Episode 12.4: Wildfire smoke takes a toll on dairy cows

Amy: 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.

Danae: Hi, everyone. Welcome to The Vandal Theory, a podcast about science and research at University of Idaho. I'm your host for the day. I'm Danae Lenz, external communications coordinator at U of I. And I am joined by Leigh. Hi, Leigh.

Leigh: Hi, Danae. I'm Leigh Cooper, University of Idaho science writer and editor, and I'm excited to be a part of the podcast today.

Danae: Today, we're talking about dairy cows and wildfire smoke. To kick us off, have you ever had an adverse reaction to wildfire smoke?

Leigh: I mean, nothing so extreme that, like, I needed to go to QuickCare or the hospital or anything like that, but I do hike and bike during the summer and I've definitely pushed the envelope in terms of when I've gone out when there's been wildfire smoke thinking that, "Oh, I think it's fine." And then like halfway through the hike, I'm sitting there going, "This is harder than usual." And then having my lungs burn for like the next 24 hours. So yes but I know it can be worse for others.

Danae: I also have never had a crazy reaction, and in fact, I'm kind of stubborn. I really like sitting out on my patio. So even if it's a smoky day, like I don't know, I'm kind of sitting out there and the entire time I'm like, "What am I doing to my lungs?"

Leigh: I guess we're about to find out.

Danae: We are. Well, we're at least about to find out how wildfire smoke affects cows. Spoiler alert, it does do something. Today we're talking with Amy Skibiel. She's an associate professor in U of I's Department of Animal Veterinary and Food Sciences. She studies lactation physiology and how environmental stressors affect dairy cows and their calves. We'll hear what happens when cows are exposed to wildfire smoke, whether the effects continue after the air clears, and what researchers are learning about protecting milk production and animal health. Are you ready to get started?

Leigh: Let's mooove.

Danae: Hi, Amy. Welcome to The Vandal Theory.

Amy: Thank you for having me.

Danae: To get us started, can you just tell us a little bit about who you are and what you do?

Amy: Absolutely. So my name is Amy Skibiel I am an associate professor of lactation physiology in the Department of Animal, Veterinary and Food Sciences at the University of Idaho. And I consider myself to be a lactation and environmental physiologist. So my research addresses animal responses and adaptation to environmental stressors, particularly poor air quality from wildfires and also heat stress. And my overall goal in the research that we do in my lab is to leverage the information we gain from our work to benefit the agricultural industry, ideally through improvements in herd health and productivity in light of changing environmental conditions.

Danae: How did you get into that area of study?

Amy: That's a great question. So when I was a postdoctoral fellow at the University of Florida, I was studying heat stress and how heat stress impacts milk production from a mechanistic perspective. So heat stress is obviously a huge problem. It's a big problem in the dairy industry because when cows are lactating, they're producing more heat and that makes them more susceptible to higher ambient temperatures. And so I was looking at processes that were happening within the mammary gland, specifically cellular processes and, and changes that were happening at the cellular and tissue level to try to understand how heat stress was reducing milk production in an effort to identify pathways that we could potentially manipulate to help cows, to give them a boost, and try to improve milk production in the summers, especially when temperatures are really high in Florida. So that was kind of my entrance into a lot of the environmental work that I've continued doing here in Idaho.

But I grew up in Pennsylvania and wildfires were just not something that I was exposed to when I was growing up and really wasn't something that I was exposed to until I moved out west in 2018 for this position. So shortly after I started my position here at the University of Idaho, I participated in a conference in Boise and I drove down to Boise with one of my colleagues in the department. And you know, we just got to talking about the environment and the weather conditions in Idaho, and I had heard from many other colleagues and from students about how bad the wildfire smoke can be here in the summers, but as of yet, I had not experienced that myself. Through that conversation, began to talk about and began to question what effects there might be on cattle because unlike many humans, cattle don't have the opportunity to escape episodes of poor air quality, especially in the Pacific Northwest where wildfires are prevalent in the summers.

Here, our cattle are typically housed on dry lots, which means that they are exposed to whatever the prevailing environmental conditions are. There are typically windbreaks and there are shade structures, but in terms of the air quality, in terms of temperature, the animals are exposed to that. We just started questioning and wondering what might be going on with the cows, if they might show similar responses to humans, perhaps more robust responses given the fact that they, they can't escape those episodes. And due to some aspects that we know are different between the anatomy of a lung in a cow versus that of a human. And so I said, "Well, why don't we do a study? No, nobody's doing this. I certainly have the expertise and the capacity to do this. I've been working on environmental stressors and understanding animal responses to environmental stressors for many years, so let's do it." And so that summer we started our first research project to look at the effects of wildfire smoke on cattle just to see if there, if there was any effect on, on health and production.

