BRD frequency and mitigation
Bovine respiratory disease (BRD) is a multifactorial disease with a persistent frequency in the commercial feedyard industry and probably also in stocker and backgrounding operations. For all feedlot cattle placed, the frequency of BRD was 14.4% in 1999 and 16.2% in 2011. Feedlot cattle death loss (1.2% total) due to BRD was 57% from 1994 to 1999, and 55% of 3.06% non-predator death loss in 2015. The review of BRD in this article pertains to those BRD cases that emerge within 50 days after arrival, with emphasis on BRD cases in weaned calves.
Many useful pharmaceutical products have been developed to treat BRD; however, effective implementation of a preventive strategy has been elusive. A further complication is the absence of an experimental model that replicates the most common clinical symptoms. A 2010 study led by Jared Taylor at Oklahoma State University concluded that the practices that reduce BRD frequency and severity are:
- Weaning 21 days or more prior to shipment
- Metaphylactic administration of injectable antimicrobial products
- Avoiding addition of new cattle to an acclimated group
Derrell Peel at Oklahoma State University noted in a 2020 article that misalignment of costs and benefits across our industry segments results in suboptimal investment in BRD control. He recommended that a production system-wide focus on lifetime animal health would be needed to make progress in reducing BRD incidence.
Challenge posed by E. coli O157 and response
The U.S. beef industry faced a similar industry-wide challenge in 1993 when undercooked ground beef resulted in human hospitalizations and deaths. The response of the post-harvest beef industry was to develop a strategy for impeding the transfer of E. coli O157 from incoming cattle onto and into fresh beef using a strategy that became known as Hazard Analysis Critical Control Points (HACCP). Meat product safety was declared by consensus to be a non-competitive space; therefore, information generation and exchange among industry participants occurred via the Beef Industry Food Safety Council. The HACCP strategy, implemented on an individual plant basis, has been effective as indicated by progressively decreased attribution of E. coli O157 cases to beef.
Bringing BRD home
A large portion of feeder cattle (38.2%) pass through an auction barn on their way to feedlots. In addition, 30.7% pass through backgrounding or stocker operations, which implies likely passage through an auction barn (although a portion of this percentage includes video auctions). Moreover, 32.7% of feeder cattle placements involve cattle that are commingled from different sources in the first 45 days of feeding.
When the gavel slams, the buyer also has purchased the virome, microbiome and recently accumulated stress of these calves. Peel lamented the lack of coordination in animal health management across production segments, especially pointing out that the health of stocker and feedlot cattle is largely determined at the cow-calf level. Improving that coordination holds obvious benefits, but the reality is that achieving this objective is not likely in the foreseeable future since there are so many individual cow herds – namely, some 622,000 U.S. cow-calf herds.
The aim of this article is to pose the question whether all avenues for BRD intervention have been explored for background and feedyard operations and also for auction barns. Moreover, is there no option for an auction barn other than to pass the BRD risk to the buyer? Could a comprehensive approach to reduction of BRD frequency be effective, as was the case when E. coli O157 contamination of fresh beef was attacked via HACCP procedures?
Metaphylactic administration of antimicrobials has been and is the most effective strategy for BRD mitigation at the feedyard level in view of current risk assessment methods, diagnostic technology, economic signals and labor availability. However, given emerging social and microbiological responses to these antimicrobials, a comprehensive approach to guide antimicrobial use will be needed. Antimicrobial resistance to the commonly used antibiotics occurs in the BRD pathogenic bacteria, and its prevalence is increasing.
Symptoms of BRD include fever, coughing, navel discharge and lack of appetite. Image courtesy of Dan Schaefer.
Development of a HACCP plan
A comprehensive approach could be the development of a HACCP plan, with the (probably unattainable) aim of BRD prevention in newly received feeder cattle. Seven basic principles are employed in the development of HACCP plans that target the stated goal. These principles include hazard analysis, critical control point identification, establishing critical limits, monitoring procedures, corrective actions, verification procedures and recordkeeping and documentation. While there would be some commonality among individual plans of auction barns, backgrounding yards and feedyards, there would be many additional critical control points and practices unique to each individual plan. Suggesting use of the HACCP approach is not novel; multiple industry researchers have advocated in the last decade for veterinarians to use client operational data for animal health management because analysis and conclusions from those data could be directly applicable. Moreover, the Beef Quality Assurance program uses a HACCP-like approach to ensure beef safety and quality benchmarks.
HACCP seems like a reasonable approach, but which are the critical control points? Taylor’s 2010 study critically reviewed the literature and discerned three consistent factors that predisposed cattle to BRD:
- Calves shortly after transport and arrival
- Purchase via an auction barn
- Commingling of cattle from different sources
It was also noted that lighter-weight calves seemed to be more susceptible to BRD than heavier cattle, and transfer of colostral immunity influenced BRD susceptibility. Cattle persistently infected with bovine viral diarrhea virus increased BRD frequency, but this factor was without major impact. Other stress factors such as weather, weight on arrival, sex, castration, dehorning and heterosis impacted BRD development and prevention, but the role of any single factor was difficult to define due to the complexity of BRD.
A 2023 study in Australia reviewed BRD preventative practices by segregating them into animal preparation practices and feedlot management practices. In the scope of this article, feedlot management practices and additional novel practices would be included in the HACCP plan.
When considering the design of a HACCP plan, it seems prudent to recognize that pathogen transmission could occur within a pen or between pens. French investigators in 2012 housed bulls in pens that allowed nose-to-nose contact, and they used methods that allowed them to distinguish among strains of Mycoplasma bovis collected from the lower respiratory tract. They concluded that transmission of M. bovis strains within pens of cattle occurs, with the source of the M. bovis strain spreading among cattle being either newly acquired cattle or cattle housed in neighboring pens. Intrapen pathogen transmission is impractical to intercept; however, interpen transmission could be prevented. For example, the sharing of a water trough between pens has been suggested as a significant risk factor.
A subsequent article will further explore this topic.
References omitted but are available upon request by sending an email to the editor.
