The Moos Room™

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[cow moos]
Dr. Joe: Welcome to The Moos Room, everybody. Just going to give you a few things to check out. If you haven't done so already, please visit our website, extension.umn.edu. Please check us out on Facebook, we are at UMN Beef and at UMN Dairy. Those are our dairy and beef Facebook pages. Lots of good information there. We're trying to post more and more and more, so if you have a chance, throw those alike. That's all I had for you. Let's get into this episode.
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Dr. Joe: Welcome to The Moos Room, everybody. We are talking about heat stress today. We're not talking about estrus, we're talking about the actual temperature and how that affects cows.
Emily: They're hot and bothered.
Dr. Joe: When they get hot and bothered, yes. At the time of this recording, it's actually cooled off quite a bit, but it was crazy, crazy hot last week for a couple of days, and we've got more in the forecast and so it always seems to catch us by surprise every year, but it happens every year. It gets hot just like it gets cold every winter. We can't forget [chuckles] that it's going to happen every year.
Emily: Like any true Minnesotan, it's not the heat, it's that gosh darn humidity.
Dr. Joe: It's very true. Actually, we'll touch on that later as we get more into this subject. The humidity does play a big part and really, where we should start is when you need to start thinking about all this stuff and when you just need to start preparing for the heat and the temperature change.
Emily: I'm guessing the answer is not when it's already 90 degrees.
Dr. Joe: That's definitely true. I think we're all busy. Dairies especially are busy. It's hard to find that time, but really thinking about checking things and looking at what needs to be done in that March-April timeframe is really when we should start thinking about it to just checking sprinkler systems, fans, making sure everything is in working order. Brad [unintelligible 00:02:10] or do you guys have a checklist that you run through on the dairy as far as checking your heat abatement strategies?
Bradley: No.
[laughter]
Emily: [unintelligible 00:02:19].
Bradley: Definitely, that is a surprise. No, we're outdoors, so we have a different mentality to the heat stress really, we try to manage it. We have fans in the milking parlor and stuff, so we make sure those are all running and moving air well, but for a grazing dairy, heat stress is a little bit different than your regular tie-stall barn or free-stall barn.
Dr. Joe: That's true. I guess there's some big concepts that still apply to both. One of the reasons that we put dairy cows in confinement is because now they have shade all the time and that's different on a grazing dairy. Definitely, like we talked about in episode 11, you have solar panels that you also double as shade for the pasture. Do you guys purposely have trees in certain areas or make sure that you make paddocks where there's always shade available?
Bradley: Yes, yes. We have it on a lot of our pastures, but not everyone. For grazing dairies, a lot of us use trees. That's probably the biggest thing is trees for solar, there's many different ways you can develop solar panels. I've been on some farms where they've built their own little shade cloth for out in the pasture. There's ways to get around it in a grazing dairy, but it's probably more difficult because even if they're under the shade, they're probably still heat stress because their solar radiation is still on those cows.
Emily: I don't want to get way too into the weeds on this, but thinking about grazing dairies and Bradley, do you find that because you do the crossbreeding, and I do believe some of the breeds you use, one of the things they tout is they're a little more hardy and can handle a little more heat. Do you find that, or it's a cow-by-cow basis, just like it's with people?
Bradley: Yes, Emily, I think it's more of a cow-by-cow basis. Yes, we see all kinds of our cows in heat stress, whether it's a Holstein or a crossbred, they can all be heat stressed and even our Jersey-sided crossbreeds become heat stressed. It's different where some cows will be heat stressed and the next one standing right next to it doesn't seem to affect her as much.
Dr. Joe: It's probably very similar to people. Some people just love the heat. I am not one of those people, my wife is. She's perfectly happy with it being 80, 85 degrees full sun. I'm much more comfortable when it's 60, 65, and in the shade. I'm sure it's different just like that for cows. The big difference between people and cows though is when they start to see that discomfort from heat, cows generate a lot of heat just because they have this giant fermentation vat in them that generates heat and they start to experience heat stress pretty early.