Well, that was the summer of 2019 and we coincidentally did not have any wildfire events that summer, which is a good thing. I want to say that is, that is a very good thing. But that also gave us an opportunity to prepare a little bit better, I think, for, for subsequent projects. And so when the 2020 wildfire season rolled around, we were poised and ready to go. So that is my very long-winded answer to your question about how we got on the track of studying wildfire smoke in relation to cattle health in the first place.

Danae: Okay. And what does it look like in practice? And to your point that you just said the, smoke isn't always cooperating with what you want to do. So how do you study something unpredictable like that?

Amy: Yes, I think that's a great question because you not only have the unpredictable nature of wildfire events, but also the unpredictable nature of working with animals that also don't always cooperate with what you're trying to do. So in practice, use a state monitoring station that's located in Moscow along with AirNow, which is a governmental website, to track changes in particulate matter along with wildfire activity. So particulate matter is just solid and liquid particles that are suspended in air, and they're a main component of wildfire smoke. We are particularly interested in fine particulate matter, that is PM2.5, and it's called that because, so particulate matter is categorized based on size. So PM2.5 consists of particles that are less than two and a half micrometers in diameter. So we're talking about microscopic particles here. We are particularly interested in PM2.5 because it comprises about 90% of the particulate matter in smoke, so it's a huge component of smoke.

And there is a robust literature in human epidemiology that PM2.5 is responsible for many of the health effects that have been reported in humans. So our focus has been on PM2.5. We have a local monitoring station that tracks and records PM2.5 and so by tracking changes in those concentrations in the air, along with wildfire events, we know when the environment is changing, when the air quality is changing, and that gives us notification that we need to take action and collect samples on farm. So early in the summer, we try to collect baseline data from cows and calves prior to any wildfire events. So what that looks like is we will go out to the farm that we're working on. We will record vital signs like body temperature and respiration rates. Those signs give us a snapshot of that animal's basic health status.

We also take blood samples and we do that to measure blood metabolites that give us an indication of what that animal's metabolism looks like. And we also do an analysis for various immune markers so we have an idea of the animal's immune status as well. In cows, we record milk yield and we take samples to assess milk composition so that we have some production data as well. In calves, we also do health scoring and that uses a standardized chart that was developed out of the University of Wisconsin-Madison. And that chart has a scoring system of observable signs of illness. So we can use that scoring as a composite of that animal's health status. And then in calves, we also have been doing lung ultrasound scoring. So we just take an ultrasound, we look at every lobe of the lung, and by doing that, we can determine if there are areas of consolidation or lesions in the lung.

So lung consolidation just means that there are areas of the lungs that should be filled with air that are now instead filled with fluid, with pus, with cells, and typically that is caused by pneumonia. So it gives us an idea of potentially subclinical or clinical pneumonia or injury to the lungs. So we try to collect all of those baseline data, as I mentioned, before we see any wildfire events. And then we basically just monitor those data that are coming out of the Idaho Department of Environmental Quality from their monitoring station in Moscow and from AirNow. And when we have spikes in PM2.5 that are attributed to wildfire events, then we go back out to the farm and we collect all of those data and all of those measurements again from those animals. Then we typically do that throughout the wildfire season with all the wildfire smoke events that we have.

And then typically a week up to a month following wildfire season after the smoke dissipates, we'll go back out and collect a final sample so that we then have data from before the wildfire events, during the wildfire events, and then a follow-up post-wildfire season.

Danae: Okay. And out of curiosity, how many animals are we talking about?

Amy: So we have been working with typically between 20 and 30 animals at a time. So 20 to 30 calves, 20 to 30 cows. And we don't always have cow and calf trials going on at the same time, but sometimes we do.

Danae: So now let's talk results. What have you found out?

