Episode 182 - Flooding feed yards and hairy heel wart (digital dermatitis) - UMN Extension's The Moos Room

Dr. Joe Armstrong: Welcome to The Moos Room everybody. Dr. Joe Armstrong here. Today, it's just me, Brad and Emily are at Farm Fest and I was there yesterday, so they're not around to talk today. They're busy working the booths down there. I hope everyone got a chance to see them. By the time this comes out, Farm Fest will be over, but I'm sure everyone had a great time. Great event. Glad that I got to go for at least one day. All right, down to business. What are we talking about today? I've been talking to a lot of people between the Minnesota Cattlemen's Summer Tour, Farm Fest.
Lot of questions come in with the heat, the drought, all sorts of things, but I want to address one thing. I was lucky enough to talk about this with Ryan Vos on KJOE radio. I want to expand on my thoughts. We'll get right to the beginning and start over and explain the whole deal. There's a practice, and I think it's fairly common or more common than I realized originally after talking to a lot of people in the area, especially in southwest Minnesota when we're on a feed yard, that I think has great intentions, but might be causing long-term problems and is really a really short fix for the heat, but is setting everything up for failure later when we talk about overall health of our cattle.
What are people doing? Talking to people in southwest Minnesota, what I'm finding is when it gets hot, there's certain feed yards that allow their feed yard to become flooded on purpose. They're letting waters overflow or they're adding water to the pen to create a pond, basically, or someplace for the cattle to be able to cool off. Now, in theory, for the heat, it might help and it might work well. It allows the cattle to access water as needed to cool off, but what I worry about a lot is there's so many health implications from this practice that make me incredibly nervous.
There is really no way around it, no way to talk about this in a non-controversial way. I don't think so. If anyone would like to talk with me about this or discuss it, I'm more than happy to do so. Please, send your emails in or call me, happy to talk about it. When we purposely create mud, which is what we're doing, it makes me nervous. We spend so much time trying to avoid mud at all costs, not only because of the production losses associated with mud, but then also hoof health reasons for avoiding mud. If you're creating standing water, now you've created a risk for certain diseases, because cattle are certainly not going to just drink from the waterer if they've got standing water available right there.
Now, later we'll get into what we can do for the heat and what we should put our time and energy into, in my opinion, rather than flooding the yard. Let's talk specifically about digital dermatitis or hairy heel warts as an example of why we shouldn't flood our yard. We get a lot of questions, especially on the beef side, the feed yard side about hairy heel warts, where do they come from? How does it happen? What's the disease process? How do I bring animals onto my farm and not get it?
Why does a one pen always break? Is that pen actually infected or what's going on? All sorts of questions that I think I have some answers for, but we're still honestly figuring out with the research. When we look at digital dermatitis or hairy heel wart, what the disease process looks like now and our understanding of it now is much different than it originally looked like.
We love simple answers, right? Why not? Simple is great. If there was one bug and that caused the disease, boom, done. Figured that out. Forget everything else. As is the case with a lot of disease processes, that is not how digital dermatitis works. When we talk about hairy heel wart, the model is quite complex and it starts with certain bacteria colonizing and then different bacteria taking over. There tends to be one key bacteria that then tips the scales and allows things to move forward, but it's a multi-variable multifactorial disease with lots of players.
Anytime we have this super complex disease process, a lot of times what's most helpful is to look at the prevention side and really focus on that for preventing the disease, looking at the disease process from the very early stages and starting there. That is going to be the key. When we have all this complexity in it, treatment becomes often quite difficult. We don't have a vaccine because there's not really a specific target that we can focus on. Prevention is key, and for that, we look at risk factors.
What is associated with these lesions happening? What's associated with digital dermatitis? The very first step in the disease process is having some kind of break in the natural defenses of the skin. We need an actual lesion there to start with. That comes from actual trauma or microtrauma, which is some of the terms that we've used for this disease process in the past, microtrauma, or we need to affect the integrity of that skin in some other way, which includes soaking it in water continuously and hampering the ability of that skin to be able to ward off and act as a physical barrier to bacteria.
