68: Why Multiple Mycotoxins in the TMR Increase Dairy Herd Risk

Multiple mycotoxins in the TMR do not just add up. They multiply damage in dairy cows.

In this episode of Ruminate This, Scott Zehr and Vice President of Nutrition Dr. Larry Roth connect their previous episode discussions and explain why multiple mycotoxins in the TMR create a multiplying negative effect in dairy cows rather than a simple additive one.

They discuss how common toxins such as DON, fumonisin, T-2/HT-2, and zearalenone each remove a critical layer of biological protection. Even when individual toxin levels appear “safe,” combinations can lower the cow’s ability to defend herself, regulate intake, maintain rumen integrity, and support reproduction.

The episode explores high-risk toxin pairings, early warning signs such as inconsistent intake, erratic manure, milk production plateaus, and reproductive challenges, and why multiple low-level mycotoxins are often more dangerous than a single high-level exposure.

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Transcript

0:01

Hello everyone, welcome to Ruminate This with Agrarian Solutions. Join us as we explore ruminant nutrition and the impact of mycotoxins. Here we challenge your curiosity and explore new industry insights and research to optimize your herd's health and performance. Our vice president of nutrition here at Agrarian Solutions. Over the past couple of months here in 2026, we have spent time doing more of a deep dive into Larry. I'm going to say the big four mycotoxins that we see in the U.S. Don, also known as vomitoxin, xerolanone, T2, HT2, and Femonicin. And so Larry, I want to thank you one because I felt like those episodes, even for me, were very informative. So hopefully the listener got something great out of those episodes and learned a little more about what these mycotoxins do on a biological level. But Larry, we get to see sample reports, you and I do, and other team members here at Agrarian from across the country daily almost, thousands of samples a year. And Larry, I tell you what, it's getting less and less common to see one mycotoxin show up on a sample. Just certain growing conditions, I'm going to say, weather patterns, whatever it is. This past week, or in the past two weeks, I should say, going back to the beginning of February 2026, the first 13 days in February of samples that came in in my region of the US, not a single sample came back with less than two toxins. Many of them had four. All four that we've discussed. One particular sample assay that comes back to mind was in the close-up pen of a dairy. So the close-up TMR sample. High xerolinone, high Don, T2, Femonicin. I've asked you this question before, Larry, but I'd like you to just kind of reiterate or frame it up for us to understand better. But what happens biologically to that cow when she's exposed to all four of these mycotoxins simultaneously? Wow, that's a great question, Scott. What happens when that cow is challenged by all four of our more common mycotoxins? Well, there is a rather than being additive, Scott, the effects coming together, think of it as being more multiplying each other. Because each particular mycotoxin strips away a layer of protection. So they just got to think of it as multiplying each other. We're destroying digestive tract integrity. So it's easier for more of the other mycotoxins to get into the blood system. Then we're slowly destroying the liver. We're changing hormone balance, we're taking down the immune system. And so each mycotoxin has, shall we say, a multiplying effect on the others. And that's what makes this kind of interesting is we can't say it's just a certain level of each one that causes issues. Because when we have multiple mycotoxins, the threshold level for the cow to defend herself is reduced more and more by each mycotoxin that comes into play. So beachheading referring to when we uh put all of our troops on the beach in Normandy to storm the front and concentrated everything in one area. Well, you know, if we had just one mycotoxin in the TMR, for instance, um, so you know, when if we just had one mycotoxin show up in the diet, it honestly it's almost like a win. Because if Don's going in there doing bad stuff in the room and causing some inflammation, the immune system is going to send all of its effort to that area, right? Or to take care of that thing. But now you have four different mycotoxins, each with a different attack mode or attack protocol. Yep. And you know, so that immune system's got to go in many different directions. Is that kind of how that would work? You bet. Yeah. Now we got four different mycotoxins that are attacking the immune system or the liver. I'm going to back up to, and I really like your analogy, the beachhead, the use of that term. Think of the beach head here as breaking through the castle wall. That's the dog. We're disrupting the rumining, we're disrupting the small intestine lining, so it's that much easier for everybody to get into the body. And now the immune system has to deal with multiple mycotoxins. Now the liver has to deal with multiple mycotoxins. So yeah, I kind of like that beachhead term. We just have to get that break in the digestive track lining, and then everybody comes ashore, if you will, and gets into the animal to cause their mischief. Yeah, and I think we've talked in the past about