2025 Toxin Outlook with Dr. Marcus Kehrli

In this episode of AK Podcasts, Mike Donaldson engages with Dr. Marcus Kehrli, who shares his extensive background in veterinary medicine and animal agriculture. The discussion focuses on the increasing prevalence of mycotoxins in livestock feed, their impact on animal health, and strategies for prevention and management. Dr. Kehrli emphasizes the importance of understanding the signs of mycotoxin exposure, the need for testing feedstuffs, and the role of proper agricultural practices in mitigating risks. The conversation highlights the complexity of mycotoxin issues and the necessity for ongoing research and awareness in the field.

Dr. Kehrli references an article by Cathryn A Bandyke:

 | https://www.sciencedirect.com/science/article/pii/S2590286524001204?via%3Dihub

🎙️ AK Podcast Insights
🔍 Exploring the latest in livestock nutrition, science and beyond with the best and the brightest in the business.  Brought to you by Agri-King, an animal nutrition company based in Fulton, Illinois.

💬 Follow us for more!
📸 Instagram and facebook | X | 💼 LinkedIn | 🌐 agriking.com/

📧 Have questions or suggestions? Contact us at podcast@agriking.com.

Transcript

Chris Radke (01:53)
Welcome to AK Podcasts where we discuss science and nutrition with the best in the brides and the business. I'm your host, Chris Radke, part of the Sales Department here at Agri-King. And with me today is the Director of Field Services and a member of the Sales Management Team, Mr. Mike Donaldson. Mike, how you doing, buddy?

Mike Donaldson (02:07)
Outstanding, Chris. Having a good November so far.

Chris Radke (02:11)
⁓ yeah, yeah, yeah. I think November with Thanksgiving. November, Thanksgiving is probably my favorite holiday. I'm pretty excited about that. I love it. Love it. Love it. Yeah. And it's not too cold yet. So my kids can go outside and, you know, do things. So we're doing good. Good. Hey, Mike, what are we talking about today and who's with us?

Mike Donaldson (02:21)
Wonderful.

Well, Chris, today we're joined by Dr. Marcus Kehrli Marcus is a member of the board of directors at Agri-King, but something he values even more than that is that he is now a member of the exclusive two-time podcast guest club. So that'll be on the wall someday right by the diplomas. ⁓ In case you didn't catch Marcus's first podcast earlier this year on avian influenza,

I strongly suggest you go back through our archives and give that a look and a listen. Marcus grew up on a diversified farm in Iowa, and after that, his life went in many fascinating directions. So varied, I'm going to ask Dr. Marcus Kehrli to give his own background in case this is your first introduction to the man. Dr. Marcus Kehrli, thank you for joining us today, and please tell us about your career in the ag livestock industry.

Marcus Kehrli (03:22)
Well, thank you, Mike and Chris for helping get this podcast kicked off. And I'm coming to you from balmy, central Iowa in mid November. It's going to be in the 70 degree range today. So I'm not kidding. It's Balmy and we like it. We've got the grill ready to fire up this afternoon. So as you said, Mike, I grew up on an old fashioned livestock farm where we had various livestock and crop farming with my parents and grandparents.

Mike Donaldson (03:39)
You

Marcus Kehrli (03:50)
We had a small herd of dairy cows, a few beef steers every year. We had a small feral to finish swine herd, a flock of laying hens, a flock of sheep, some ducks, some geese, and a turkey that never seemed to survive the end of the month of November every year. So not sure what happened there. I was active in FFA and 4-H. I showed dairy cattle and raised hogs for projects. And I always have had an interest in science and medicine.

Obviously it began in high school, if not before, with the FFA. And I actually conducted a couple of research projects back then that included evaluating the benefits of growing high lysine corn that we used to finish some pigs that were on the project. then, in another project, collaborated with our local veterinarian to experiment on how we might synchronize the ewes in our sheep flock ⁓ to better manage the lambing season when we were breeding them.

That was a miserable failure. ⁓ But the lysine corn project was a lot of fun and it actually had some very interesting results. I then went on to attend Iowa State University where I earned several degrees, one in dairy science, one in bacteriology before I matriculated into the College of Veterinary Medicine to get my DVM degree. Just before graduating from vet school, Mike, I was presented with a very unique opportunity.

to explore a career in mastitis research and dairy cattle at the USDA's National Animal Disease Center in Ames. I knew nothing about that place and went out and as it turned out, I had a job interview and that ⁓ ended up changing my trajectory of where I went. So after completing my degree, I started out at the National Animal Disease Center working full time. And at the same time, I ⁓ earned a PhD in immunobiology.

My research focused on immune dysfunction of transition cows, which was a topic of particular interest to me, and as well as general inflammation and genetic differences in immune health of dairy cows. So I published on a wide range of dairy cattle immunology topics and genetics of trying in the, in the context of trying to improve the transition cows overall health. After over 16 years of research at the National Ambulance Disease Center,

I went on to join the pharmaceutical industry for five years where I conducted some research again with dairy cows, but also with beef and swine in search of novel therapies or preventatives for infectious and metabolic diseases. Five years of that, and I returned with an opportunity at the National Animal Disease Center in 2003 as the research leader of the Virus and Prion Diseases of Livestock Unit.

And over the next 10 years, ⁓ I had the privilege to lead a very extremely talented and highly productive team of scientists who led research on several emerging diseases of livestock, including mad cow disease or bovine spongiform, escephalopathy. And there will be a quiz at the end of the podcast on how to spell that. Chronic wasting disease and deer and other pre-aud diseases, well as numerous swine and bovine viral diseases such as.