Amy: I love talking about the results because they're very interesting. So in the 2020 wildfire season, we had one long one-week period where PM2.5 levels were pretty high. So in that particular summer, 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. I say at least because we only looked at one week following exposure, so we don't yet know how long those production impacts last after wildfire events. That decrease in milk production was up to nine pounds per cow per day, depending on what the particular PM concentration was that day. In other words, there was a decrease of roughly three pounds of milk per day for every 100 microgram per cubic meter increase in PM2.5. So it was a drop of up to nine pounds per cow per day at milk production.

That's roughly 10% of what these cows are producing in a day, just to put that into context. We also found that when cows are exposed to wildfire smoke, there's a decrease in tidal volume, which again is a measure of lung function. We find that there are changes in inflammatory markers both within the lungs and also systemically. We have also discovered changes in metabolism during wildfire smoke events based on the blood metabolites that I mentioned earlier. So those results seem to indicate that cows have a change in how they are using and metabolizing fats and proteins in the body during wildfire smoke events. We have also observed increases in respiratory rate in cows during wildfire season. That's a problem because when there's air pollution and cows are breathing faster, that could mean that they're potentially inhaling more pollutants into the body.

And then lastly, we also find changes in immune cell populations which indicate that the animals are mounting an immune response to those inhaled pollutants. In calves, we have also seen signs of illness, especially respiratory irritation like coughing, more discharge coming from the eyes. We have found increases in lung consolidation during smoke relative to before smoke. We have also seen that in a more controlled experiment where we had a control group that was not exposed to wildfire smoke and a group of calves that was exposed to wildfire smoke. So in that study, we also found that there was more lung consolidation in the calves that were exposed to wildfire smoke compared to the calves that were not exposed. Similar to cows, we see increases in respiratory rate and immune cell population changes in the lungs and throughout the body. So in both cows and calves, there seem to be effects on health and also on performance.

Danae: What are producers supposed to do with this information, right? Like obviously their animals are being harmed in some capacity and no one wants that for a variety of reasons. So what are they supposed to do?

Amy: I've definitely heard the response, "Well, there's nothing we can do about it, so what's the point of studying it?" My counter argument to that is, "Well, if we don't know it's a problem, then how are we supposed to come up with solutions to the problem?" Right now, the guidelines that we have in place in terms of on the ground things that producers can do are to monitor animals during and after wildfires because there, as I just demonstrated, there are effects on animals during and then also for a period of time after smoke exposure. So paying special attention to young animals that might be more vulnerable to inhaled pollutants and also to sick animals that are already, you know, battling an illness that might be more vulnerable to smoke. And then seeking prompt veterinary consultation for treating any animals that producers suspect of having immediate burns or that are suspected of having smoke inhalation injury, which could be evident through some of the things that I mentioned earlier on that we're measuring, like observable signs of illness from droopy ears to nasal or eye discharge, changes in respiratory patterns, difficulty breathing, lethargy, not eating.

Those all would be signs that should prompt veterinary care for those animals. And then beyond that, minimizing additional stressors that an animal might be faced with during the time that they're already trying to battle and respond and react to inhaled pollutants. So that would mean potentially limiting exercise, try to hold off on regrouping animals, which can be a stressful event for social animals, postponing transportation. So sometimes animals are transported short or long distances. There's a lot of literature showing that that is a stressful event for animals. So all of those things we can do management-wise will help those animals be able to appropriately respond to and combat any inhalation of those particulates from wildfire smoke. And then I would say following a wildfire smoke event, it's important to keep good records on animals that are sick, any treatments that were provided, production level data that might indicate losses.

These are especially important when reporting for insurance purposes or for governmental or recovery programs. So those are the strategies and the tools and guidelines that we have currently, but now that we know that wildfire smoke is a problem to cows in terms of their health and production, and we're starting to learn about some of the underlying mechanisms that are contributing to those effects, we can start to devise more targeted approaches to mitigate that stress and to help improve herd health during and after those events.

Danae: What questions are you hoping to answer next?

Amy: I mean, I think the biggest one, as I just alluded to, what are the additional tools and rubrics that we can provide for producers so that they can better manage their herds during those events to have the best possible outcomes for their herds? And also what can they do during that event to best protect their animals? So we are starting to do some of that research now. This summer we're testing a method to try to reduce the amount of particulates that animals are exposed to during wildfire events, and that's something that we will continue doing into the near future. I think another question we have is what are the longer term risks? As I mentioned, we've really just been looking out, you know, a week to a month or so after wildfire season. So when animals are ill, when production drops during wildfire season, how long do those effects last?

