Cows Produce Less Milk When They're Breathing Wildfire Smoke

A team at Oregon State University has started a three-year study into the effects of poor air quality from wildfires on dairy cows. In an area beset by increasingly severe and numerous wildfires, and where there are large dairy herds, identifying the impacts of wildfires on cows' milk production and welfare is crucial.

Juliana Ranches, working in eastern Oregon, said cows in that area are grazing outside in some of the most polluted air in the U.S. “We know there is a negative effect,” she told the Guardian, “but we cannot say for sure because there are no studies in a controlled environment looking into that.”

Preliminary Research

Research into the impact of particulate matter from smoke has been limited, but it is known to represent a significant health risk to the animals, especially when talking about long-term exposure.

New preliminary research from the University of Idaho has found that dairy cattle exposed to poor air quality and heat stress produced around 1.3 liters (1.4 quarts) less milk per day than the average. The study was only conducted on a small-scale and must be expanded in order to explore broader patterns. 

Ashly Anderson, who worked on this particular study, said, “Due to climate change and global conditions, we’re going to be seeing a lot more wildfires—and because of that there are going to be a lot more people and animals exposed to wildfires. Being able to tell what kind of effects there are and how we might be affected in the future is very important.”

Smoke Cows

In an attempt to collect more data, Ranches and her colleague Jenifer Cruickshank have begun their three-year study. As part of it, they have put 30 cows, which they refer to as “smoke cows”, out to pasture. 

Each time there is a wildfire event which results in an Air Quality Index measure of over 50, Ranches takes daily milk samples and blood tests, which are analyzed for stress markers. They also monitor and measure the cows' respiratory rates and body temperatures. 

“We’re getting a finer-grained picture of what these cows are experiencing, through poor air quality associated with wildfires—a better understanding of the physiological effects on them, like is it mild? Is it severe? Is there diversity among the response in the cows? With that information, we can start to look at the negative effects and minimize the damage,” she said.

Changes for Dairy Farmers

As summers in Oregon become hotter and drier, wildfires are on the rise, even in western parts of the state which have not historically seen them as frequently. This study and others into the impacts of smoke on dairy cows provide crucial information for dairy farmers, when it comes to both the welfare of their animals and their commercial yields. 

Even in coastal areas where wildfires are less frequent, rising temperatures and smoke from inland fires are becoming major concerns. Most coastal farm facilities are not equipped to provide shelter from severe smoke and prolonged heat. 

Dairy farmers in these regions may well have to consider finding solutions to changing weather patterns. For example, barns have to be redesigned to provide adequate cooling and ventilation, and such changes will come at a cost; but, of course, cow care and comfort are top priorities for all conscientious dairy farmers. And studies like this one will help inform best practice in our fast-changing world. 

Tami Kerr, executive director of the Oregon Dairy Farmers Association, is confident that farmers will be able to keep their livestock safe. Many have already installed fans and misters in their barns, and, as she stated, "Oregon is a national leader in milk quality, which reflects well on the care our farmers provide to their animals. Our producers are creative and will explore more options to keep their workforce, as well as their cows, as safe and comfortable as possible."