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Ep. 083: What We’ve Learned About Equine Nutrition and How It Can Help Your Horse

Co-host Katy Starr chats with guest expert Dr. Stephen Duren, PhD, MS, PAS about how we used to feed horses and how scientific research has changed the way we feed our horses.

Episode Notes

On this episode, co-host Katy Starr chats with guest expert Dr. Stephen Duren, PhD, MS, PAS about the history of equine nutrition, including:

  • The differences between horses used in war, agriculture, and transportation and how they were fed for those uses versus how they are fed now
  • How and why the industrial revolution put a halt to equine nutrition research
  • What has been the greatest advancement in equine nutrition research that we can apply to our modern horses

This episode takes us on a journey through time to learn just how observant horse owners were, even without the science, to determine what a horse might need to eat in their diet to handle their workloads.While horses provide more recreation and competitive opportunities for us now, they were crucial for survival for generations before us.

Have a topic idea or feedback to share? We want to connect with you! Email


Episode Resources:

National Research Council. 2007. Nutrient Requirements of Horses: Sixth Revised Edition. Washington, DC: The National Academies Press.


Katy Starr (00:01):

Hi, I'm Katy.


Dr. Tania Cubitt (00:02):

And I'm Dr. Cubitt. We're going Beyond the Barn. Come join us on this journey as we bust equine and livestock nutrition myths and interview some of the most intriguing experts in the country.


Katy Starr (00:15):

We'll go behind the scenes of how premium western quality forage is grown and brought to your favorite farm and ranch retail store. We're so glad you're here. Welcome back to another episode of Beyond the Barn. Dr. Duren, it is so great to have you back with us here.


Dr. Stephen Duren (00:34):

Thanks for having me.


Katy Starr (00:36):

We have a really interesting, fun topic that we get to chat about today about the history of equine nutrition.


Dr. Stephen Duren (00:43):

Yeah. Hopefully they'll find it as interesting as a nutrition nerd like myself does, but it should be good.


Katy Starr (00:49):

Yes. And this is something that's always been really, kind of, fascinating to me, especially more of the conversations that we've had together. But then, I think we initially also, kind of, got this interest peaked for us when we talked to Dr. Billquist last year with his episode and his history with working with the horses that are like in the army and things like that, in the military. And so, I think this is going to be an interesting topic for us to chat about, just how horse nutrition has changed over the years, the discoveries that we've made, and, kind of, where it all started too, at least for the domesticated horses. So, can you start off by talking to us a little bit about how did people in early centuries even determine what to feed their horses, considering the lack of scientific knowledge about equine nutrition at that time?


Dr. Stephen Duren (01:39):

Yeah, certainly they didn't have some of the modern conveniences we have of scientific literature. They certainly didn't have Google where they could just Google and figure out how to do something. So, a lot of the early feeding was based on observation. You know, they had to go out and capture these horses that were wild or certainly undomesticated. And in doing so, they made a lot of observations. What are they eating? Because if we take them out of that environment and we put them into our environment or a domesticated environment, we've got to mimic that because we don't have any idea what they ate. And that was some of the initial ways that they determined, certainly not the nutrient requirement of the animal, but just what do they eat? What do they prefer to eat?


Katy Starr (02:21):

What did they choose to eat when they were out on their own? Kind of?


Dr. Stephen Duren (02:24):

Yep, exactly. So, it was no more scientific than that is. We've taken this animal out of its native environment, we've put it into our environment. Good grief, what do we feed it? What did it eat when it was out there? We'll go get it or we'll get something similar. So, that's how they did it.


Katy Starr (02:41):

Excellent. What would you say, I mean, maybe you can start off by talking to us about, you know, some of the earlier times and where we were at. But we've had some notable changes and differences across the centuries as science has been put to work, there's been more people, kind of, paying attention to, you know, what is happening with the animals and actually doing some scientific studies to either prove a theory or what have you. So, can you talk to us a little bit about some of those changes that have occurred?