I think that's a very important question. So those are two that we're really focused on right now. And I should mention that we have done a study where we have looked at calves up through 12 months of age. So in that study, calves were exposed to wildfire smoke early in life around two weeks of age and then again at nine weeks of age, and we follow them out to 12 months of age. And we do see lingering effects for at least a couple of months after smoke exposure in certain areas. And then they seem to recover, which I think is a really good sign and that's very promising for producers. Even in terms of lung consolidation, we see lung consolidation occurring for multiple weeks after exposure, but when we're looking out to, you know, two, three, four months after exposure, those animals have recovered.

Danae: So we're almost done here, but I just want to ask, what do you most want people to take away from the work that you do?

Amy: I think the most important point is that this is a real problem and it's a real problem that is affecting producers, not only in the Pacific Northwest, where we often have wildfires during the summer, but it's becoming increasingly problematic throughout the country as that smoke blows across the Midwest into the east, and not just wildfires that are occurring in the Western United States, but wildfires that are burning in Canada as well. So this is becoming a growing problem, not just for Western producers. And there are predictions of further increases in the risk of very large wildfires, especially in the Western United States, and extension in the duration of wildfire season and the area burned by wildfires. So this is not a problem that's going away anytime soon. And in fact, all signs point to worsening wildfires in the coming years.

I saw a recent report by the United Nations that predicted the global increase in extreme fires was supposed to increase by 14% by 2030. So it's kind of a dismal prospect. So the best thing we can do is to prepare for that. Having said that, one thing that I didn't mention yet is that many of the effects that we're seeing on cows, not all, but many of the effects, on both cows and calves, are attributable to both a combination of elevated particulate matter from smoke, but also elevated temperatures, which typically occur simultaneously over the summer. So when producers are applying mitigation tactics for heat stress, that might not be enough to curb the health and production deficits that we see from animals in areas where wildfires are also prevalent at the same time. So this is why we really need research that's focused on wildfire smoke and what strategies, what additional strategies, can we employ to mitigate the wildfire smoke effects in addition to heat stress.

Danae: Thank you so much for being on the podcast. This has been a great conversation.

Amy: Thank you again for having me. I appreciate it.

Danae: Okay Leigh, what did you think about that conversation?

Leigh: I really loved all the different aspects of cow and calf physiology that she was looking at, because you just see how it affects, you know, not just your lungs, but you know, all these various aspects of these animals' bodies. I remember hearing about her a couple years ago when she was first starting to publish some of this work, and I remember having two reactions. One, "Oh, well, that makes sense." Like, I mean, if humans have bad reactions to inhaling wildfire smoke, it makes logical sense that cows have bad reactions as well. Of course, my next thought was, "How is it I never thought of that?" I, because I'd never though of that. I never, it never crossed my mind. I grew up in Montana. I like pass cows all the time. Maybe not dairy cows, but like cows. How is it I never thought of that?

Danae: No, I agree. I had that same reaction and not, yeah, not just cows, but now I'm thinking about like, is it affecting birds? Is it affecting their ability to fly? I was just thinking about all sorts of animals. I imagine anything with a respiratory system, it is negatively impacting in some regard.

Leigh: That's got to be true, right? I mean, obviously once you do the science, but like, it makes sense.

Danae: The hypothesis at least stands up to scrutiny.

Leigh: Yes, yes. I think it's a logical hypothesis.

Danae: I love these random things that come up in episodes that maybe they'll be useful at trivia sometime in the near future. Like, "How much milk does a dairy cow produce in a day?" Like when she said that it can drop by nine pounds, I was thinking like, "Oh, that's like got to be at least half, maybe more of what a dairy cow produces in a day." No, it's like a 10th, which is still, if you're a dairy producer, that's still a lot, but that's crazy. That is so much milk that comes out in a day.

Leigh: I definitely would have gotten that trivia question wrong prior to this podcast.

Danae: Thank you for listening to The Vandal Theory. Be sure to rate, review and subscribe on your favorite podcast platform to help others discover conversations about science, research and innovation at University of Idaho. Email us with research topics, questions or issues you'd like explored in a future episode at vandaltheory@uidaho.edu. To learn more about our research at University of Idaho and listen to past episodes of the Vandal Theory, visit go.uidaho.edu/vandaltheory. I'm Danae Lenz.

Leigh: And I'm Leigh Cooper.

Danae: Thanks for listening.