Standing water is a risk factor for not only digital dermatitis or hairy heel wart, but foot rot as well, because the disease process has some similarities. We're affecting the ability of the skin to act as a physical barrier. You can certainly puncture that physical barrier with trauma, microtrauma, and that comes with certain bedding types usually, whether that's wood chips or deep bedded cornstalks or deep bedded really core straw. What we're trying to avoid is any poking or jabbing or trauma to the interdigital space or the heel of the foot that would allow, excuse the pun, a foothold for bacteria in that area where they can colonize and get things started.
When we look at this problem of digital dermatitis and we look at it from a systems approach, do I have a digital dermatitis problem on my feedlot? If the answer's yes, it's not just as simple as, "Well, I got it from here and that pen's infected and there's not a whole lot I can do about it because it's now on my farm." We have to look at what happened, especially because this is a slow-growing lesion and can be really easy to miss, especially in the early stages. We have to look quite a ways back to see, "Okay, where did this all start?"
If you've got issues with hairy heel warts or digital dermatitis, what happened potentially even three months ago, or, were we really doing a good job of checking feet on the way in? Because these lesions can be fairly small. The early lesions are quite small, really easy to miss. A lot of research shows that lameness is not a really good tool for evaluating whether or not you have this disease.
If you see lame cattle with severe lesions, that is absolutely the tip of the iceberg when we talk about this disease. You have had a problem for quite a while if you're seeing those cattle, and likely there's a big proportion of that yard or that pen or that group of cattle that have a problem and they've had a problem for a long time, but we just didn't find it. A lot of the research shows that these lesions take a while to grow, so they can go from the very early stages and get to a clinical level where we see impacts on the cattle, but it can take anywhere from 120 to 160 days.
If we're seeing lame cattle, likely we've had a long time where we could have hopefully seen something going on or done alley checks where we walk cattle through and we're really carefully looking at feet. Anytime we've got mud in the mix, which might come from weather itself or purposely from flooding the yard, it makes it even harder to see those lesions unless we're clean in feet. Once we enter the stage where we've got really chronic lesions that are quite big and we're looking at a lot of tissue loss, it's too late. We should have noticed this earlier, and that's the key.
It's slow-growing, it doesn't come out of nowhere, and we should have time to catch it or at least catch the majority of the cattle that have a problem before they get to a point where there's no return. We've gone on a tangent here and it's become less of a discussion about flooding yards or not flooding yards, and more of a digital dermatitis discussion, but I've been getting a lot of questions about this and I see a lot of these digital dermatitis issues connected to mud and standing water, and if we can prevent that by not purposely flooding our yards, I think there's a lot to discuss in that. The goal, when I'm talking about this stuff and talking about flooding yards because of the heat, is to look at it on a systems basis and look at what are the consequences of making that choice, the risks, the benefits. Can we truly weigh those if we're looking short term? I think the answer is no. We need to look long term at the systems approach to all this of what is really the benefit that we're getting out of flooding our yard and what is the cost or the potential costs down the road?
Even when I'm talking about digital dermatitis, all the way out to three, four, five months later when we're talking about one disease. We haven't even discussed all the implications that come with standing water in the yard for production and the effects of mud on production, drinking out of that water and risking especially certain ages of calves to coccidiosis and the transfer of that disease and ending up with production losses there. There's a lot more to discuss with this, but the point is that we need to look at it system-wide on a whole, what are the risks and the benefits of doing this?
For me, flooding the yard doesn't make sense in almost every case. There's so much we can do for heat mitigation or heat abatement that does not include making mud in your yard and causing these problems. What can you do? Well, if you're going to put water on cattle, you have to make sure you soak them. Just misting them or getting their hair wet is not going to cut it. You can put water on cattle, you're going to have some issues with mud, but hopefully, you are using water to a point where you're soaking the cattle but you're not creating a giant pond in your yard where they're continually soaking their feet in standing water.