We're talking 72 degrees, 50% humidity, that sounds just about perfect for most people. That's already right at the limit that we start to see cows actually get heat stressed and start feeling too hot. That's a big, big difference. I think that's something we need to think about. If you're comfortable in the barn, it doesn't necessarily mean that the cows are. Let's talk humidity because it does play a big, big difference. Emily was-
Emily: That gosh darn humidity.
Dr. Joe: -was joking about it earlier, but it's true. It really is. It does make a big difference. What we use with cattle usually is temperature humidity index, which is a measure that takes into account the humidity level with the temperature and gives you a score for the temperature humidity index that is more accurate for what the cows are experiencing. That threshold is set at 68, so when the temperature humidity index gets to 68 degrees or 68, then that cow starts to be heat stressed and it goes up pretty quick from there.
If you get really high humidity but a moderate temperature, you're actually looking at a cow that is in quite a bit of danger health-wise and definitely is going to lose some production. One of the ways we can tell that is counting respirations or actually taking a body temperature. Now Brad's probably going to say something about a sensor at this point.
Bradley: Yes. There's sensors for that kind of stuff. We can put in cows and measure that. I usually have--
Emily: [unintelligible 00:07:11].
Bradley: Exactly. Exactly.
Emily: We'll figure it all out.
Bradley: No, it is quite interesting. It's not perfect for trying to figure out body temperature. At some point, you can measure body temperature if you do it the old-fashioned way with a thermometer but that takes a long time to measure a lot of cows. Here, I'll give you my example of our sensor, but we have a bolus that we can put in. It's smaXtec Bolus and it measures the internal body temperature. It's a lumino reticular bolus that you can put in a cow and it measures the heat stress. Even, was that last week, we had some major heat stress in Minnesota. It was hot, almost 100 degrees here in Western Minnesota, and one cow, I looked up, she had a internal body temperature of 107�.
Emily: Wow.
Bradley: That's hot. She was under some massive heat stress. That is hot.
Dr. Joe: I guess we should point out just in case there's someone out there that doesn't know the normal temperature for a cow, it's between 101� and 102�, that's normal for a cow. 107 is way, way, way too hot.
Bradley: Yes, way too hot. Today she's measuring, let's see, 103, so she's much better. Usually the internal body in the rumen reticular, it's going to be a little bit warmer than 101� but yes, [unintelligible 00:08:45].
Emily: 107 is still too hot.
Bradley: 107 is pretty hot and it flags those cows and we can spray them or try and do some measures to help them with heat abatement but that cow is different. That was the cow that was heat stressed. If you look at some of the other cows, they didn't have those temperatures. Some of them were heat stressed, but some were at 102, 103, but not like that. She was, by far, the warmest.
Dr. Joe: The best way for me is counting respirations. I think that it's easier than catching every cow. There's no stress associated with putting them through the chute or trying to figure out how to catch them so you can take a body temp. For me, I like counting respirations and you can tell right away where your cows are sitting based on how fast they're breathing. In normal, we like to see 40 to 60 breaths per minute out of a cow. I would say that you can even get quite a bit lower than that. If you're above 60 breaths per minute, then you start to be [unintelligible 00:09:51], that's a mild heat stress and it just goes up from there.
If you get cows over 100 breaths per minute, you're really getting pretty close to an emergency situation where you need to do something to cool those cows down because you're going to have some serious health issues or even enough complications that lead to death, so count those respirations, check on it. If you know you're seeing a problem, then you need to figure out other ways you can cool your cows down, other strategies you can use, whether that's fans or sprinklers or some of the other things we'll talk about here in just a second.
Emily: I have a question.
Dr. Joe: [sighs]
Emily: Outside of the counting respirations, which even too, sometimes, you can just physically see when a cow is huffing and puffing pretty hard, are there other physical signs of the cow's heat stress? We think of some of the other things we look for when a calf has scours or a cow is sick, is there anything else like that that we can look for in cows to know if they're heat stressed or not?