this, and it feels like oftentimes it becomes a almost like a chicken in the egg conversation. What's worse? One mycotoxin at a really high level, or three or four mycotoxins, even just two mycotoxins at a lower to moderate contamination risk. I'll let you expand on that. I'm gonna go ahead and vote for the multiple because again, each particular type of mycotoxin strips away a certain level of protection. Yeah, so I really do like thinking of the effects being multiplied rather than being additive. So I would vote for multiple mycotoxins at lower levels as being worse than a single mycotoxin at a higher level. Yeah, I think that makes a lot of sense. It just each one that's there, they they just attack a different way, so it creates more problems. So uh I want to think about some of these assays that I've seen come through, and I'll just kind of do a back and forth with you. What do we need to be concerned about when we see Don with fuminocin? Okay, Don and Fumonacin. Well, the Don is breaking through the castle wall, increasing gut permeability, and then you got fumonacin that has a liver effect, as well as taking down the immune system. So we've got gut permeability and inflammation taking place. Okay, how about fuminosin with xerolinone? Okay, similarly, we got fumonacin taking down the immune system, attacking the liver, and then we've got xerolidone disrupting hormones. Okay, how about don and T2 running together? Okay, a Don. Again, come back to our gut permeability is increased, and this can be rumen or small intestine, and then T2 just takes everything down. That's the finisher. When we talked about T2 recently, we were emphasizing HBS, hemorrhagic bowel syndrome. So we have increased gut permeability so that more bad guys get in, and now we're taking everything down to increase the HBS risk. Yeah. And then I'm gonna throw this one at you xerolinone with almost anything else that we that we test for. Because there's I think a unique thing about xeralinone being fat soluble that plays into this. Right, right. Yeah, well, again, xeralinone disrupts hormone balances, and all of the others they work either increasing gut permeability, taking down the liver as detoxifying abilities, taking down the immune system related to trying to reduce inflammation. So think of xeralinone and anything else as we're disrupting hormone balance and making it that much harder to protect the body and resolve the different issues. The key is that multiplying effect of multiple mycotoxins showing up in the feed. Yeah. You know, and I think some things that you know we see, I always say, okay, well, what do I need to look for? Right. And so I'm I'm thinking of inconsistent intakes with the with the Don, right? Or or erratic manure. Uh what are some other things we should probably think about? Okay. Milk production. Cows aren't increasing in milk production like they should, being flat to trending down, and then the reproductive success. Cows aren't getting pregnant and staying pregnant, either because alinone is messing up the hormone balance, or all of the other mycotoxins were showing up and causing inflammation issues that redirects nutrients to less profitable purposes, just trying to stay alive. You know, one of the I think things that we hear on a regular basis. And I certainly experienced it when I was on the dairy. Why do I just all of a sudden have random cows going off feed? What's causing this? And then you get the vet there, and they're like, I don't know. Probably ought to look maybe towards the mycotoxins as being causative. Absolutely. Again, the analogy I like to use, Scott, is if we were to go to a real nice buffet, and if one of us wasn't feeling well, that person's probably only gonna go up once or twice. Whereas if that person was healthy, man, they'd be going up time after time after time. So when cows don't like to eat, it's probably because they're not feeling well. And all of these mycotoxins can contribute to the cow feeling out of sorts and not eating like she should. And if the cow is eating less than what she should, we have fewer nutrients going in to take care of the immune system. The body's military. We have the cow not feeling well, not drinking like it ought to, it's more likely to get dehydrated and we lose our tight junctions. Tight junctions now become interstate highways for pathogens and other bad stuff in the digestive tract to get into the body. So, again, I I keep coming back to with multiple mycotoxins, the effects aren't additive, it's more of a multiplying effect. Yeah. You know, I want to just kind of think about some takeaways here. And we've all heard the term dirty feed before. And when I hear the term dirty feed, usually it's you know, it's it's it's related to either high mycotoxins or it's moldy or whatever. And you know, we talk an awful lot at agrarian about feed hygiene. And certainly I think mycotoxins fall into the conversation of feed hygiene. Uh, but Larry, expand on this point, if you would. I don't necessarily look at this point in my career to mycotoxins as being a feed defect or a feed hygiene issue per se, but maybe I'm starting to think of it more as a challenge to the biological system that the cow is. Your thoughts on that? Yeah, I really like that biological system. We can back up all the way to the soil, soil's biological system, the plant's biological system, the fermentation