Dr. Stephen Duren (03:15):

Yeah, I think it's really interesting because if you go back in and you start looking and you say, you know, gee, I want to find out about this or that, as far as equine nutrition goes and you think that you're on some novel discovery and then you look back at how they fed horses or what they understood about horses in the first and second century, or certainly during the Civil War or the American Indian War and how they knew things that we took for granted. We, kind of, forgot and then we relearn. So, it's very interesting. But I think one of the striking differences of how horses used to be fed is they certainly didn't know the requirement for zinc or copper or for pregnancy or lactation, but what they did understand is they understood you had to feed them for the work they were doing. You had to provide enough calories. So, they were feeding more for body condition and body weight, maintenance of body weight, and didn't really understand all the other things that goes with, you know, feeding a horse so he can recover quicker and all those ramifications or feeding to keep the microbiome healthy. They were trying to say, what does this horse eat in his normal environment? How can we feed enough of that to get him to be able to do the work we're asking him to do?


Katy Starr (04:34):

Right. And how has it, kind of, changed? The population of horses, kind of, during the time of, you know, exploration of, kind of, like early America, you know, into like the civil war versus you know, now and everything? How has the number of horses, kind of, changed in that sense?


Dr. Stephen Duren (04:54):

Yeah, so they have changed. The other thing that's changed is the population. So, you say, well, you know, there's X number of horses today, but our population is a great deal higher than it was in 1870, for instance. So, if you look at horses per capita, they were much, much higher back then when they had to use these horses than they are now. So, you know, I've read some statistics in 1870, for instance. So, that would've been the height that when horses were used for transportation, not yet full-on farming yet, but lots of transportation, about 8.2 million horses. By 1900 they had swelled to 21.5 million. So, now we're starting to get a significant number of horses. And then, they peaked, at just the time you would think they peaked. They peaked about 1920, with 27 million horses. So, a tremendous number of horses. But it makes sense that the car had been invented, but it hadn't yet replaced horses for work. It hadn't fully replaced horses for transportation, at that particular time. So, that's when those numbers peaked. And then, now, if you look at the statistics now, I think we have just a little over 7 million horses. So, we're nowhere near the population that we had when we had to use those horses for mechanical work, when we had to use those horses for transportation, etcetera.


Katy Starr (06:23):

Well, and I know we're going to talk about this a little bit further on, but reading some of the information about the amount of horses that were used during some of the war times, just how many horses, because every cavalry person had a horse, maybe more than one. And just thinking about the numbers and how much they had to care for them and all of that stuff, like it's crazy to think about how high that number was to where we're at now. But it also, kind of, goes along with that change in time of how horses were used in the past, how they're used now. And so, I feel like that's just been such an interesting thing to, kind of, learn about.


Dr. Stephen Duren (07:06):

Yeah, for example, there are over 10,000 horses just involved in the American Indian War, just with 10 regiments of United States Calvary troops. That's 10,000 horses. Okay. So, that's a high number of horses. And that's not what the Native Americans had. You know, they would've had a high number of horses as well, because they used them for the same thing. It's as far as, you know, moving camp, transportation, hunting, all the things that they did. So, a tremendous need for horses, a tremendous importance for horses.


Katy Starr (07:40):

Right. Yeah, that's so interesting. And that's influenced their nutrition as well, when we think about the uses of horses. So, at that time, right, they were used a lot for transportation. And this has all changed through, I guess the timeframe there, but used for transportation, used for agricultural purposes significantly until, you know, we, kind of, hit that mechanical period of tractors came into play and all of that stuff. But then also for war, like we've talked about, and then now, horses in a lot of those ways, they aren't used really in any of those areas in the significant way that they are now. So, now it's more for pleasure and our, I guess I could say, you could say entertainment, but just hobbies, in how we use horses.


Dr. Stephen Duren (08:30):

Yeah. And that's true, except, you know, there are certain, obviously religious sects that don't utilize a mechanical power. So, with the exception of those, yes. Then horses become a recreation or a profession, or you're using those horses for competition. Now, those competitions can certainly generate ribbons or money or what have you, but certainly not as much, certainly today plowing fields and getting from point A to point B, as they were in the early 1900s.