Mike Donaldson (06:58)
Yeah.

Marcus Kehrli (07:07)
things that were introduced into the United States over that period like porcine circovirus type 2, high path PERS virus, which was not fortunately introduced in the US, but we wanted to be ready to deal with that. The pandemic of 2009, which was an H1N1 virus, coronavirus that entered the United States from China called porcine epidemic diarrhea virus, which killed off 10% of the hogs that year, or the baby pigs.

Seneca virus A, which is a look-alike virus with things that we don't have in this country, and hobie-like pest viruses in cattle. So that was a very challenging period. And after that 10-year period, I became the director at the Disease Center. And as I mentioned, it's the largest animal health research and bio-containment facility in the United States that works on domestic and transboundary diseases of livestock and wildlife. It's also one the largest such facilities in the world.

with the very unique ⁓ biocontainment capabilities with some of the wildlife we work with. Following my retirement at the end of 2020, I was asked by Clark Marcus Kehrli to join the Agri-King Board of Directors, and I've had the pleasure of serving on the board since July of 2021. That brings us to today,

Mike Donaldson (08:21)
Thank you, Marcus. I'm very thankful for two things. First is we can get someone as intelligent as you to be a guest on the program. I won't live long enough to have that number of experiences. And the second is, as the host of the podcast, I don't have to take the spelling test. I just get to ⁓ mentor the spelling test. So that's good news for me. The thing we wanted to talk with Marcus about today.

is the challenge toxins are presenting to animal agriculture. We're hearing from our field nutritionists at Agri-King, as well as the industry at large, that this could be a very, very big challenge this year, toxins are gonna not be good. ⁓ To start us off, what does the term toxin really mean? What's that speaking to? Where do they come from?

and what conditions make them more likely to be a problem in a giving growing season.

Marcus Kehrli (09:16)
Well, Mike, that's ⁓ a very broad, encompassing question, but technically speaking, toxins are just naturally occurring poisons. In other words, you can think of it as something that's naturally made by living things like bacteria, fungi, plants, or animals. It's nature's way of an organism defending itself or attacking another living organism or cell. And obviously toxins can make us sick if we come into contact with them through breathing, eating, or even skin contact.

depending on the toxin. Today, we're going to focus on mycotoxins, are chemically diverse metabolites that various fungi can produce either as a waste product in their metabolism or that they have evolved to use these mycotoxins to better compete in their environment for nutrients. There are over a hundred thousand species of known fungi. That fungus is singular, fungi is plural, but only a couple dozen of these fungi

are actually responsible for producing the vast majority of mycotoxins that affect livestock agriculture. When these fungi grow on our food, feed or crops under the right conditions, which require moisture, oxygen, stress on the plant sometimes, they may end up producing these mycotoxins. So they're not essential for the fungus to live. So they're considered to be secondary metabolites, but they do give the fungus an ecological or competitive advantage.

And ⁓ that will either help them deter insects or suppress competing microbes or even just help them colonize a plant. So Mike, I have a article that hopefully you can send out when this is over with or the link to it. It's a freely available article that's been published and it's a review on mycotoxins in ruminant livestock production. And the author, Katherine Bandic, ⁓ I believe did a very nice job.

of putting into concise terms and it will allow our Agri-King employees and nutrition consultants to ⁓ be able to refer back to something because I don't expect everyone to ⁓ memorize everything we're going to go over to today and put it into the permanent memory banks. But you can refer back to things in this ⁓ because our nutrition consultants really help our clients mitigate some of the risks with some of our products. So Mike, after the podcast.

I'll make sure you have the citation and the URL for folks to ⁓ download this and it was just published last year so it's relatively current.

Mike Donaldson (11:53)
So what are the, in layman's terms, I'm a dairyman, feedlot, I have livestock. What are some of the common signs I might be seeing in my animals that could be caused by toxins?

Marcus Kehrli (12:12)
Well, that's a challenge, Mike, even for veterinarians, because as I mentioned, ⁓ they have wide ranging effects. They affect a lot of different livestock species. It varies by age of the animals, sometimes even the gender, the sex of them, their reproductive status, whether they're pregnant or not, and the exposure level or duration of exposure. So ⁓ that all affects what we might see. And so you can...

find things from sudden death ⁓ to clearly the animals being ⁓ abnormal and displaying being off feed or reproductive issues. ⁓ You can see them be poorly performing as far as their production status and milk. But sometimes these things are so subclinical that they may be present, but they're hard for people to detect.

But this whole field of research is relatively new because modern, what we call mycotoxicology started in the aftermath of a veterinary crisis in England in 1962, when there were over a hundred thousand turkey poults that died. And back then they called it a turkey X disease in veterinary medicine and research. If, if we have a new disease, we often call it mystery disease or disease X. Well, later on, it was found that these turkey poults were being fed.