process is biological, and then the feed being utilized by the cow is a biological system, and the cow herself is a biological system. So you can see where if we start to have issues with soil health, relates to plant health, relates to mycotoxin occurrence, so it's also interrelated. And again, forgive me for repeating myself, Scott. It's not additive, it has a multiplying effect. Yeah. So, you know, let's think about maybe Larry. I'm gonna say traditionally, the way that perhaps we have always thought to mitigate the effects of mycotoxins in cattle, right? We had clay-based products or yeast cell wall fracture-based products. And you know, they're going back to the Cajal et al. research that we've discussed on this platform, there's some binding that takes place on certain mycotoxins. Zerolinone is one of those ones that, for instance, is bound at a higher percentage than say Don is, but it's still not a very high percentage. Right. But I guess the way I want to frame this question up to you is if I have multiple mycotoxins present and I were to feed an ingredient that helps mitigate one of those, how much benefit is that going to give me? Okay, great question. Well, I think the classic research on this area, Cahala et al. from the December of 22 Journal of Animal Science would suggest that, yeah, there are variations between the different mycotoxin mitigation products for their ability to tie up mycotoxins, just as there's variations in ability to tie up nutrients. So tell me the mycotoxins in question. Tell me about the different challenges that the animal is going through, and how the people are trying to manage the animal, and we come back to our biological systems, they're all interrelated, yeah, and it all starts with the soil. So I'm gonna ask you one more question here, and so if we're dealing with a biological system and we're trying to mitigate the the effects of mycotoxins within a biological system, how does DTX play into that as a biological approach? Okay, and what is DTX doing biologically to help that cow? Okay, what's the logic behind using DTX? Well, we theorize that DTX being a live bacteria is working at the small intestine level because of small size to take up residence in some of the intestinal cells. Doesn't have to be every cell, because there's something called quorum sensing, where the cells kind of communicate across each other, saying, hey, we've got something here. We need to elevate our ability to kick these mycotoxins out, just like other waste products or undesirable substances. We have these export proteins, and the export proteins seem to be activated by the mere presence of the cell wall deficient bacteria. So mycotoxin gets in, transport proteins finds them, seeks to kick the toxin or undesirable substance back out into the digestive tract to flush down the river. And again, we don't have to be in every single intestinal cell because there's communication that takes place across the intestinal cells. So it's really a neat biological system. The different animals, in our particular case, the one of greatest interest is the dairy cow, the high-production dairy cow has that ability to recognize these pathogens and decide to kick them out. So it's it's really neat, Scott, how all of this is integrated together. It is, and I think that's the the unique approach here, right? Is is that we're not treating the feed, we're not treating the mycotoxin, we're elevating the cow's ability to protect herself by helping the rumen, the gut, the liver, the immune system, and the endocrine system. That's right. Yep. And it all comes together, it's also integrated as that biological system. Yep. Well, I I really appreciate you doing these deep dives with me, and in particular today's episode, because we we do continue to see a lot of multiple mycotoxins, and I think sometimes we get hyper-focused on Don or we get hyper-focused on xroanone, and then if T2 and Femonacin show up that I'm gonna call it low contamination levels, right? We just kind of say, oh, well, those numbers look low on the on the assay, so we don't really have to worry about it. Well, come back to our multiplying effect. Each particular type of mycotoxin takes away one particular layer of protection. So again, that multiplying effect. Yep. Awesome. Well, thank you again, Dr. Roth, for jumping on with us today and bringing this series, if you would, home. And if you all have any questions you want to ask of us, you can always go to agrarian solutions.com and fill out the question form on the website. You can also email us directly, podcast at agrsol.com, and we can put you in touch with Dr. Roth or Caroline. We can make sure we answer any questions you might have in this space. My last takeaway, Larry, and I'll ask you for one as well. I'm gonna say sample, sample, sample. Test your forages regularly, test that TMR on a monthly basis. Know what is going into that cow. Absolutely. And Scott, I would just encourage people to sample their different feeds going into storage and then do the regular testing as we feed them out. Absolutely. All right. Oh, hey, everybody, we'll be talking to you again in a couple of weeks. Again, remember we air on the second and fourth Monday of every month. Have a great time. All right, thanks, Scott. Thank you for listening to Ruminate This with Agrarian Solutions. Look for our next episode in two weeks.