Bovine respiratory disease (BRD) has been around probably as long as cattle have, but it’s still a slippery devil to get our hands around whether we’re talking cows, calves, feedlot steers, beef or dairy. This special focus issue of Bovine Veterinarian is dedicated to taking a look at BRD in several of these scenarios.
We do know a lot about BRD, but our knowledge is greatly increasing with discoveries in immunology and genetics and how we can assist cattle in fighting the BRD complex. BRD is the most common disease among feedlot cattle in the United States, accounting for approximately 75% percent of feedlot morbidity and 50–70% of all feedlot deaths. BRD causes between $800 million to $900 million annually in economic losses from death, reduced feed efficiency and antimicrobial treatment costs.
I asked David Renter, DVM, PhD, Kansas State University, about the landscape of BRD research in general and the importance of continuing it. “BRD is still the leading cause of morbidity and mortality in feeder cattle, and it costs the industry hundreds of millions of dollars every year,” Renter says. “Further, there is simply a lot we don’t know about BRD — particularly, from the perspective of our research program and industry collaborators, we need more quantitative information on epidemiologic and economic factors that will allow producers and veterinarians to better manage the impacts of BRD within their production systems.”
Currently, Renter is analyzing data from feedlots to develop decision-making tools that will make it easier for producers to manage the health of their cattle. His research uses existing data to work toward several objectives, including developing a system to classify distributions of disease events within feedlot pens and generating estimates of what effect certain risk factors have on the multifaceted bovine respiratory disease complex. His team hopes to create decision-making tools that will let feedlot producers make more informed decisions about managing and treating their herds.
“It is important to fine-tune our efforts, because BRD is so complex and the cattle populations that we deal with in the industry are so diverse,” Renter says. “There is no ‘one size fits all’ with BRD management. Our resources including humans, facilities, product expenditures, etc. are not utilized efficiently unless we fine-tune these efforts.” Research has shown that “typical” ways of identifying BRD, through clinical signs and rectal temperature, are not very accurate. “Our sensitivity and specificity estimates indicate that nearly 40% of the BRD-treated cattle did not have BRD and a similar percentage of the cattle with BRD were missed,” says Renter, citing a 2009 JVDI study that he completed with Brad White, DVM, MS.
Renter says our ability to predict BRD risk on a set of cattle is highly variable — not bad on average — but most individual lots, particular for some types of cattle, will be misclassified. “These inaccuracies (and others) can have profound impacts on health and economic risk management.”
BRD research still explores traditional areas, but is also entering new frontiers, using new tools and ideas to address problems. “There continues to be a lot of research on mechanisms of specific bacterial or viral agents, interactions among agents, and responses and interactions among the host and agents,” notes Renter. “New ‘genomic’ tools recently have become central to many of these efforts.”