Marcus Kehrli (13:39)
feed stuffs that were contaminated with a peanut meal that had secondary aflatoxin in it. And this was the first discovery that alerted veterinarians, nutritionists, and animal scientists the possibility of potentially other risky fungal metabolites in a lot of our livestock and poultry feed. So the other thing I'd like to point out, it's extremely difficult to do controlled experiments with mycotoxins because we just can't

go out and make them chemically like the fungus does. And so that makes it difficult for people to do the studies that need to be done. But these mycotoxins can make them sick in many different ways. Examples, aflatoxins will damage the liver. You'll see slow growth rates. They cause immune suppression, all of which these can eventually lead to death. Aflatoxin is a cancer-causing agent. And in humans,

And that's why we closely monitored in milk and turkey poults are extremely susceptible to it causing sudden death. Layers could see a negative effects on egg production. Horses can show everything from colic, liver damage, neurological issues. ⁓ so it, it affects the liver, wide range of problems. Another mycotoxin called vomitoxin. It's got big long chemical name. Obviously the voma.


Mike Donaldson (15:02)
You

Marcus Kehrli (15:03)
It causes animals to vomit, particularly pigs, and they'll stop eating. We also see this in turkey poults. So you see that reductions in feed intake, diarrhea, immune suppression, reduced performance, whatever that might be with your animal species. Zearalenone, it behaves like an estrogen. It'll mess up reproduction. You'll see swollen genitals. You'll see mammary develop in barrows and steers. I've actually seen pictures ⁓

from veterinarians in the field that had a feedlot steer show up that were dripping milk. Obviously they had not given birth and ⁓ there was no reason for them to be lactating, but they were. ⁓ So a fumonisins ⁓ actually did some research on them back in the eighties, late eighties. They can kill horses by damaging their brains. They can cause pulmonary edema in pigs, which is a swelling of the lungs in general.

They cause liver and kidney damage, cause immune suppression and poor performance depending on their exposure levels. And so all these can, you all the major organs can be affected by these various mycotoxins. I'm not going to go through the entire list because it's one of these things that you have to take on a case by case basis. In general, young or pregnant animals get hit the hardest by these mycotoxins. And to keep animals safe, we really have to focus on

good crop management, proper storage, and then testing your feed stuffs if the animals get sick or just in a preventative mode. If you know you potentially have problems to be ahead of the game and do testing before you incorporate that new feed each season into your feed stuffs for the animals. And it's always important to call your veterinarian if you think you've got a problem to prevent even bigger losses occurring.

Mike Donaldson (16:55)
It seems to me, Marcus, that mycotoxin problems in livestock have become worse and more common in recent years. sometimes seems to me to, I think sometimes farmers think that this ⁓ is a bad nutritionist excuse, that well, things aren't working. Well, you must have toxins. Well, maybe you're not a very good nutritionist. But when we test and we look,


Mike Donaldson (17:23)
It just seems like this problem's getting worse. Is that true? And if it's true, are we more aware of it? What's causing it? What brings us to late 2025 and the situations we're dealing with?

Marcus Kehrli (17:39)
Mike, that is a complex pair of questions you've just posed. In my experience, the short answers to your questions are yes and yes. Yes, I believe it's true, mycotoxins are problems that are becoming worse and more prevalent. And I'll explain some of my reasoning here in a moment on that. But it's also true that with our advancements in science, we're becoming better at detecting and diagnosing and being more aware of what is out there. Obviously in 1962, those turkey bolts, we weren't thinking of mycotoxins and research into the area advanced our understanding of what was actually happening there. And this gets repeated as we find more and more problems as time goes on. So let me start by taking a short step back here and present a little bigger picture on ⁓ mycotoxins. On toxins.

Mike Donaldson (18:29)
Mm-hmm.

Marcus Kehrli (18:30)
I'm going to give this example, Mike, because I think it'll drive home a point later in this podcast as we focus on mycotoxins or preventing them in silage. So in the evolution of microbial life on our planet, molecular oxygen was actually the first biological toxin that had a global impact. And what do I mean by that? Well, this is the oxygen that we breathe today, but it wasn't in our atmosphere 3 billion years ago on this planet. And what happened was there was an evolution of microbes ⁓ in that what we call anaerobic or lack of oxygen biosphere. ⁓ And as they evolved, they developed the ability to photosynthesis ⁓ to release molecular oxygen. Well, it turns out that all the anaerobic bugs back then, they lacked the defenses against oxygen that we have around today. And those ⁓ organisms began to die off and the  oxygen loving organisms, they began to take off. So about two and a half billion years ago, this accumulation of oxygen caused a widespread microbial die off and reshaped life by favoring oxygen tolerant organisms. And I'm talking about molecular oxygen. So in simple terms, life's first forms were oxygen hating microbes, know, a world that had no free molecular oxygen in the air like we have today. And then some bacteria began pumping it out.

Mike Donaldson (19:54)
Mm-hmm.

Marcus Kehrli (19:57)
So today there are hundreds of thousands of distinct toxins that we know about, nature probably actually produces even more, maybe millions. So the short answer to your second question is yes, this is the longer version. We are continuing to become more aware of the various toxins that affect living organisms, which include all of the livestock and poultry that we help feed. So your first question, are these toxin problems in livestock becoming worse and more common in recent years?

Mike Donaldson (20:10)
He

Marcus Kehrli (20:26)
It appears the answer to maybe a qualified yes on that. And when you look at all of our data measuring mycotoxins and feed stuffs, I like to follow one of the ⁓ publications on this topic. And one of their big findings is that the co-occurrence or presence of two or more mycotoxins over the past decade in feed ⁓ has been on an upward trend. So detecting two or more mycotoxins in a single sample of corn rose from about 36 to 50 % of the samples 10 years ago or so to over three fourths of the corn samples the last two years had multiple mycotoxins in the corn. So the 2025 corn crop remains to be determined this year, but the weather patterns throughout the corn belt certainly do predict another year for producers to be doing everything they can to monitor for and minimize the impact of multiple mycotoxins in their feedstuffs.