Katy Starr (09:01):

Right. So, in your mind, doing some of the research that you've done and you know, gotten into for this topic, what do you feel like was the significance of horses during some of those different wartime periods for the US Calvary and the military and all of that?


Dr. Stephen Duren (09:19):

Well, they understood very, very clearly that the horse was everything. And some of the generals even said, you know, the calvary is entirely dependent on the horse, and everything must be done for the comfort and safety of that horse. And if you're a bit of a history buff and you read some of the excerpts of battle in the Civil War, in World War I, in the American Indian War, if you follow some of those, horses were so incredibly valuable that taking the enemy's horse or destroying the enemy's horse or having a horse of your own that got hurt or injured in some way, that affected your ability to charge, it affected your ability to retreat, it affected your ability to get materials from point A to point B. So, it really hampered or enhanced a war effort depending on what was going on with the horse. So, a lot of the calvary manuals, a lot of the things that we have on feeding horses, they were very specific on the horse is number one, we've got to take care of that horse.


Katy Starr (10:23):

Right. And you have mentioned previously, I think you said that your dad had an old manual?


Dr. Stephen Duren (10:31):

Yeah! I remember I was in graduate school and the rage then was, it was in the early eighties, so we were trying to look more specifically at exercise physiology. And we had some of the first equine treadmills where, you know, horses were running and we collect all these things. And I remember I was in his office, I was home on a break of some sort, and I was in his office, and he pulled out an exercise physiology manual from 20 years before that. Where they were looking at some of the same things, certainly not to the depth we were, but questions that I was wondering if had answers. And he was showing me they already had. And he goes, if you look back even further, there's more answers. And a classic example is we know that feeding different qualities of hay, different maturities of grass affect the digestibility.


Dr. Stephen Duren (11:22):

So, we know that very comfortably now. But ironically, in the first, second, and third centuries, that was a long time ago, they knew the same thing. They knew that certain grasses or certain hays were more fattening than others. So, they didn't understand the digestibility, they didn't understand calories or caloric density, but they realized this hay or this grass or this maturity of grass was better at feeding a horse that was working hard because it would help maintain his weight. So, I'm telling you, when you go back and look, there was a lot that they understood, just on observation, that now we're, I guess if you will, catching up from a scientific perspective saying, oh, that's because we've maximized the, or optimized the microbiome and we're getting more butyric acid, which is forming more glucose, and we know more about it scientifically. But trust me, they knew about it long before we ever thought about it.


Katy Starr (12:23):

It's like they knew what was happening, but they didn't know why it was happening. That why was kind of, I feel like what has been pieced together over the last few decades with research.


Dr. Stephen Duren (12:35):

Yep. There is no question, very few original thoughts, just adding clarification.


Katy Starr (12:40):

Yeah, that's so fascinating. So, how did the nutritional needs of war horses differ from those horses that were maybe used for agriculture or transportation?


Dr. Stephen Duren (12:51):

I think the biggest difference with the war horses is they didn't always know what feed they'd have. To contrast that, if a horse were on a farm, you had a pretty good idea of what he would eat on a daily basis. Okay, we grow corn, so they're going to eat corn. Okay, we grow meadow hay and they're going to eat meadow hay, or whatever it happens to be. On the contrary, when you're talking war horses, these horses are going over miles where they couldn't possibly pack all the fodder, or all the feed, that a horse would need, or a regiment of troops would need. So, they were packing the higher calorie stuff, they were packing grain, but would not pack hay. So, they were reliant on whatever they could find, and they chose campsites based on water and feed for animals. Okay? So, it wasn't that you finished a day of field work, and you went to a bunk, and that horse knew that he'd have the same hay every time and the same type of grain every time. With the war horses, the forage, which is the biggest component of the diet, would literally change season to season and where they were geographically.


