?

After the thorough risk assessment is completed, work with your veterinarian to select vaccines. Giving consideration to safety, timing of vaccinations (and any necessary boosters), efficacy of the vaccine, and proper handling should all be included. Taking the time to read the vaccine information insert can provide many of the details about dosage, age and pregnancy status, proper storage, route and frequency of administration, and volumes of other valuable information.

Types of Vaccines

In general, there are three types of vaccines: Modified live, killed/inactivated, and a combination of both. The University of Minnesota Extension provides a nice explanation of each:

Modified live vaccine (MLV)

• MLVs are non-disease-causing versions of a virus or bacteria.
• The live virus or bacteria replicate in the animal similar to how the actual disease would, but does not cause the disease itself.
• The replication of the vaccine organism allows the immune system to develop a full response and create proactive immunity with only one dose of the vaccine.
• Many protocols recommend revaccination because not all animals respond to each vaccination.

Killed vaccines

• Killed vaccines do not contain a live virus or organism.
• Killed vaccines contain a dead organism or a specific piece of an organism that is critical to the function of the disease-causing virus or bacteria.
• The crucial difference between killed and modified vaccines is there is not replication with a killed product.
• For most vaccines, the lack of replication means the immune system does not develop the protective memory with just one dose and requires a booster.

Combination vaccines

• Some vaccines contain both modified live and killed products.
• These vaccines can protect against the live portions with one dose.
• The killed portion requires a booster to provide protection.

(Source: University of Minnesota Extension)

Intranasal Vaccines Often Used in Young Calves

One of the challenges encountered when vaccinating young calves is that they have received maternal antibodies that help protect them, but those same maternal antibodies can also neutralize antigens from an injectable vaccine, according to Dr. Nordstrum. “This is referred to as maternal antibody interference. We want to work with the colostrums – not against them. Peer-reviewed research suggests that maternal antibodies can inhibit the immune response to a vaccine in calves until their decline by 6 months of age” (Ryan).

Using an intranasal vaccine actually stimulates a different immune response in cattle. “One of the reasons we love intranasal vaccines is that they are demonstrated to be effective in the face of maternal antibodies because the antigen is introduced in close proximity to the mucosal surfaces,” Nordstrum explains. “They stimulate nonspecific immunity at the mucosal surfaces that helps provide protection against the respiratory pathogens found in the vaccine” (Ryan). This makes intranasal vaccines a good match for young calves and helpful to calf managers battling respiratory challenges.

Common vaccinations for calves and heifers

The central group of vaccines included in any vaccination protocol should be determined with the herd veterinarian during a risk assessment discussion. Often times the diseases are categorized by the body system they affect, such as respiratory or reproductive viruses and bacteria. Another group that may be included in a protocol address clostridial bacteria resulting in diseases like Blackleg, Redwater, and Tetanus.

Scours vaccines may be included in the protocol for pregnant animals prior to calving. Serum antibodies begin to move to the animal’s mammary gland 5-6 weeks prior to calving as part of colostrogenesis. The timely administration of scours vaccines can help provide very beneficial antibodies to the newborn calf through the resulting colostrum, as noted by Dr. Lynch in the Cornell Calf and Heifer Management course.

Handle with Care

Be certain to read labels and store vaccines properly. If vaccines need to be reconstituted, mix them gently. Shaking the bottle could release endotoxins. Several vaccines typically should be in refrigerated storage between 35-45^oF and anytime outside that range can begin to break down the vaccine. Be prepared to keep vaccines out of direct sunlight and in a cool container while using them. In warm weather conditions the challenge is to maintain the vaccine’s effectiveness.

Remember that vaccines are not absolute protection and offer a small piece in helping the host animal. They can aid in the prevention of clinical disease, by triggering the immune system to recognize the disease the animal is exposed to and respond, if the environment and pathogen load are not too overwhelming. A good vaccination program should go hand-in-hand with all the other measures taken to keep calves healthy – proper hygiene, excellent nutrition, and regular consultation with the herd veterinarian.

Kelly Driver, MBA has been involved in the New York dairy industry all her life. In addition to raising dairy calves and replacement heifers, she is the Eastern US & Canada Territory Manager for Calf-Tel. Feel free to contact her at kellydriver@hampelcorp.com with your calf questions or suggest a topic you would like addressed in a future blog.

References

• Armstrong, Joe, DVM. 2020. Cattle vaccine basics. University of Minnesota Extension. Retrieved at Cattle vaccine basics | UMN Extension
• Faries, Floron C., Jr. Cattle vaccines. Texas A&M Agrilife Extension. Retrieved at Cattle Vaccines – When should you vaccinate cattle? (tamu.edu)
• Leadley, Sam. Vaccinating calves in hot weather. Attica Vet Associates. Retrieved at VACCINATING CALVES IN HOT WEATHER (atticacows.com)
• Lynch, Robert A, DVM. November 2020. As presented in Cornell University Pro-Dairy Calf & Heifer Management Course.
• Ryan, Jennifer. (June 2020). The nose knows – internasal cattle vaccines. Veterinary Advantage. Retrieved at https://vet-advantage.com/vet_advantage/the-nose-knows-intranasal-cattle-vaccines/