So why is this happening? Well, the cause of the apparent increased mycotoxin issue over time has actually been under study. And there is a former USDA scientist by the name of Dr. Robert Kremer. And he studied the impact of long-term usage of an herbicide. And he focused on glyphosate because of its dominance in weed control in corn and soybeans. He looked at the impacts of glyphosate on soil biology, the ecosystem of that soil.

and the biodiversity of the microbes in that soil. And his research drew from very long-term field studies, as well as greenhouse and laboratory studies. So key findings of his research were that repeated long-term glyphosate usage was actually associated with a two to five-fold increase in certain fungi called fusariums and various species of them that colonize on herbicide-resistant soybean and corn roots. And along with that,

came a decrease in favorable bacteria in that same ⁓ microbiome. And there are research groups that went on to try to verify, and sometimes they found no effects of ⁓ glyphosate. But there are also other groups that had some similar findings to Dr. Kremer. The problem is that each of these three major research groups use different experimental methods. So.

I think one of the keys with Dr. Kremer's studies, they were the most long-term in design and involved actual field studies, which to me is quite meaningful. Unfortunately, Dr. Kremer is no longer doing research. He retired a few years ago and he's no longer living. But I did have the privilege of hearing his presentation that he gave ⁓ in September of 2019 on the tracking the effects of glyphosate on soil biological processes in the microbial communities. I think the summary of his research

Mike Donaldson (23:19)
Hmm.

Marcus Kehrli (23:21)
He was a big proponent of integrated weed management and not relying on a monoculture of herbicide usage with the goal of reversing that dominance of new fungi that he found to increase over time.

Mike Donaldson (23:34)
Hmm, that's interesting and that's certainly, I I can think back over in my lifetime when Roundup was brand new, I'm sorry, glyphosate, whatever. But that's certainly something that I can see an increased use of. ⁓ I never thought that was a big aspect of this. What crops are most likely to give us a high level of toxins that we have to deal with?

Marcus Kehrli (24:02)
Yeah, Mike, many crops can actually be affected, especially those that we use in livestock feed. But some are a little more prone and I'll just touch on a few of them and I'll expand a little bit on corn because it's highly susceptible to wide range of fungi that are capable of producing mycotoxins. And that's primarily due to corn's high starch content. And, you know, that's a nutrient that the fungi can actually utilize quite effectively.

And corn is also frequently exposed to warm, humid conditions during the growing season and or in storage. So the exposure to the fungi can actually begin in a narrow zone right around the roots of the corn plant. It's a tiny zone, maybe one to five millimeters away from the outside of the root. So very narrow. But this is a hot spot, if you will, of microbial activity that's influenced by things that get released by the roots called exudates or secretions.

And there's a lot of micro groups in that that little tiny zone. It's called the rhizosphere. That will to also be on the exam. But it's highly enriched in bacteria and fungi. And there's interactions there that the microbes work together with the root to actually increase the ability of the root to absorb nutrients out of the soil. But the beneficial fungi help the plant by competing against pathogens for the plant.

⁓ but it's a teamwork of all these microbes with the root plants, plant roots, should say, and, the beneficial organisms. ⁓ wheat and small grains can also suffer from this barley oats, rice, so forth, soybeans, sorghum or, ⁓ grain sorghum, milo silage of any of these products. ⁓ obviously silage is a fermented feed stuff and it's prone to mycotoxin.

ensiling process fails to lower the pH quickly, or if air, such as oxygen, as I mentioned earlier, infiltrates the storage during storage. ⁓ fungi need the oxygen. And so by lowering the available oxygen very rapidly through ⁓ proper ensiling or accelerating your ensiling process, products like what Agri-King has can go a long ways to helping reduce the amount of exposure.

Mike Donaldson (26:27)
So even something as simple as the close to 100 year trend where we've gone away from dry ear corn and dry hay and fed more high moisture feeds could be contributing to this increase in toxin issues.

Marcus Kehrli (26:45)
absolutely. Yeah. Organisms like moisture and they don't grow real well in the absence of water. So that ⁓ definitely is a big key.

Mike Donaldson (26:58)
Well, what can we do to limit the amount of toxins that we're bringing in from the field on these different crops?

Marcus Kehrli (27:05)
Well, I think there's actually a lot of things that we can do, Mike. We'll find variable benefit from some of them, but certainly ⁓ minimizing contamination on the crop itself by the ⁓ fungal organisms will be a part of what I'll point out here. But preventing the fungal infection certainly ⁓ starts in the field ⁓ with reducing plant stress and exposure to their fungal pathogens. So ⁓ obviously,

Continuous usage of the same herbicide over time can contribute to the population bloom, if you will, of some of these fungi that will produce mycotoxins. So rotating crops is a big factor there. So you don't have a year after year use of the same herbicides. ⁓ You can also select resistant varieties of your crops. I did a little Dr. Grock search, if you will, my favorite.

artificial intelligence engine, just to get a quantitative number of the number of corn hybrids. This last year, Mike, there were over 2000 commercial corn hybrids from over 70 different seed companies available. The vast majority, 80 to 90 % of these hybrids actually incorporate genetic resistance to keep fungal diseases of corn. Now, that's a standard selection criteria now in modern corn breeding programs.

and you can get this data out of various state extension services. But it's important to understand that the fungal diseases of the plant don't necessarily represent the fungi that might be on the plant that are brought in from the field that actually produce the mycotoxins either on the plant or after harvest. But those fungal diseases of corn, for example, can weaken the plant's resistance to the soil fungi that do produce the mycotoxins.