Katy Starr (14:08):

And we were chatting about this a little bit before, but do you think with almost this uncertainty a little bit in the heavy reliance on that higher calorie feed, that this could have been potentially some of the earliest signs of where horses could have some issues with colic and digestive upset, you know, rather than earlier where they're, kind of, used to being in their more natural environment?


Dr. Stephen Duren (14:33):

Oh, there's no question. You don't read a lot about colic, but you look at the delay of replacement troops getting from point A to point B, you know, and me, because I'm a nutrition geek, I wonder if there was something nutritional that slowed those horses down. I wonder if those horses had been, you know, so many miles that they were fatigued. Or in the case of your question, I wonder if there was not enough natural forage and because they were allowing the calvary horse between 10 and 15 pounds of grain a day, if we got some digestive upset from that and we had some colic. Now, the one thing that would help eliminate colic on those types of horses is activity, because they're walking every single day, because they're traveling, they're moving material through that digestive system, moving gas through that digestive system. So, they certainly wouldn't have the gas colics that you would have, you know, with a horse kept in a stall because they're out all the time. But no question, they had to have colics, they had to have laminitis. Going across the Dakotas, where those horses were eating selenium accumulator plants, they had to slow down because they were having selenium toxicity issues. All those are known to have happened.


Katy Starr (15:47):

Yeah. Well and at that point too, I imagine like it's so much unknown territory, right? Like they're seeing these things happen, but maybe not realizing why they're happening. And so, it's taking them longer to, kind of, figure out, and maybe that's why they're needing more horses too, is because if a horse happened to get sick or something go wrong, it might have taken a little bit longer than, from what we know now, to get them back on their feet and to where they're feeling better again.


Dr. Stephen Duren (16:17):

Exactly. And a lot of those horses may not have gotten back or replaced, you know, they may have said, okay, that horse is sick, or that horse passed away, we need a replacement horse. Or in the case of war, we may borrow some horses from our enemy. So, stealing of horses. The horse was power. If you didn't have the horse, you couldn't certainly do a military parade of any kind.


Katy Starr (16:40):

Right. Yeah. That's amazing. Okay, so you mentioned about, you know, how they wouldn't pack hay, they'd pack grain on their long trips to, you know, from place to place and everything. But is there anything else that you can, kind of, add to about feeding challenges that were faced by armies, kind of, in maintaining the health and performance of their horses during wartime?


Dr. Stephen Duren (17:02):

Yeah, so again, they had to feed those horses. They had to come up with enough calories so those horses could go the distance they were asking. And typically those horses, depending on what they were doing and what the situation was, they go about 20 miles a day. Okay? At a walk and a trot. So, these horses are actually covering some ground. So, if they're going for that long, they'd take frequent breaks. And if they found a place where there was lots of grass and they would stop and let those horses pick up some natural forage, they'd stop in water. So, all those things were done, but they were a challenge. Depending on where you were, you didn't know what feed was going to be available. And so, that was a massive challenge that they had to overcome. And the wagons that were following, you know, with more supplies we're packing, concentrated supplies, grains and those sorts of things, rather than hay. So, finding the natural forage was critical.


Katy Starr (17:58):

I'm thinking about too, just how important water is. I mean, you know, there's always wild animals and everywhere, kind of, going out and finding water. But when you're moving in like that large of a group and having to go and not necessarily knowing where your next spot is for water, that could probably have also contributed a little bit to digestive issues if they had any of those.


Dr. Stephen Duren (18:22):

Yep, and dehydration. And once a horse dehydrates, they can't cover as much distance, all those things. And that's quite honestly why they used a lot of scouts, so that the scouts were actually ahead of the column of troops, knew where the water was, knew how far they had to get to water. So, they certainly weren't going blind, or totally blind. They had some idea, but you know, the next water is five miles, you got to go five miles. You know, there's no option to it. So.