Dr. Joe: Well, their physical appearance is definitely, it's hard. It's hard to notice anything that's too noticeable besides an increase in respirations until it gets to a really severe level. For me and when you're looking at an individual cow, it's always respirations, first body temp if you can get it, but I like respirations because you don't have to handle the cow. You can count it by looking at it. If they're truly heat stressed, you've probably seen it on those hot days when they get their feet spread apart and they extend their neck out and they really start to breathe with their mouth open.
Emily: Know they even have their mouth open sometimes.
Dr. Joe: They pant. Yes.
Bradley: Pant and their tongues hanging out.
Dr. Joe: There's other things they do too. You'll see a lot more perching cows that just don't want to lay down because they want all that air movement underneath them trying to cool them off. As you're probably aware, if you don't protect your waterer, they will stand in it and mess with it and get it all dirty. There's other things, subtle things like that. Most of it is, is a lack of lying time, the respirations and then if it gets really bad, you see them pant.
Bradley: Well, when I think we think about cows, most people were thinking about older animals doing that, but baby young calves will do that as well. I noticed that the other day when it was 100 degrees Fahrenheit here in Morris, we had calves that were 50, 60 days of age panting and they were just hot and uncomfortable. It was unbearable to watch even just calves do it. They were indoors not out of the shade. They had shade, they weren't outside and they were still just hot. It was yes, tough. It affects everybody.
Dr. Joe: Yes. It can affect anybody. I think the biggest thing to remember too is that if for whatever reason you're there and you're hot and you're uncomfortable, it's even worse for that cow or that calf. You just got to keep that in mind. Anytime you're in an environment and you are uncomfortable, that cow is more uncomfortable than you are. You got to figure out a way to try to put in some heat abatement strategies to lessen how severe that gets because you're not going to avoid it. They're going to get hot. There's no way you can avoid it entirely.
Emily: I have a question and it's related and it probably stupid so you can cut it out if you want.
Dr. Joe: No, no.
Emily: Do cows sweat?
Dr. Joe: Kind of.
Bradley: Yes, kind of, yes.
Emily: Isn't what we're taught like, "Oh, pigs don't sweat," but I know horses sweat after you've been riding them and they'll be all sweaty.
Dr. Joe: Yes, they'll lather up. They may sweat, but they usually, I don't even know if they have sweat glands. I'm completely blanking on my anatomy right now.
Emily: Oh my gosh. Have I stumped the doctors?
Dr. Joe: I think so.
Bradley: You have.
Emily: Oh.
Bradley: Ruminate on that.
Emily: Setting moments in the podcast, Joe. People need to know.
Dr. Joe: Yes, they do have sweat glands.
Emily: Oh, does it say where they are?
Dr. Joe: I don't think--
Bradley: They have sweat glands, but they don't have enough to make a difference, we'll call it that. The reason they pant is just like why a dog pants. A dog doesn't have sweat glands except for in its paws or in its feet. They pant to get rid of that excess heat just like a cow has to resort to that if they get too hot. They have sweat glands, but they either don't have enough or they're not active enough to actually cool that animal down by evaporation. That's why we have to add water to the situation to help them cool themselves. We do that with sprinklers usually and soakers.
Then I think soaking is the key word because what we want is we want that animal to be not just wet on the hair, which is actually worse for the cow. We've created now not only an air barrier with the hair but also a water barrier if we don't wet that animal to the skin. We really want to soak them, or we want to get them wet to the skin and then there has to be a break. You can't just have a water all the time because what actually cools them is that evaporation of that water, taking the heat and evaporating and transferring that, that energy.
You have to have a break in your sprinklers. If you've ever been on a dairy, they come on and off. That's the reason is that they have to have an off period for it to actually work. That's tough in Minnesota because like Emily keeps saying, it's humid and--
Emily: Gosh darn humidity.
Braley: The more humid it is, the less that process works.
Dr. Joe: We're talking about sprinklers and all that fun stuff. I saw some cool research from the University of Wisconsin-
Braley: [unintelligible 00:15:48].