It's important to try to keep the plant as healthy as possible and mycotoxin resistant strain varieties of corn will help you ⁓ in terms of minimize the damage to the corn crop. Similarly, ⁓ there are options available for wheat and barley. Now, the other thing that people have done and some of Agri-King's nutrition consultants have actually given me this insight. They've had clients successfully use fungicides.

that are applied in furrow at planting time in corn. And what I mean by in furrow, it doesn't get put in with the seed, but it's put in within about a two inch zone of the seed. And one example was a product called Ziway. It is an in-furrow fungicide. And a few of our clients have achieved lower mycotoxin levels in their corn silage when doing side-by-side comparisons on their farms based on analyses at Agri-Kings and a lab.

conducted for mycotoxins. Now, when I went out and looked a little further, there are private trials and university field trials that have been looking at these types of approaches and their findings vary widely. And some of it comes down to the timing of a fungicide being applied, the disease pressure in the field, the historical disease pressure, because these things can carry over. But today there are a very large number of fungicides that are commercially available.

And this is just one example. I'm not here to endorse or to discredit it. It's just that the results do vary with application of timing, weather events, disease pressure. And we've certainly seen a lot of fungal diseases move northward this last year for corn throughout the corn belt. And I've heard some pretty remarkable ⁓ observations of use of aerial application of fungicides.

Mike Donaldson (30:34)
Hmph.

Marcus Kehrli (30:57)
in minimizing the effects of ⁓ fungal infections of the corn on yield as much as a 50 bushel per acre difference being sprayed versus not. So ⁓ you can go on and spray corn in the field with these fungicides. I know people that do this. ⁓ I think many of them are put on with the use of drones. And I think the outcome is

variable based on the disease pressure in the area that the farmer is raising their crop. Additionally, ⁓ insect resistance in these varieties that we plant is important because it will ⁓ reduce the damage that might be done to the ear or the seed, which does create entry points for fungi that may actually produce mycotoxins as a contaminant.

So crop rotation, residue management, I mean a very diverse approach to managing your production of your feedstuffs is very important because if you rotate with non-host crops and avoid corn on corn or other small grains to lower the fungal carryover, that will go a long ways to minimizing the disease pressure on your crop. Bailing, deep tillage to get the residues down so that they don't have.

the capacity to help over winter the mold. So good agronomic practices to maintain your soil health. ⁓ If you're in an area where you irrigate, obviously you can minimize drought stress, but using tillage to bury the residues, ⁓ I think that's something that's coming back in vogue that we need to pay attention to from time to time. and last but not least, make sure before you begin your harvest, clean out your storage facilities thoroughly between batches so you...

to remove dust and residual materials from the previous filling of your silo, bunker, or bin. Now the other thing, ⁓ at harvest, we can do a few things. ⁓ Timing and techniques that you use to harvest are critical at limiting the mold and fungus exposure and growth. So getting your corn silage harvested at the right moisture for better compaction and fermentation, those are obviously things that good producers are able to do, and they know all the methods to do that.

⁓ I would always encourage people using the Silo-King products for both corn and hay. ⁓ It's formulated to protect and preserve many types of feedstuffs. And Agri-King Hay is certainly designed to help speed the curing process and limit heating and reduce spoilage, resulting in a higher quality hay. Another thing that maybe a lot of people don't think about, or if they do, they're thinking maybe in a different direction.

minimize the soil contact and fungal contamination of the silage and do this ⁓ by controlling the height of your chop. Some people have been raising the cutting bar, you know, for many years a lot of people cut it four to eight inches above the ground. People now realize that higher cuts, 12 to 18 inches as a minimum are useful for improving fiber digestibility and lowering nitrate levels of the silage which are actually higher in the lower part of the corn plant and

guess what, it also serves to reduce soil contamination that's more common on the lower stock. So that soil contamination has the soil fungal organisms. ⁓ Recent conversation I had with one of our Agri-King nutrition consultants that I have had the pleasure of meeting, Andrew Aarons. Andrew is unique. He owns and operates his own large dairy and also has a custom chopping business as well as being an Agri-King nutrition consultant.

Chris Radke (34:26)
you

Marcus Kehrli (32:50)
And talking with him, he said he likes to set his chopper to cut it 24 inches because otherwise it costs him more to chop that extra lower stock that's also higher in lignin, nitrates and soil contamination. If he cuts lower, then he has to pay extra to haul the lower digestible portion into the bunker or silo, which eventually results in a TMR that's got lower digestibility and lower feed value to the cow. Andrew further argues.

He would then have to pay again to haul that undigested material in the form of manure back out onto the field. And that common sense philosophy makes a whole lot of economic and nutrition sense to me. And it makes them very good health science by reducing the amount of fungal contamination. So just, just a little kernel of thought to share with people, no pun intended on the kernel of corn.

