Oregon’s cattle industry is a major part of the state’s agricultural economy. The Oregon Department of Agriculture ranks cattle and calves as Oregon’s No. 2 agricultural commodity, with a production value of about $791.5 million in 2024. That economic importance makes it critical to reduce health and productivity losses tied to growing threats such as wildfire smoke.

As wildfire seasons grow longer and more intense across the Western United States, livestock producers are facing a threat that can travel far beyond the fire line. Smoke can move hundreds of miles, exposing cattle well outside the burn area to fine particles that may affect health, welfare and performance.

Producers have reported concerns about pneumonia, reduced weight gain and reproductive problems after wildfire seasons. But there has been limited research showing how smoke affects cattle physiology, especially when animals do not appear seriously ill.

That left a practical question unanswered for producers and veterinarians: does short-term wildfire smoke exposure affect calves in ways that are real but easy to miss?

To help answer that question, researchers Juliana Ranches and Jenifer Cruickshank in Oregon State University’s College of Agricultural Sciences and OSU Extension Service studied 18 beef-on-dairy calves on a commercial dairy near Vale in 2022. The work tracked calf health before and after smoke from the Amelia Road fire affected local air quality for four consecutive days.

The calves did not develop obvious disease. They stayed within body normal temperature ranges and showed only mild respiratory signs, mainly nasal discharge.

But blood tests told a more important story. After smoke exposure, calves showed higher cortisol, a sign of acute stress. They also showed changes in inflammatory markers, immunoglobulins and cytokines, indicating that smoke exposure activated immune and inflammatory responses even without severe outward illness.

Those findings, published in the Journal of Animal Science, suggest wildfire smoke can act as a meaningful environmental stressor for cattle, including when effects remain subclinical and could be overlooked in day-to-day management.

Findings can guide livestock management

The study helps fill an important gap for livestock producers, veterinarians and researchers working to prepare agriculture for more frequent wildfire seasons.

By identifying measurable biological responses to short-term smoke exposure, the research provides an early foundation for better management during smoke events. It also points to practical strategies such as monitoring air quality, conducting timely health assessments and paying close attention to calves and other vulnerable animals when smoke moves into an area.

The findings are especially relevant in Oregon and across the West, where producers may face repeated smoke exposure even when their operations are far from active fires.

Ranches is an assistant professor and Extension beef specialist based at the Eastern Oregon Research and Extension Center in Burns. Cruickshank is an assistant professor and the Extension statewide dairy specialist. Both are in the Department of Animal and Rangeland Sciences.

Public value

OSU research is helping producers respond to a growing environmental challenge. By showing that wildfire smoke can affect calves before serious disease is visible, this work supports better management decisions, protects animal welfare and strengthens the resilience of Oregon’s cattle industry.

The study was partially supported by the Oregon Dairy Farmers Association, the U.S. Department of Agriculture’s National Institute of Food and Agriculture, Hatch project 1004721, and matching funds provided by the state of Oregon.