Maine Farmcast Episode 13: Heat Stress Considerations for Dairy Farms with Dr. Bethany Dado-Senn
In this episode of the Maine Farmcast, Dr. Glenda Pereira, assistant extension professor and state dairy specialist for the University of Maine Cooperative Extension, has a conversation with Dr. Bethany Dado-Senn about heat stress on dairy farms. Dr. Dado-Senn grew up on a 500-cow dairy farm with her family in northwest Wisconsin. She attended the University of Wisconsin-Madison where she earned her bachelor’s and Ph.D. and the University of Florida where she earned her master’s. Dr. Bethany Dado-Senn is a calf and heifer technical specialist for Vita Plus, providing technical expertise to help producers raise the next generation of their milking herd. She resides in northwest Wisconsin with her husband and daughters, and is the calf manager for her family dairy farm.
Episode Resources
Transcript
Glenda Pereira: 00:15
Welcome to the Maine Farmcast. This is your host, Dr. Glenda Pereira. I’m an assistant extension professor within the University of Maine Cooperative Extension as well as an assistant professor within the University of Maine School of Food and Agriculture. On today’s episode, we have a featured guest reigning from the Midwest.
Glenda Pereira: 00:35
I’m excited to have, Dr. Bethany Dado-Senn on with us today, who is a calf expert. And without further ado, Bethany, take it away, and thank you again for, coming to share a lot of good information today with our listeners.
Bethany Dado-Senn: 00:53
Awesome. Well, thanks so much for having me, Glenda. Hello, everyone. Like she said, my name is Bethany, and I am a calf and heifer specialist with a regional nutrition company called Vita Plus. And we are based out of Madison, Wisconsin, but I serve farmers across northern Wisconsin, all of Minnesota, and ducking down into Iowa a little bit.
Bethany Dado-Senn: 01:11
My background is I actually met Glenda during our time in graduate school. So I was a master’s student at the University of Florida and then did my PhD at the University of Wisconsin Madison, where we looked at the impacts of late gestation heat stress on both the cow and her calf, and then also, kind of, heat stress throughout the pre weaning period on calf performance. I’m a big believer in combining the science of dairy management with the actual practical management component, as a majority of my time is spent on farm kind of troubleshooting issues with dairy farmers and coming up with solutions that make most sense for both the farm and the animal. So really happy to be here today to talk about that passion of heat stress.
Glenda Pereira: 01:56
Yeah. So we’re gonna be talking about a lot of the research that you conducted at Wisconsin and Florida. And and then, obviously, you’re passionate about the application of science to the field because your parents are dairy farmers. You yourself are a dairy farmer. So so there’s that tie tie back to the farm.
Glenda Pereira: 02:16
And you just wanna give the listeners a bit about your your background. So you you are a dairy farmer.
Bethany Dado-Senn: 02:23
Yes. Yeah. I suppose I should mention that. I am one of you. We, farm in Northwestern Wisconsin about an hour and a half from the Twin Cities of Minnesota.
Bethany Dado-Senn: 02:33
My parents own a 500 cow dairy with registered Holstein dairy cattle. And my role right now is assistant, calf manager. So I help eat cows in the morning, but it’s a really great way to think about the tips and tricks that I help farmers apply on their own operations and and try them myself. You know, what works, what doesn’t work in our individual hutch system and our pasteurized milk system, and how do our cats perform? What metrics are most important for our operation, and how is that the same or different for other farms?
Bethany Dado-Senn: 03:05
So because it takes us a while to feed, I have a lot of time to think about those things as as I do that. So, hopefully, you can hear some of that as we talk about the the science today.
Glenda Pereira: 03:16
Yeah. Great. So like like we’ve discussed, we’re gonna be talking about heat stress today. And give us sort of the the objective and the why behind, your team and and your adviser, doctor Jimena Laporta, wanted to pursue research and heat stress and how it impacted calf performance, and then, of course, that’s gonna impact 1st lactation performance as well?
Bethany Dado-Senn: 03:41
Sure. So I’ll take it all the way back. There’s been kind of this dry period heat stress work since the eighties, but it’s really taken a deep dive since around 2010, when our colleague, Dr. Geoff Dahl, and his then student, Dr. Sha Tao, looked at the impact of both, photo period and heat stress on dry cow performance. That was just background before he dove into this. And they were really shocked to find this, like, really persistent impact on milk yield in the next lactation.
Bethany Dado-Senn: 04:12
And it makes a lot of sense if we think about what’s happening during the dry period. The mammary gland is undergoing cell death and then regeneration. And when you have something like heat stress, that gets in the way of that. So, it kinda started there. And then when Dr. Jimena Laporta joined the faculty at Florida, she really wanted to take a deeper dive into some of the cellular and hormonal consequences that go along with that.
