When Stress Tips the Scale: A Look at Calf Immunity and BRD Prevention
How stress, vaccination timing and product choice influence respiratory disease prevention in young calves.
Building immunity is not as simple as giving a vaccine
Preventing disease is always better than waiting for calves to show signs of illness. While proper animal husbandry and care are key to supporting calf health, vaccination remains central to managing bovine respiratory disease (BRD) and preventing permanent damage. To get the most out of any vaccination program, it’s important to understand how immunity develops.
“Just because we administer a vaccine doesn’t mean that equals 100% immunity,” said Matt Washburn, DVM, Boehringer Ingelheim.
Vaccination is a powerful disease prevention tool, but it does not override biology. The immune response depends on timing, energy and availability and the overall stress load on the calf at the time of administration.
“I like to think of stress as a seesaw effect,” explained Dr. Washburn. “You’ve got immunity on one side and layers of stress on the other. Every time we add a layer of stress, that scale is going to start to tip. Things like transport, handling, commingling, nutrition and hydration are all going to affect how that calf responds to vaccination.”
While some stressors — like weather — can’t be controlled, other events, including processing, transportation and commingling, can be planned for. When multiple stressors are stacked together, even well-designed vaccination protocols can underperform if immune demand exceeds the calf’s ability to respond.
“Stressors are likely to decrease the immune response to any challenge that might be going on,” said Curt Vlietstra, DVM, Boehringer Ingelheim. “Dairy calves are typically more accessible than beef calves. But, just because it’s convenient to vaccinate when you have your hands on a calf doesn’t mean it’s ideal timing for building immunity.”
To build immunity against a challenge like BRD, a calf’s immune system needs to have time to respond to a given vaccine. When possible, vaccination should receive scheduling far enough ahead of a stress event to allow immunity to develop.
“In an ideal world, we’re administering vaccines several weeks before a stressful event,” said Dr. Washburn. “From a stocker standpoint, that’s not a luxury always available. But it’s still important to understand that those few weeks are what’s going to offer the biggest bang for your buck out of a vaccine.”
While timing plays a critical role, it’s only one piece of an effective prevention strategy.
Understanding the vaccine you’re using is important
The foundational details for vaccination, like timing, are relevant to all calves, but building a protocol that’s unique to your business and herd starts with a conversation with your veterinarian.
“It’s important to ask questions like, What’s the risk of adding another vaccine or the risk of pulling one out? Do we have gaps in protection?” emphasized Dr. Vlietstra. “Having these important discussions with a herd veterinarian, or a professional services veterinarian like Dr. Washburn and me, sets up an understanding of what can realistically be expected from different vaccines in different groups of calves.”
Those conversations ultimately come down to immune capacity and product choice. Every additional antigen introduced into a high-risk calf increases immune system demand, which may already be managing stress, nutrition changes and pathogen exposure.
“Each vaccine you administer places its own demand on the immune system,” said Dr. Washburn. “When you’re talking about high-risk calves that already have a lot of stress on them, stacking a lot of vaccines on top of one another means they may not respond as well as you’d like.”
Dr. Vlietstra adds that immune demand isn’t just about the number of administrations.
“Sometimes, we look at one bottle and one syringe, but it’s important to think about what’s in that bottle,” he said. “Is it a three-way, a five-way, a seven-way? It’s not just how many shots you’re giving, it’s what’s in them.”
That’s where vaccine formulation becomes important. Differences in design — including the adjuvant type — affect immune stimulation, particularly in young calves that may still carry maternal antibodies.
“Historically, it was accepted as a fact that maternal antibodies would block an injectable vaccine,” said Dr. Vlietstra. “Now we know that the vaccine adjuvant MetaStim® works alongside the preexisting antibodies, not against them.”
For operations evaluating vaccine options, vaccine formulation can influence how effectively calves respond, especially when maternal antibodies are still present. Products formulated with the MetaStim® adjuvant, like PYRAMID® vaccines, are designed to stimulate a balanced, robust immune response in calves as young as 30 days of age.1
Vaccination results can vary based on management
The best prevention against BRD doesn’t begin at vaccination — it begins long before that. Early-life management decisions influence how resilient calves remain as stress comes and goes.
“For dairy calves, those first couple hours and days matter in terms of colostrum, bedding, hygiene and feed.” Noted Dr. Vlietstra. “It’s hard to get that time back if a mistake is made, or something is missed. Many of the dairy calves we see that are treated for pneumonia were previously caught and treated for diarrhea. Being able to watch those calves closely and adjust quickly gives you the best chance of having a healthy calf.
In stocker and feedlot systems, groups of calves will arrive with varying health backgrounds. That history plays a significant role in how well a vaccination program performs.
“Many feedlots or stockers tend to have one protocol, and give it no matter what kind of cattle.” Shared Dr. Washburn. “The history of those calves matters — preconditioning, travel history, weather, where they came from. The same vaccination protocol can perform very differently, depending on those factors.”
Even within a closed dairy, a protocol that has previously achieved great results may shift in response to disease risk or seasonality.
“There are so many variables that can’t be fully predicted,” added Dr. Vlietstra. “You can have the same protocol year-round, and it might work well in one season and struggle in another.”
Disease risk is dynamic, regardless of cattle type or age group. Because stress load, immune demand and pathogen exposure are constantly shifting, prevention programs can’t remain static.
Both Dr. Washburn and Dr. Vlietstra recommend regularly reevaluating prevention strategies to keep protocols aligned with real-world conditions. Your herd veterinarian can help evaluate calf history, stress load and vaccination timing to ensure respiratory disease prevention programs evolve with the realities calves face.
