Narrowing Down Cattle Treatment Targets
Managing high-risk cattle gets a high-tech upgrade.
Cattle producers are adopting new technologies and tools to help reduce the number of antibiotic treatments administered to animals on arrival.
“Targeted antibiotic use has the potential to reduce costs and promote antimicrobial stewardship,” said Nathan Meyer, DVM, Ph.D., Boehringer Ingelheim. “Metaphylaxis is still a very effective tool that producers and veterinarians can utilize, but we can refine that tool.”
Metaphylaxis is an animal health management strategy where a group of animals is all administered antimicrobials to help prevent disease. When to implement metaphylaxis can be determined based on the group’s origin, travel history, or herd health status. Traditionally, producers visually identify signs of bovine respiratory disease (BRD). Today, more sophisticated software can help determine trigger points to administer individual treatments, metaphylaxis, or other interventions.
The models may help standardize treatment protocols – and even save producers’ money. A 2022 study by the Kansas Cattle Institute compared five classification models for BRD treatment decisions. One of the models showed a potential $5 per animal health cost advantage compared to the control. (1)
Dr. Meyer advises producers who want to target metaphylaxis treatments to consider the cattle before receiving occurs.
“It’s really about knowing your cattle,” he said. “Body weight is a determinant of metaphylaxis success. Lighter-weight animals are more at risk for BRD. The second metric is season. Fall-weaned cattle are at a higher risk for BRD. For these animals, metaphylaxis may be appropriate.”
It has long been known that commingled cattle are at greater risk for BRD. Plus, animals that have not been preconditioned before shipping have a higher health risk status, which makes it harder to fight disease successfully.
“These are the metrics producers have considered for years, but sophisticated models can weight different factors and hone in on trigger points for treatment,” Dr. Meyer explained.
The conditions just before – and during – travel also can affect disease susceptibility. In the past few years, many operations have been shipping lighter, nutritionally stressed cattle due to ongoing drought conditions across much of the West and Midwest.
“These cattle have undergone nutritional challenges and are not receiving macronutrients like energy and protein, or the micronutrients like vitamins and minerals, that they require,” Dr. Meyer said. “That puts them at greater risk of respiratory disease.”
Acute stressors during travel can also trigger the need for metaphylaxis. These situations include breakdowns during travel where cattle may be confined for longer than 24 hours. During these situations, he recommends assessing cattle in four areas:
The DART assessment allows on-the-ground visual assessments to help make the best animal health decision, which can be used whether an operation is inputting those observations into software tools or making a gut decision based on experience.
Working with a veterinarian to determine on-arrival protocols can give producers their best chance at a healthy (and profitable) return. When treatments are required, Dr. Meyer advises operations to understand the classes of drugs available.
“For instance, macrolides are used quite commonly, and there are some great advantages to that class of drugs,” he explains. “They are long-acting, the meat withdrawal time is short, and they are highly efficacious. Most macrolides have BRD control on the label. For metaphylaxis, it’s important to have ‘BRD control’ on the label. Not all antibiotics do.”
Next, producers should set realistic expectations for treatment success – and that may not include eliminating signs of disease. Reduced morbidity and mortality can still help save producers money and improve return on investment overall.
“We want to use these tools, antimicrobials, as long as possible,” Dr. Meyer said. “We have to use the ones available now judiciously because there’s not a new class of antibiotics that are coming to market for food animals, and we don’t anticipate any in the near future. Using them judiciously means making sure they are used in the right cattle that actually need it.”
1 Rojas HA, White BJ, Amrine DE, Larson RL. Predicting bovine respiratory disease risk in feedlot cattle in the first 45 days post arrival.
Pathogens. 2022; 11(4):442. https://doi.org/10.3390/pathogens11040442
2 Jobman E, Hagenmaier J, Meyer N, Harper LB, Taylor L, Lukasiewicz K, Thomson D, Lowe J, Terrell S. Cross-section observational study to assess antimicrobial resistance prevalence among bovine respiratory disease bacterial isolates from commercial U.S. feedlots. Antibiotics. 2023; 12(2):215. https://doi.org/10.3390/antibiotics12020215
Key Points (2):
- Bovine respiratory disease (BRD) is the leading cause of feedlot morbidity and mortality.
- BRD accounts for 70%–80% of total morbidity and 10%–50% of mortality in U.S. feedlots.
- Multiple viral agents can contribute to the development of BRD, including bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), parainfluenza-3 virus (PI3), and bovine herpes virus-1 (BHV-1).
- The combination of viruses, host stress, and environmental changes can enhance colonization and infection of bacterial species such as Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis.
- Due to the bacterial component of BRD, antibiotics are valuable tools for treatment and control.
- Veterinary diagnostic laboratories have reported general trends of decreasing antimicrobial susceptibility; however, it is unclear how the data compares to the general cattle population due to potential sampling bias.