Bethany Dado-Senn: 04:34
Now what is really impacted by hormones during pregnancy? The calf itself. So kind of during our tenure at Florida and then when we transitioned to Wisconsin, we were looking at the consequences on that gestated calf. So we do know that calves born under immunodar heat stress are smaller in size and stature. They have reduced starter intakes and lower average daily gain.
Bethany Dado-Senn: 04:59
They’re more immunocompromised. They don’t absorb their immunoglobulins as well. And then, most importantly for us, kind of that spark, if you will, for us is the fact that the mammary gland of these in uteroheets stressed heifers is smaller starting right away after they’re born. And there’s changes in within the the tissue itself so that it has reduced synthetic capacity. It doesn’t make milk as well.
Bethany Dado-Senn: 05:22
And that, again, starts right away from birth, and we see it persist all the way up into lactation. So that’s one of the main contributing factors why if you have a dry period heat stress dam, her calf will make less milk when she becomes a 2 year old. Yeah.
Glenda Pereira: 05:37
And and so heat stress, like you mentioned, is something that’s been explored before, but maybe now that we have longer periods of heat stress events than than we did before. For example, to give you some background, like, here in Maine, a lot of the houses don’t have air conditioners or heat pumps installed because we didn’t have the heat events that we do today. And so now you see a lot of the houses being built with AC units because it’s it’s just a changing climate. And so, obviously, mitigating heat stress is gonna be something we’re gonna be talking about, because it has, you you know, significant impacts. And so do you do you see some farmers saying, well, you know, that was in Florida, and we’re here, you know, in Wisconsin or Midwest or Maine?
Bethany Dado-Senn: 06:26
Heck. Even I say that. I am cautious sometimes with what I translate up into the Midwest and and probably to Maine as well, in terms of what it’s going to look like in our more continental climate. So Florida, as as most of your listeners are probably aware, is kind of more of a subtropical climate. So what that means is that, they have a very long persistently humid summer, and I can attest that that is true.
Bethany Dado-Senn: 06:52
We would usually start our Easter studies in May, and the hottest month in general is actually usually September. And I could continue my studies through November, no problem, and still have heat stress. So that would be classified under what’s more considered a chronic heat stress event. There was no reprieve. And I think, actually, one of the main consequences that we don’t think about with all that is the fact that, in Florida, it does not cool down overnight.
Bethany Dado-Senn: 07:18
We don’t necessarily need many, many days where it’s cool or, like, pockets of days. But if we have at least hours of time overnight where the temperatures cool down, But in Florida, they didn’t have that opportunity because it never really cooled down to the degree where that would help. And so I think that’s a big reason why the consequences for that in utero heat stress in Florida were so severe because there was really no escape. Conversely, up in the Midwest and up in Maine, we have more of a continental climate, which means we have hot humid summers, but they are shorter in nature, which means that when we do have heat stress events, they’re probably a little more acute, which is basically like short bursts. Now we don’t have the research to say, like, what’s the consequence of acute heat stress bouts on on, dry period heat stress.
Bethany Dado-Senn: 08:14
We know for lactating cows that there is actually almost more severe consequences on quick drops in milk production. But for that dry cow, we can’t say. What I can say is that we did do a study where we looked at heat stress during the dry period, either the, 1st 3 weeks of the dry period, the last 3 weeks, or the entirety, and all three groups saw reductions in milk yield in the next lactation and smaller calf size. So even if you only have a heat stress window of 3 weeks or less, you can still expect that you’re gonna see some negative consequences on that cow and her calf.
Glenda Pereira: 08:52
I think it just reiterates the fact that there needs to be some mitigation or farmers need to be thinking about some ways to mitigate heat stress because I don’t think these acute events, especially in the northern hemisphere, are going, to go away. And farmers in Maine here are really excited about the cool weather this week and next week because we have been, you know, reaching up, near to 90 degrees consistently, and it’s it’s been miserable for the cows and for the calves. And so this kind of leads me into my next question. What are the best ways to mitigate heat stress during the dry period? And then maybe describe what what the best combo because you you explored some, different methods.
Glenda Pereira: 09:36
Right? Shade and and, mist or or water versus not using water and just using shade, if I remember correctly. Yeah. And actually you bring up a good point. So when I talk about like our in utero heat stress versus in utero cooled groups, that in utero heat stress group did actually have the shade of a barn of a barn.
Glenda Pereira: 09:56
So this isn’t even like your pastured dry cows that have access to nothing. It even with shade, we considered that still heat stressed in Florida.