Ensiling, apply Silo-King during harvest to accelerate the fermentation process to drop that pH quickly and to create an anaerobic environment that helps inhibit the fungal growth. Like I said, oxygen is a toxin for fungus and you can't, I can't emphasize enough that Silo-King is far more than just a typical inoculant through years of research and developed by the Agri-King research lab team. They have made Silo-King

with a combination of three different strains of lactic acid producing bacteria that work in sequence of each other, along with an arsenal of 16 different enzymes that combine to play a role in accelerating the ensiling fermentation process and making the nutrients in that silage more readily available during ⁓ rumen digestion in the cow. So by more rapidly creating an anaerobic environment in the silage, this helps minimize

aerobic fungal growth that may contribute to mycotoxins in the silage. And Silo-King also contains potassium sorbate that helps preserve the silage against further mold and yeast growth. Finally, I think it's important that Silo-King has antioxidants that further aid in minimizing the development of an aerobic condition in the silage. So additional good ensiling practices, make sure you get it compacted right and sealed off to ensure an anaerobic silage pack.

and getting the proper uniform chopping length, packing density, using heavy equipment, sealing with plastic covers and oxygen barriers to exclude the air. You want a good balance between sufficient effective fiber length on the chopping length, but you also want good rumen and health and digestibility. So when I'm walking through a herd of cows, I like to see three out of every five cows that are laying down or standing comfortably in the lot to be chewing their cud.

This is a great indication of rumen health. So three out of five cows, you probably have good effective fiber in that ration. If it drops much below that, you need to start paying attention to whether the ration is too finely chopped or the feed bunk is not being managed properly. Inadequate cud chewing can lead to subacute ruminal acidosis and can also indicate cow discomfort issues. So herds with rumination collars or sensors will have a lot of extra data that you can look at.

And it'll give you a 24-7 picture, which is great, but I like walking the cows too, because it'll always give you an opportunity to see other things that might be happening in the pen. For grains, make sure you get them dried properly, and moisture control is essential. If you can, make sure you harvest them when it's cool enough, and you aerate the bin when it's cool at night. ⁓ And obviously keep hay stored as low moisture as you can get it there. So...

Those are kind of the keys to me of preventing it in your products that way.
 
Mike Donaldson (28:27)
When storing a forage, what can be done to keep those toxin numbers from increasing in storage?

Marcus Kehrli (38:36)
Using Silo King as a product is really best suited for your operation because it gets you off to a great start with that silage and it'll also make sure that you can keep the cover on it from being damaged by wildlife or the mechanical bull, which can sometimes ⁓ damage materials and I'm referring to the tractors and so forth. So make sure that all of that gets done properly.

Mike Donaldson (39:03)
Marcus, what are your recommendations when it comes to testing different feeds for toxins?

Marcus Kehrli (39:12)
It's best to just have a program of ongoing monitoring ⁓ and mitigation of the various steps that are in your feed program to make sure that you minimize the mycotoxin exposure and the effects of those on your animals. So sample and test your feed stuffs before you actually feed them to the animals.
 
Marcus Kehrli (39:32)
especially if mold is visible. But the mold can also be gone and not visible, but the mycotoxins can remain because they are very durable and they are not readily inactivated by virtually anything that we have available to us. So with Ruminants, I know the Agri-King Analab, they want to start with testing our TMRs or the partial mixer actions, the PMRs. And many of our producers already add flow agents that help with

These challenging feed sources, know, things that contain clay-based materials like betonite, yeast cell wall extracts, or aluminosilicates. These are effective for aflatoxins, but they vary for the other mycotoxins like flumonisins, and they're not quite as effective. One thing that I'll emphasize is that Agri-Kings AKMC is a flow agent for the further manufacture of feeds for all classes of dairy, beef, swine, and poultry.

So it helps livestock deal with these challenging feeds and it has various absorbent properties. It's got sodium bentonite, rice hulls, yeast extract, clay. It's got hydrated sodium calcium, aluminum silicate. It also contains proprietary formulated enzyme technologies that Agri-King has developed that help to improve fertility and performance when animals are being fed these challenging feeds.

And finally, AKMC also has antioxidants and vitamins and trace mineral fortification, which will help boost the overall health of the animals faced when eating these challenging feeds. So you can also, as a last resort, if you know you've got problems with some of your feed stuffs, dilute it, segregate these contaminated feeds by blending with clean sources to dilute them down below safe levels. But ideally,

It is really preferable to find clean alternatives because defining a safe level for me is extremely difficult, especially with the co-contamination or co-occurrence of multiple mycotoxins in the same feed stuff. So certainly discard your moldy portions and avoid feeding a multiply contaminated feeds together. If you feed mildly contaminated material to less sensitive animals, such as the wild deer in your area, just kidding, but you get my drift. ⁓

Boosting the immunity of your animals with the antioxidants like those found in AKMC may help. These methods can help ⁓ reduce the contamination risks and combined with all of our other programs such as using Silo-King. So it's difficult, nearly impossible to completely eliminate a mycotoxin exposure, but keeping it down to a level where animals performance and overall health is not affected will be very critical. And you should always contact

your local extension services for advice based in your area because your local climate and crop specifics will vary.

Mike Donaldson (42:34)
Marcus, you mentioned the possibility for more than one toxin in a feed. Is that common? you often see multiple toxins in a single feed?  

Marcus Kehrli (42:46)
Well, Mike, that's a great question. And I'm glad you asked because in preparation for today's podcast, I began with what I would say is a very biased view on the problems associated with the co-occurrence of mycotoxins ⁓ because of one, because of my past research expertise and experience with mycotoxins at NADC, where I worked for over 33 years. in the early 1990s, we published some research on the effects of fumonisins in corn.