Dr. Joe: -and [unintelligible 00:15:49]. They were showering cows in the milking parlor. As they come into milk in the parlor, they would turn on and shower them with a lot of water, make them just soaking wet. Then when they went out, saw a reduction in heat stress. Obviously, it's very temporary. It lasts a few hours but it may help those cows a little bit. It's cool. I have showers in our milking parlor as well and we'll do a study on those to see what it looks like in grazing cows at some point.
Bradley: I think--
Dr. Joe: Just a cool little thing. Besides, everybody thinks about sprinklers and having to soak the cows in the stalls and stuff, there's maybe other ways we can do it as well.
Bradley: Yes. The big thing you have to be careful with no matter where your sprinklers are or how you're getting those cows wet is you really, there's definitely like a Goldilocks situation where not enough is bad, but too much is also bad because if you get enough water dripping down from that cow and it ends up on the udder, you just created the perfect environment for mastitis issues to ramp up especially when we're talking about hot, humid weather. You've created just a perfect spot for some of our coliform mastitis to really blow up. It's a tough deal, but that's why you need to make sure things are working properly so early to make sure everything is dialed in the way you want it to be.
Emily: Yes. I would add on that maintenance piece for it too is checking that they're aligned the right way and dripping or sprinkling where you want them to because I have been on farms and seen where cows will lick them because there's water coming out and then they'll get them turned or moved around and then they're dumping water into the feed or getting it somewhere it's not supposed to be. I think that that's one of those really minor details but also something you need to be aware of because it's not just getting the water there but getting it on the right part of the cows.
Bradley: That's a good point, good point.
Dr. Joe: Yes, because it definitely can soak the feed bump pretty quick if it's not pointed the right way.
Emily: Especially if you have Jerseys, you're getting in trouble.
Dr. Joe: Oh, yes.
Emily: Check it every day.
Speaker 1: That's probably a good point. At least walk it once a day to make sure they haven't screwed something up by licking everything. One of the ways you can help that sprinkler system to work is by having air velocity on the cows. If you think about it, if you don't have central AC, the first thing you do is get a fan. You're just trying to get some air movement to cool yourself down and it's no different for cows. We like to see pretty good air velocity at cow level to try to help with the evaporation but also to cool, physically cool that cow by having some wind move past her.
It's really, really effective if you can keep the air velocity at cow level. I keep saying at cow level because you can move air around in the barn, but if it's not pointed at the cows, it doesn't really matter all that much for that piece. We like to see, I tend to like to see seven to 8 mile per hour winds at the cow level. Not only because it helps her cool very effectively, but that's the wind speed we need to also keep the flies off the cows so I like to see that wind speed.
Then, don't forget that all this still applies to the holding pen, which Brad mentioned that he has fans and things in the parlor and the holding pen and that's really critical. You think about how bunched up those cows are. Usually, they're in a tight space and they get heat stress very quickly and they can be there for quite a long time depending on how fast you milk. Right, Brad?
Bradley: That's right, that's right. Might take a lot longer to milk than what it should.
Dr. Joe: Yes, so yes--
Emily: Well, that doesn't happen.
Bradley: You have to be aware of that and just make sure that you're accounting for it in that tight space. I'm sure you guys have seen it all the time, those holding pens and parlors are sometimes retro-fitted from older buildings and they can get real tight. You got to be pretty creative for how you get fans in that space and keep them out of the reach of Jersey tongues and everything else that are going after them.
Emily: I would say, especially when you're in a retrofitted tie-stall barn just with how low those ceilings are, I've seen a lot of creative fixes that people have done to make sure that there's air getting over the cows and being moved across them as well so that's an important part too. I also want to add, Joe, you talked about getting the fans at cow level. I have been on farms where, to no one's fault, but it seems like some fans are maybe placed with the idea that it's more for human comfort or I've seen like in parlors or something, milkers will move fans if they're able to move or they'll do these different things.
I think it's also a good management practice to also when you're thinking about fans for your cows, think about them for the people working as well, especially milkers, I would say because parlors get hot. We're drifting more into HR territory here I guess. Just because I've seen cows missing out on getting the airflow they need because people are moving the fans for themselves.
