A well-managed Midwest cow-calf ranch has a problem with respiratory disease in its preweaned calves. They retain ownership, artificially inseminate and manage everything well according to Kansas State Veterinarian Brad White.
During a recent “Bovine Science with BCI” podcast, Kansas State University veterinarians Brad White and Bob Larson explore potential causes for bovine respiratory disease (BRD) in preweaned calves and how to mitigate the problem. White says discussing how to deal with preweaning BRD with producers can be frustrating because clear answers are not always possible.
Larson explains typical BRD preweaning symptoms for a spring calving herd will show up midsummer when the calves are about 4 months of age or a little older and still nursing on pasture.
“We could see 15% to 20% of the calves display symptoms,” Larson explains. “What we’re looking for is kind of typical, depressed, their heads down, maybe rapid breathing, those types of things. They’re not really being aggressive with their suckling or eating or anything.”
Larson reminds producers this fits the same description of respiratory disease in older calves. He says, likewise, some death loss can occur.
“Probably the most common what I see is up to 20% of the calves are affected, and from among those that we treat, you get just a few deaths,” he says.
Research Findings
Larson explains a recent K-State research project regarding BRD. Research surveys of more than 400 herds revealed several key insights. Several potential risk factors were identified that could contribute to preweaning respiratory disease:
- Artificial Insemination (AI) and Synchronization. Gathering cattle for AI can increase disease transmission and changing pasture dynamics and increasing close contact among calves.
- Management Practices. If cattle are managed using intensive grazing strategies or creep feeding these practices that alter normal grazing patterns and increase calf interaction and thus disease transmission.
- External Exposure. Grafting calves into a herd, grazing stocker cattle in the same pasture or any introduction of outside animals can be a potential risk factor.
- Immunological Factors. Declining maternal antibody protection at 3 to 5 months of age. Front-loaded calving seasons creating a cohort of calves vulnerable at the same time.
Larson stresses this is speculation because many herds do those types of practices and do not have a summer pneumonia problem.
“So, it’s not a smoking gun that if you do these practices, you’ll run into summer pneumonia,” he summarizes. “It’s just that we saw a little bit higher risk in those herds that did some of these, again, kind of changing the normal grazing distribution and pattern that calves interacted.”
Larson and White share several prevention and management strategies:
- Maintain strict biosecurity
- Isolate grafted or new calves
- Avoid commingling different cattle groups
- Ensure good nutrition and sanitation
- Consider vaccination protocols carefully
During the podcast, the researchers highlight the complexity of preweaning BRD, noting that no single factor guarantees prevention. Each herd requires a tailored approach and working closely with a veterinarian to understand specific risk factors.
The primary takeaway is that while preweaning BRD is frustrating and not entirely predictable, producers can mitigate risks through careful management, biosecurity and proactive health strategies. Good, foundational practices such as maintaining cow health, providing a sanitary environment and monitoring the herd remain the most critical components of prevention.
Producers experiencing recurring issues should reassess their management practices, vaccination protocols and herd dynamics to reduce the likelihood of preweaning respiratory disease outbreaks.