And it was in corn screenings. Now, the argument was these corn screenings had 90 % of the nutrient value of US number two yellow corn. And so they were trying to feed it back to various animals. And some of the animals that was being fed to were horses. And ⁓ some of those horses had some very serious damage to their brains. They had head pressing. They would actually almost put their head up against the side of a barn and push ahead right through the board. ⁓ So they obviously had a bad headache.

And we didn't want that to be happening. We looked at this in some feeder calves and we fed it to them for as part of their diet, some of these corn screenings for 31 days. And what we found was that there was some pretty, pretty evident liver damage that the pathologist could see under a microscope, but we also could see elevated liver enzyme levels in serum. And with my background, we were looking at the immune system.

were able to detect some immune impairment and there was a negative effect on ⁓ the rate of growth in these feedlot calves. So that was a problem. Then much more recently, ⁓ when I was working at USDA, we had problems with ⁓ some of our research animals for completely unrelated projects where we eventually figured out that we had problems with vomitoxin and

in some of our feed that we were giving to young, very healthy, ⁓ baby pigs that we had purchased from what we consider to be very high health herds. And these pigs would be vomiting and have diarrhea within 24 hours of being switched over onto our feed. We also had a situation with turkey poults that were dying off within a couple of days of age. And this was all from commercially purchased feeds that we later discovered were contaminated with multiple mycotoxins. So.

Given my background for years, I've been following these published reports on this topic. One of the longest running data reports, which has been out, ⁓ is put out by a company that's now DSM-Firmenich. And each year they come out with this report. And in February of this year, they reported that in seven of the past nine years, corn harvest, over half of the corn samples they tested had two or more mycotoxins present. Now,

The two most recent years, that percentage was 78 and 76% of US corn harvested in 2023 and 2024 respectively. They had a co-occurrence of two or more mycotoxins. So importantly for today's audience, ⁓ Agri-King has been taking an extensive look at this. And as you know, Mike, they expanded their laboratory capabilities a couple of years ago with the addition of some brand new ⁓ state-of-the-art equipment.

And Agri-King's own analab has tested 1,948 TMR or PMR samples from the 2024 harvest season. And they found detectable levels of two or more mycotoxins in almost 99% of the samples tested across all of Agri-King. So that includes Agri-King Limited. So the most common mycotoxins detected by analab have been xerallinone, 98%, almost 99%.

Mike Donaldson (46:30)
Wow. ⁓

Marcus Kehrli (46:40)
of the samples tested, vomitoxin in 95% and fumonisins in 89% of the samples. So these are the same top three mycotoxins detected in the DSM-Firmenich survey. So obviously it's overlapping their findings, very similar results on this co-occurrence. You can figure out that if you got 99% of them with zearalenone, 95% with vomitoxin and 89 % with fumonisins, that doesn't leave many that are

free of anything. So there is a bit of a drop off for the next most common mycotoxins that Analab detected which was T2 toxins but they also did pick up aflatoxin in some of the samples about 8 % and ochratoxin in 6%. So I may be biased if there's anything you want to take home from today's podcast it ought to go along these lines.

Averaging those, I'd say over 75% of the feedstuffs tested for mycotoxins in the last year or two have two or more mycotoxins present. The weather patterns this past crop year in the United States predict this year's feedstuffs will be similarly affected across the corn belt. Mycotoxins can have additive or even synergistic damaging effects on tissues and organs of livestock and poultry that will affect their health and performance.

Even low levels of mycotoxins can cause damage to the liver, immune system, and other tissues, thus negatively affecting metabolism, health, and performance. So given the rate of co-occurrence of different mycotoxins in feedstuffs, in my view, no levels of mycotoxin contamination should be considered safe when they have these additive or synergistic effects, because much of the research that's been published on what's considered safe is for a single mycotoxin.

We know we have more than one present in the vast majority of our feedstuffs. So we should do all we can to minimize the negative impact of mycotoxins on health and performance because performance may be the main thing that people are seeing if it's at a low level exposure over time. But we want to maximize the health and profitability of our clients' herds and flocks.

Mike Donaldson (48:54)
There's been a lot of attention given lately to how the effects of something like heat stress can have longer term negative effects on an animal even to following generations. ⁓ Do toxins enter into this type of a concern?

Marcus Kehrli (49:13)
Mike, that's a question that I have to be honest and say I don't have an answer with regards to the effects of mycotoxins on heat stress. ⁓ but I cannot imagine that they're good. ⁓ I think we should have a future podcast that focuses on this topic of heat stress effects, because as you know, there's some, ⁓ research that's come out that heat stress and late gestation has long lasting effects on the next generation of daughters. And that's heard in fact, it affects at least two generations. So.

This body of published and extremely fascinating research about what they call epigenetic effects on late gestation heat stress, it really deserves a more in-depth discussion on its own. So we certainly have Agri-King products that help cause this heat stress that could certainly play a valuable role for producers concerned about this during the summer season.

Mike Donaldson (50:11)
Well, you've laid out what to me, Marcus, is a very frightening scenario of what toxins can be doing in livestock. Once we've got them, once we know we have them, are there things we can do nutritionally to try to minimize those effects?

Marcus Kehrli (50:30)
Well, I hope there are, and I think we've summarized many of them already, Mike, but I'm going to put this on a focus on transition cows. As you know, Mike, I spent most of my career studying inflammation and immune suppression in transition dairy cows. That transition cow has many, many challenges that she must overcome. Mother Nature appears to have designed the pregnant mammals to experience immune suppression around the time of birth.