Dr. Joe: You can't forget that. We're trying to make the cows as comfortable as we can, but your employees also need to be able to work in comfort if at all possible. If you can plan for that, like Emily said, you can maybe prevent some of those situations where there's competition for that comfort.
Bradley: What about drinking water?
Dr. Joe: Yes, continuing with water, we got to figure out, cows drink a ton of water, it's a massive amount and it goes up pretty much linearly as it gets hotter. If a cow's milking 80 to 100 pounds a day, she's drinking 25 to 35 gallons of water per day if it's 85, 90 degrees for the environment temp. That's a lot of water. They drink it all right after milking for the most part. Brad, you probably see that on the dairy. They come out of the parlor and they go immediately to the water and the feed and back and forth.
Bradley: They do. One thing I've always thought of and I've heard other people have asked me about, "Does it matter the temperature of the water?" Like when we're out on pasture, and if it's 100 degrees out and the sun's beaten down, a lot of people have waters on pasture, I'm fairly certain that water is probably 100 degrees as well or close to, it if not hotter.
Emily: Bathwater.
Bradley: Exactly.
Emily: Refreshing.
Bradley: [chuckles] "What about cool water? Is cool water better or will they drink warm water?" I don't know, I get that question a lot and I don't have a good answer.
Dr. Joe: I think the important piece is water, just availability, how much is there. Do you have enough space so everyone can drink? Do you have a good enough refill rate that a cow can't drain it so easily that there's just not water there available for long enough? I would think the temperature would matter.
Emily: I would say cleanliness over temperature.
Dr. Joe: Yes, I would put temperature--
Emily: Temperature still is important.
Dr. Joe: No, you're spot on. I think there's a hierarchy to it. It has to be available first. There has to be enough of itand then it should be clean. Then temperature is pretty far down the list I would guess. In the winter though, it's the same way. I'm sure they don't like cold water in the winter. They prefer to drink hot water. I just don't know how practical it is to run heated water.
Bradley: Heated water. Well, we run space heaters, why not? [chuckles]
Dr. Joe: It's probably cost about the same.
Emily: Everyone gets a thermos.
Bradley: That's right.
Dr. Joe: Thermos, a 35 gallon thermos?
Emily: That's it, like thermos pales.
Dr. Joe: Oh man.
Emily: Million-dollar idea.
Dr. Joe: Emily's going to quit the podcast now. She's got her idea.
Emily: Yes.
Dr. Joe: [chuckles] The water is important, not only the cooling cows on the outside, but they got to drink it or they lose all ability to regulate their own body temp.
Bradley: What about the issues? What are we supposed to watch for? If we're trying to cool cows, obviously, it's not going to be perfect, right?
Dr. Joe: No.
Emily: With that, I would ask, what do you think are the most common mistakes people make?
Dr. Joe: Well, I think the biggest mistake is what we talked about already. People just don't prepare ahead of time. You end up at it's 95 degrees and your sprinklers aren't working because we didn't check them ahead of time. Same thing with fans, fans lose a lot of capacity the dirtier they get. They can work at half capacity if they're dirty. Just common maintenance things are the biggest problems to watch out for.
Then we touched about it, making sure the air flows at cow level. There's a lot of times, and I see this a lot in tie-stall stanchion barns where you're looking at good airflow in the alley and it feels good for the people being in there, but if you step into the stall where the cows are, it's hot.
Emily: It's miserable.
Dr. Joe: Yes, so you got to make sure that you're standing and kneeling or sitting or trying to figure out where the cow would be and make sure the air is there also. If it's not, then it's time to make some changes or call in an expert to look at how to fix that. Sometimes, it's as simple as tilting those fans down so that they actually point down at the cows and they're not just mixing air up above the cows. That's probably the big ones, trying to make sure. Now, with sprinklers, it's all about pressure and the right nozzles, and like you said, checking them to make sure the Jerseys haven't spun them around or broke anything.