Bethany Dado-Senn: 10:05
Now that being said, up in more of the continental climates, I usually do push for shade and fans as kind of the the start, the bare minimum. I really like any sort of pregnant animal to be housed with access to shade And I do respect that pasturing dry cows makes a lot of sense in a lot of different scenarios. But at least be offering shade cloth or and or, tree lined shade for your animals, that’s a great first start. But the addition of active ventilation through fans can make a really big difference. There’s some work in lactating cows on, like, what the air speeds need to be.
Bethany Dado-Senn: 10:45
And, basically, they found that if air speeds are at 1 meters per step meter per second, there is advantages in thermal regulation and milk yield and dry matter intake. And that’s only incrementally improved if we go up to, like, 2 and a half meters per second. So do that mental math to get to miles per hour if you need to. That’s, what that study suggested. And I would say the same thing on the dry cows.
Bethany Dado-Senn: 11:08
We don’t need to necessarily be blasting the cows, but we do need some air movement across the animal. Last point is you mentioned kind of that water soaking. Now if we’re in more of an arid climate like Arizona, they’ll do a lot of misting. But if you have any sort of humidity, you do wanna go for a thicker droplet. So that would be more of a sprinkling.
Bethany Dado-Senn: 11:30
I have been saying in the Midwest that I’m not sure we always need sprinklers over the feed bunk because of the overnight cooling, but I don’t have any research to support that. So if somebody wants to go in and put in a sprinkler line, I will not be upset with them. It can only help. So there there is a study from Geoff Dahl’s group and his, grad student Leticia Trevisan that looked at smart soakers. So instead of just doing it on a time basis, they’ll do it on, like, motion activated.
Bethany Dado-Senn: 12:01
And they show that those were equally effective. So from a efficiency climate standpoint, I I would love like, my perfect system would be a freestyle barn with basket fans and smart stokers. If anybody’s building a barn, there you go.
Glenda Pereira: 12:18
That’s great. Yeah. And, I wanna remind folks that it’s important to have the fan and the cooling. So if you have just water, the cow isn’t really getting cooled down. It’s the addition of the the movement of air that’s really helping, cool her down.
Glenda Pereira: 12:35
Yes. So So so so both work, in concert. It’s it’s not one or, the other. Well, obviously, you can just put fans in it, and that works really well for air movement. But if you’re implementing, a soaker, make sure that you have that air movement dialed in.
Bethany Dado-Senn: 12:51
Yep. And the same, I guess, I should say too. I mentioned basket fans, like cross ventilated or tunnel ventilated barns would be equally as if not more effective too, compared to, like, this naturally ventilated basket fan scenario. A great resource for folks there is the Wisconsin Dairyland Initiative. It is not just for Wisconsin dairy farmers.
Bethany Dado-Senn: 13:09
They have really great resources on fan spacing, fan speeds, all of that, bunk bunk size, all of that to help kind of guide your decision making with facility design. Fantastic. So I I guess you just shared
Glenda Pereira: 13:24
you just answered my next question because I was gonna ask if what is one tool or resource that’s free and that you use every day to sort of potentially help your farm or your farmers that you work with in your service provider role, to improve their bottom line.
Bethany Dado-Senn: 13:40
The other resource I would say that’s kind of more like literally a day to day that I think sometimes we don’t think about is actually water access, which isn’t, you know, it’s not inherently free, but it’s pretty darn close. And I think sometimes we forget that that’s the number one nutrient for both calves and cows. Continuous access to clean water is going to make a huge difference during these heat waves. So that looks like, you know, proper bug space isn’t the right word, but proper spacing at at the water. So every cow has excess.
Bethany Dado-Senn: 14:14
And then on the calf side, I really like, to discuss offering warm water right after milk feeding, and then follow that up with some cold water in the buckets that’s available throughout the day.
Glenda Pereira: 14:28
Yeah. I I agree because, water drives a dry matter intake. So if they don’t have any water, they’re not gonna be as motivated to eat. So so water really helps drive dry matter intake, which is really important even more so during periods of hot stress because they’re not gonna be eating a lot.
Bethany Dado-Senn: 14:48
Right. Yeah. So every bite counts to help maintain milk production, maintain growth, but also, you know, thermal regulation costs energy. So they need that for that too.
Glenda Pereira: 14:58
Yeah. Well, great. Thank you so much, Bethany again for, talking about heat stress and some of the way some of some of what we need to be thinking about, not only calves, lactating cows, but even prioritizing the dry period for cows because it’s gonna have a big impact on first lactation performance and growth fact obviously, the growth, factors, when those calves, when those dams have calves and those calves are raised, it’s gonna impact their performance during, the rearing period. So it’s it’s really important. And with that, that that’s the end of our episode.
Glenda Pereira: 15:34
So thanks again.
Bethany Dado-Senn: 15:36
Thank you.
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