And we can detect that this, this immune suppression begins as early as 10 to 12 days before calving. And depending on the cow, the individual cow, her immune system will bottom out in the first seven to 10 days after calving and then slowly recover over a period of days to weeks, depending on the cow and the environment that she's in. So this immune suppression leads to what I consider to be dysregulation of the entire immune system. Because when that transition cow experiences an infectious disease.

like mastitis or metritis, diarrhea or respiratory disease, it's going to be more severe in that transition postpartum period than it will be in later lactation. So this same transition cow is also undergoing huge metabolic changes associated with a sudden demand for energy protein and calcium to go into that milk. And with that sudden change, she's also supporting the growth of the fetus at the end of pregnancy. And so with that sudden onset of lactation,

Those demands put tremendous stress on her liver and she must manage those energy needs with mobilization of long chain fatty acids from her fat stores and the liver attempts to prevent the development of fatty liver and ketosis. Well, that same liver is trying to detoxify mycotoxins that she may be consuming in a ration. So I believe we need to do everything we can to properly manage the transition cows metabolic needs and it

at the same time help her mitigate the mycotoxins that she's likely consuming in her diet. And a product like AKMC, which may aid in reducing the demands on her liver to detoxify the mycotoxins can only help the transition cow get started on her next lactation. As you know, any disease hit in that postpartum cow can have a permanent, and most likely will always have a permanent impact on the entire lactation curve for that lactation.

that she will not reach her full production potential. So avoiding diseases by maintaining her through that transition period at an optimal level is extremely important. AKMC, Trilution, Bovine Replete and so forth. These can help support her metabolism and immune system during the transition period to get her off the best possible start of her lactation. Cause it does set the tone for the rest of the lactation. You know, I really think of these high producing dairy cows.

as metabolic Olympians, you know, the very best. And given that they are genetically endowed with very high production capability, the dry and transition periods are when we need to train their digestive and lactational metabolic systems to perform at an Olympic pace.

Mike Donaldson (53:44)
Dr. Marcus Kehrli, do you think there's anything that we'll be able to do going forward to maybe decrease the problem that mycotoxins present?

Marcus Kehrli (53:56 )
Well, ⁓ I've had kind of maybe a little bit of a negative tone with the problem of these mycotoxins, but I don't think it's hopeless. I think we have some things that we can do, but it's going to be an uphill battle. To start with, I do believe we need to focus on modifying our agronomic practices that we use for crop production. I do believe we should fully embrace the research that Dr. Kremer and others have done.

on this topic that shows we have altered the microbial community in the rhizosphere of the roots of our crops. ⁓ I think that altering those beneficial bacteria and fungi in that growth region in the soil for the plant is likely contributing to the increased exposure of plants to undesirable fungi that do have the ability to produce mycotoxins. ⁓

Anything that we can do to minimize stress on our plants and animals that consume those plants, we need to do. We should validate their recommendations of this diversified integrated weed management, includes crop rotation, cover crops, rotational use of unique herbicides, mechanical weed control, reducing crop residues between the growing seasons. All these are things that can help us mitigate the amount of mycotoxin producing fungi in the soil.

So much more research is needed in this area of agronomy because in my view, it's our only means of knowing whether or not our methods will be effective in lowering the occurrence of mycotoxins in feedstuffs. On the animal side, we need to continue investing in research to reveal additional methods to mitigate the mycotoxins that do reach the feed bunk. And ideally, maybe we can identify methods to detoxify mycotoxins before they're fed to our animals. Only then will we have provided some

you know, very valuable tools to help manage this problem.

Mike Donaldson (55:52)
Marcus, I really appreciate you being on the podcast today. This has got to be one that people are going to need to go back and re-listen to and grab a piece here and think on it a little bit. And I appreciate you taking some very complicated things and making them understandable for us. Any wrap up kind of observations or comments you've got on the topic?

Marcus Kehrli (56:17)
Well, Mike, we'll send out the link for that review article and make that available to everybody. I'm also working on what I'm going to call a short ⁓ abbreviated handout that our nutrition consultants, hopefully it would be something that they could carry around in their pickup and ⁓ have as a resource to look back at these things because you can't be an expert on all this stuff and ⁓

Just having that as a backup resource, think it'll help people. once I get that finished up, we'll make sure that gets sent out to everybody or you can make that happen.

Mike Donaldson (56:58)
That's wonderful. Thank you again. So Chris out of the long list of things that you learned today What do you want to summarize and tell us that you picked up on?

Chris Radke (57:07)
I have no idea where to start. One of the things I'm fascinated with is Dr. Marcus is still researching and like still finding new developments and he's willing to expose that with us, I guess, kind of walk us through his trial. we'll put that article at the bottom, I think, of our podcast. So that should be there for whenever you happen to listen to this. It should be a link there as long as that article is still up. My big takeaway is that that statistic, he said that over half of feedstuffs tested for mycotoxins have two or more mycotoxins present. I was like,

That's kind of flooring, I guess, and kind of frightening at same time. If you like what you heard, if you'd like to hear more, you can find us on any of the socials. Please leave us a review if you happen to listen to us on podcasts or however your ⁓ Apple or whatever you're looking for us. And you can find us at the bottom of our Agri-King website now. And if you have any questions or follow up thoughts for us or Dr. Kehrli please hit us up at podcast@agriking.com. All right, Mike, Dr. Kehrli, thank you so much for taking your time.

Mike Donaldson (58:07)
Thank you guys, appreciate it.

Marcus Kehrli (58:07)
You bet, have a great day.