Wildfire Smoke Triggers Significant Drops in Dairy Milk Yield, University of Idaho Research Shows
When wildfire smoke blankets the Pacific Northwest, most humans reach for N95 masks or retreat indoors. Dairy cattle, however, have no such escape route. New research from the University of Idaho reveals that prolonged exposure to heavy wildfire smoke cuts milk production by up to 10% per cow, with losses persisting for at least a week after the skies clear.
Amy Skibiel, an associate professor in the Department of Animal, Veterinary and Food Sciences at the University of Idaho, led the investigation into how fine particulate matter impacts herd productivity. As uidaho.edu reported, the study tracks how environmental stressors alter metabolic and lactation functions in livestock.
Tracking Unpredictable Smoke Events on Local Dairy Farms
Studying wildfire impacts requires managing two distinct layers of unpredictability: volatile weather patterns and livestock behavior. Skibiel’s team monitors real-time air quality data from a local monitoring station to measure concentrations of PM2.5—microscopic solid and liquid particles less than 2.5 micrometers in diameter.
Because PM2.5 comprises roughly 90% of wildfire smoke and is heavily documented for causing adverse respiratory and systemic effects in humans, researchers focused heavily on these fine particles. Before wildfire season begins, field teams visit regional farms to establish baseline health metrics. They record vital signs, draw blood samples to analyze metabolic and immune markers, and track milk composition.
When regional monitoring stations record sharp spikes in PM2.5 due to wildfire activity, the research teams return to the farms to repeat every measurement. Follow-up visits continue for up to a month after smoke events dissipate, capturing a complete physiological timeline.
Measuring the Production Drop in Dairy Herds
During the 2020 wildfire season, a sustained week-long period of high PM2.5 concentration provided clear observational data. Milk yields dropped consistently throughout the active smoke event and remained suppressed for at least seven days afterward.
With that wildfire event, we saw decreases in milk production during the entire time that event was occurring, and then for at least seven days after the smoke dissipated. That decrease in milk production was up to nine pounds per cow per day, depending on what the particular PM concentration was that day. That’s roughly 10% of what these cows are producing in a day. — Amy Skibiel, Associate Professor, University of Idaho
The data demonstrated a direct mathematical correlation: milk yields dropped by roughly three pounds per cow daily for every 100 microgram per cubic meter increase in PM2.5.