Emily: I also think that fan selection is where people can sometimes go wrong or you need to think really critically about that. I've seen just in the calf farm, they had variable speed things, but they didn't have those set right. All the calves were getting sick and because they weren't running at the right temperatures and speeds so things like that or just being mindful of what is the ventilation system in your barn already. Are you cross-vent? Are you tunnel vent? Are you natural vent? Then, are you getting fans that support that plan, or are you putting in fans that are in conflict with that?
I think sometimes we get so caught up in as much airflow as possible and then what we're basically doing is just creating stale air because it's being pushed so much, it's just there and can't be moved across the cows in the right way or you have a lot of exhaust and not enough inlets or vice versa.
Dr. Joe: That's a huge, huge issue and when we're really getting at is air exchanges. In the summer, we just basically want as many air exchanges as we can of the air that's in the barn to out the barn and then bringing in fresh air. Really, we want to see that happen at least 60 times an hour where all the air in the barn leaves and is replaced by new air. That's a huge way to keep the environment cool. It is difficult though if you pick the wrong fans to it can be very simple and I've seen it a lot where you have a tunnel-vented system, but your circulation fans are working against the tunnel vent.
Now you've changed, you've just put the fans facing the wrong direction or you have fans trying to blow against prevailing winds, which isn't very efficient either. It can be pretty complex but there's a lot of people out there that can help the engineering department here at the University of Minnesota with extension, can definitely help. If you need to call Kevin Janni or Aaron Cordes, I'm sure they're willing to help if this is something you're concerned about.
It can be fairly complex trying to get those air exchanges right and get the air moving the right way. I've got cool videos when I'm with my buddy and we smoke barns with insect fogger and you fill it up with mineral oil. Then just so you can see where the air goes and it doesn't go where you think it goes a lot of the time. It can point out some problems if that's something that you think is wrong.
Emily: Something that our colleague, Jim Salfer told me that I've never forgotten, and a lot of people say it, is that air is lazy, so it's going to follow the path of least resistance. Like you said, Joe, when you are putting in fans that are counteracting what the ventilation setup of your barn is, you're not creating a path of least resistance for this air. That's where the exchange rate is going to go down.
I also think people need to think about their barns. Do they have an open ridge or are they using mixing fans? I'm a big believer in baffles personally, all these different things that you can do. Joe has this look on his face about the baffles comment. I don't even know if I want to know.
Dr. Joe: Baffles, in a Crosman barn-
Bradley: [unintelligible 00:29:55].
Dr. Joe: -baffles can be helpful, but they can also cause a lot of issues. It's just like the rest of this. I guess I don't have anything against baffles, they just need to be set up correctly or they're actually counterproductive. Does that make sense, I guess? That's my problem with baffles. I see a lot of them installed incorrectly and in the wrong spot and they're actually hurting rather than helping.
Bradley: That's right. They can hinder a lot of air movement if they're installed incorrectly.
Dr. Joe: All right. I think we've given everybody enough to think about as far as heat abatement strategies and what you need to be looking for. Really, it's about getting the proper air exchange for ventilation, moving air or around the cows at the correct level in a way that doesn't counteract your overall ventilation strategy. Potentially adding some kind of cooling with water, which, like Brad was talking about, doesn't necessarily need to be sprinklers over the feed alley. It can be in the parlor and there's other strategies that we're experimenting with and providing enough drinking water. That is huge. That is huge.
It doesn't take long to go out in the pen. Make sure you feel air in the right spot that is blowing at the correct angle. Make sure the cows are comfortable. Just keep in mind that if you're uncomfortable, the cows are uncomfortable for sure. We have an article that is specific to this topic called Preventing Heat Stress in Dairy Cattle that Kevin Janni and I put together. You can find that at extension.umn.edu. If you have comments, questions, scathing rebuttals, hate mail, please send them to themoosroom@unm.edu.
Emily: That's T-H-E-M-O-O-S-R-O-O-M@umn.edu.
Dr. Joe: Thanks, Em. We will catch everybody on the next episode. Thank you for listening.
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Emily: It's not the heat, it's that gosh darn humidity, that gosh darn humidity, that gosh darn humidity. You're welcome, Joe.
Dr. Joe: Thank you.
[music]
[cow moos]
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