Fresh Thinking For A Familiar Foe

Through collaborative research at VERO, scientists are uncovering new insights into one of the beef industry’s biggest health challenges.

Bovine respiratory disease (BRD) has challenged the beef industry for decades, costing producers billions of dollars annually while remaining one of the leading causes of illness, death, and antibiotic use in feedlot cattle.

Despite years of research and management efforts, BRD continues to frustrate producers and veterinarians alike — in part because the disease is far more complex than once believed — which is one reason why researchers at the Texas A&M Veterinary Education, Research, & Outreach (VERO) campus in Canyon have been leading efforts to better understand how BRD develops and progresses in cattle.

The initiative builds on years of BRD research conducted at VERO and supported by Texas A&M University, Texas A&M AgriLife Research, and the USDA. Since the program’s inception in 2019, VERO researchers have received more than $5.5M in USDA funding to investigate BRD and improve cattle health outcomes.

The research also brings together scientists from Texas A&M, West Texas A&M University, the University of Minnesota, Mississippi State University, industry partners, and cattle health experts for a series of projects that represent a growing shift in how researchers study BRD — moving from a narrow focus on individual pathogens toward a broader understanding of microbial communities, strain variation, and disease prediction.

“Historically, BRD research has often focused on individual pathogens or isolated aspects of disease,” said Dr. Paul Morley, professor and director of food animal research at VERO. “What makes this initiative different is that these projects are designed to work together to better understand the broader interactions occurring within the respiratory microbiome, the cattle host, and the production environment. That collaborative, systems-based approach is critical if we want to make meaningful progress against a disease as complex as BRD. Emphasizing collaborative teamwork is the best way to succeed.”

Looking Beyond Individual Pathogens
One of the VERO research group’s latest efforts led by Dr. Robert Valeris-Chacin is a USDA-funded initiative examining the role of Mycoplasma bovis and other microbial interactions in BRD, which received more than $763,000 in funding through the USDA’s National Institute of Food and Agriculture.

For years, Mycoplasma bovis has primarily been associated with chronic BRD cases — animals that fail treatment or develop prolonged illness. But researchers are beginning to question whether the bacterium actually plays a much earlier role in disease development than previously recognized.

That shift in thinking — viewing M. bovis primarily as a late-stage pathogen to investigating its potential role earlier in disease development — represents one example of how researchers are taking a broader, more systems-based approach to studying BRD.

“We have a reductionist understanding of the disease,” said Valeris-Chacin, assistant professor in the VMBS Department of Veterinary Pathobiology and VERO researcher. “We need to take advantage of recent technological developments to reassess what we think we know about the disease.”

Valeris-Chacin is leading the project’s primary research efforts focused on reevaluating the role of M. bovis in BRD. His earlier research found that cattle colonized with M. bovis shortly after arriving at feedlots were also more likely to later develop increased levels of Mannheimia haemolytica, another major BRD-associated pathogen.

In this project, Valeris-Chacin is expanding on that research by studying strain-level variation within M. bovis — rather than viewing the bacterium as a single uniform organism, researchers are examining how different variants may contribute differently to disease development.

“Each animal may carry a cloud of variants that are interacting with each other and with other bacteria,” Valeris-Chacin said.

By identifying which variants are most strongly associated with disease, researchers hope to better understand how BRD develops and progresses, while also laying the groundwork for more targeted diagnostics, vaccines, and treatment strategies.

The work could eventually influence how veterinarians approach BRD diagnostics, antimicrobial selection, vaccine development, and disease prediction. For example, researchers hope the findings could help identify cattle at greater risk of developing BRD earlier in the feedlot process, improve understanding of which M. bovis variants are most associated with disease, and support more informed decisions about treatment and prevention strategies. Valeris-Chacin said that the findings may also support more targeted antimicrobial stewardship strategies within feedlots.

A More Holistic View Of BRD
While Valeris-Chacin’s project focuses heavily on M. bovis interactions, another study led by VERO research scientist Dr. Lee Pinnell is taking a broader look at the respiratory microbiome. Building on earlier sequencing work conducted through VERO collaborations, the project reflects growing interest in applying advanced genomic tools to better understand complex livestock health challenges like BRD.

Rather than studying a single pathogen in isolation, Pinnell’s team is investigating how entire microbial communities within the respiratory tract may influence BRD risk and disease progression.

The project uses an advanced genomic sequencing approach called RNA-based shotgun metatranscriptomics, which allows researchers to examine not only which microbes are present within cattle but also what those microbes are actively doing at the time samples are collected.

“We’re trying to incorporate microbial interactions as opposed to looking at individual pathogens and how those relate to BRD,” Pinnell said. “That allows us to take a more holistic view of the respiratory microbiome and better understand how these microbial communities may influence disease progression.”

Researchers will collect samples from cattle at feedlot arrival, during BRD treatment, and following death during post-mortem examinations to compare microbial patterns between healthy and sick animals and between the upper and lower respiratory tract.

The goal is to identify microbial patterns or biomarkers associated with increased BRD risk — information that could eventually support more precise management decisions within feedlots.

“If we can identify patterns associated with animals that are more likely to get sick, that could eventually help inform management decisions in feedlots,” Pinnell said.

Collaboration Is Key
Researchers say the success of these projects depends on bringing together expertise from multiple disciplines to tackle a disease as complex as BRD.

The projects united scientists from Texas A&M, West Texas A&M, and industry partners, combining expertise in microbiology, genomics, cattle production, epidemiology, and feedlot management. No single discipline can fully explain or solve BRD, making collaboration essential for understanding biological, environmental, and management factors that influence disease risk and outcomes.

In addition to university researchers, the projects also involve industry collaborators and advisory board members with extensive expertise in cattle health and production systems. Their involvement helps ensure the research team remains focused on practical challenges facing the cattle industry and that discoveries can be translated into meaningful improvements in cattle health and management.

“To better understand BRD and mitigate its impact requires a more systematic approach that considers all the complicated factors of the disease,” said Dr. John Richeson, a professor of beef cattle feedlot management at West Texas A&M University. “I believe that the best BRD research leverages the talents of scientists across different disciplines, with different perspectives, and our collaborative projects are designed to do exactly that.”

The work also reflects VERO’s broader mission of conducting research that directly addresses major cattle health challenges facing producers, veterinarians, and the beef industry.

“The Texas Panhandle provides a unique opportunity for conducting this type of research because it is home to one of the largest concentrations of modern cattle production in the world,” Morley said. “This creates unparalleled opportunities to benefit the cattle industry by allowing us to study cattle health challenges under real-world conditions.

“VERO was established to leverage these opportunities and foster the cross-industry and cross-institutional partnerships needed to address complex challenges facing cattle production,” he said.

“These projects reflect that mission by bringing together researchers, veterinarians, producers, and industry partners and combining advanced genomic technologies with field-based research to improve our understanding of BRD, enhance our ability to predict disease risk, and, ultimately, support healthier cattle and more sustainable production.”