You're not creating massive amounts of mud. It can dry out fairly quickly, all of that. We need to soak the cattle if you're going to do that, they need to be dripping wet. They need to be dripping from their belly, soaked all the way to the skin. Otherwise, you're causing more of a problem than you're helping. You're making those cattle hotter by creating another insulating barrier in the water. There is no evaporative effect if it doesn't hit the skin. You can't put water on cattle. Better than putting water on cattle, in my opinion, is putting water in cattle. Water is huge. Anytime you can add extra water to the pen when it's hot is a huge benefit.
If you've got stock tanks or something else that you can fill up once or twice a day just to add that little bit of extra water to that pen, it's 100% worth it every single time. The more water for those cattle to drink, the better. Shade is another big thing. Shade is huge. Now, we've got to be careful with shade because we can create a mud problem and we can make heat somewhat dicey with cattle if we don't have enough shade, because they will bunch under that shade and create a mud puddle just from having too many cattle in one spot. We've got to hopefully evenly distribute the shade as much as possible, have enough so the cattle aren't bunching together and getting hotter by being super close together.
That's a big factor, but shade is always appreciated. Fly control is one we don't think about enough in my opinion, especially in feed yards. Sometimes feed yards are around other operations, whether that's cow, calf or whatever else anybody has going on. If we've got wet organic material around, that is the perfect situation for stable flies. Stable flies cause the stomping. They bite, it hurts, cattle bunch up trying to get away from flies.
Fly control by keeping your premise really clean, potentially treating the cattle, potentially treating the premise itself. Those are all options that come back to heat abatement because they keep cattle from bunching up and getting hotter. Fly control is on the list for that as well. One thing we see in a lot of feed yards is mounding as well. If you can create mounds with enough space, cattle can get up and they can get more wind and a lot of times, just see with cattle when they're hot, they stand up. That is built into them. They want to be standing when they're hot. The goal being to get more airflow around their body and hopefully transfer some of that heat off them.
Wind is a big factor in that, so if you're not going to mechanically ventilate your feed yard, then mounding is a great option to make sure that we can get as much air across those cattle as possible with wind. Get them up a little higher, give them the opportunity to choose where to lay on that mound where they feel most comfortable and cool down. Those are all options, in my opinion, I would absolutely work on before I ever consider flooding my yard, because of all the reasons we talked about and we use digital dermatitis or hairy heel wart as a example for why I don't like flooding my yard.
There's a lot of downstream implications in the system from that one decision. Now, before we wrap up, I want to leave you with a thought. Now, people always say, all right, it's always the same pen that breaks. I think that pen is infected when it comes to digital dermatitis and that pen has the bugs. That might be the case, but one thing I want to think about or I want you to think about is, is that pen truly infected with the bug or are the conditions in that pen just conducive to creating this problem? Does that pen differ in any way from the other pens, or does your feedlot have all the risk factors that are associated with digital dermatitis or hairy heel wart?
That's why you continue to break, and it may or may not have anything to do with the bug itself being on your farm. Maybe the conditions are just perfect or the conditions of your source are perfect and then you exacerbate the issue, and that is why you always have a problem in either that pen or why your yard as a whole has a problem because the conditions are right. There certainly is some impact of having the bugs themselves, the bacteria there, certainly some of the key bacteria there that allow for this process to get kickstarted, but I do think there is a vast majority of the problem that sits with the conditions being right to create the problem.
Now, we jumped around a lot today. It was kind of a one-person potpourri of a lot of things. We took some tangents, we got soapbox issues, we got some things to consider. I'm done talking for today. I think that's plenty for everyone to think about. I think that's plenty of me talking and you hopefully still listening to me. If you have comments, questions, scathing rebuttals, which I definitely welcome, anything you guys want to say, anything you guys want to send in, I will happily discuss it with you. Please send that to themoosroom@umn.edu. That's T-H-E-M-O-O-S-R-O-O-M@umn.edu. Find us on Twitter @UMNmoosroom and @UMNFarmSafety. Find Bradley on Instagram @umnwcrocdairy. Check out our website https://extension.umn.edu. Thank you everybody for listening. We will catch you next week. Bye.
[00:17:51] [END OF AUDIO]


Episode 182 - Flooding feed yards and hairy heel wart (digital dermatitis) - UMN Extension's The Moos Room
Broadcast by