Katy Starr (18:51):

Yeah, make it or don't. So, were there any notable innovations or advancements in equine nutrition that, kind of, emerged as a result of the horse's role in warfare? I mean, there's a lot of changes, observations, like we've talked about that they were able to determine. But what kinds of things happened over that time period, because it was a large use for horses. What kind of things, kind of, came from that?


Dr. Stephen Duren (19:18):

Yeah, so it's interesting, you know, they learned lots of things. Like for instance, what hays could be fed to horses. They learned more about storage of forage. They learned all that. They learned about types of grain. They learned about what grain was the most favorable to horses. They learned, certainly a lot of times we'll switch from grains depending on what's available, what we could get from a local farmer, what we could get to where these horses were. Other notable things is that calvary was the first group that actually started feeding salt to a horse. You know, so they started offering salt. Now, that didn't mean that that horses in the first, second, and third century didn't have salt, but they had to find natural sources of salt, or the sodium and chloride that are the natural ingredients. But the calvary was the first that started offering salt to horses.


Katy Starr (20:06):

Right. Yeah, that's interesting. Okay. And then, with the rise of mechanized transportation, how did the decline in the use of horses for work, and obviously this is a time period after a lot of the calvary use as well, but how did that affect, kind of, the use of the horse, their diets, and even their overall health?


Dr. Stephen Duren (20:29):

Yeah, so once we went from a horse that had to do the farm work or had to do the transportation and we started getting mechanized equipment to do that, then what we found is, as we talked about earlier, first, the population of horses dwindled. We didn't need as many horses. You didn't have to keep, you know, 20 head of draft horses to plow a field if you had a, you know, a tractor and that sort of thing. So, it's interesting from a science standpoint, science nearly stopped on equine nutrition. They didn't need to know anymore. They weren't as important anymore, as they were. So, we had a real lull in any of the manuals, if you will, I wouldn't call them scientific press, but more of the manuals on how to do things with horses. They just weren't done anymore because we didn't need it. And then, it wasn't until probably a 50-year span in there that we didn't have much happening with horses. And then, in the early sixties we started more for competition horses. Hey, let's figure out how much sodium they require, how much potassium. We started to discover all these other nutrients and we knew that horses had to have a requirement for them. So, we started working on some of those. And then, that, kind of, morphed into, you know, some of the more modern research that we're doing now.


Katy Starr (21:47):

And that timeline of ingredients, basically that, kind of, go into a horse's diet depending on, you know, how we use our horses now, their life stage, and things like that. We talk about, obviously fiber was the first and earliest thing that we noticed that they needed. They added in grains when they noticed that they needed more energy and calories. And then vitamins and minerals. And then oil, kind of, came after that?


Dr. Stephen Duren (22:12):

Yeah, absolutely. Oil, feeding fat to horses, that wasn't studied until the late seventies and early eighties when we defined more specifically, you know, the feeding of fat. First, you know, the animal fats, the processed animal fat that you'd feed to horses, and then to the vegetable oils. And now, we don't even concentrate on vegetable oil. We concentrate on what the omega-3, omega-6, and omega-9 content of the oil is, and other effects that it had. But it wasn't until the seventies that they fed much fat to horses, that we know of. But again, I think if you look back at, you know, some of the ingredients that they talked about in the different centuries, early centuries, first, second, and third, there were some of those grains that they were feeding that they weren't extracting the oil from. So, they were getting fat supplemented in the diet, but not like we think about fat supplemented in the diet.


Katy Starr (23:10):

Right. How we just directly add it. Right. Well, and we also talked about, and this is a common myth, Dr. Cubitt and I even did a podcast episode on this, episode 12. So, if you want to learn more about this and take a deeper dive into it, go listen to that episode. We talk about this, there is a misconception that horses are not able to digest oils because they don't have a gallbladder. Can you briefly touch on that?


Dr. Stephen Duren (23:36):

Yep, that is absolutely correct. So, there was a big discussion, I guess in the early seventies and late seventies that forage plants contain about 3% oil. And we think that horses may be able to digest that small amount of oil in there. But what about supplemental oil? What about adding corn oil or soybean oil, what were some of the original oils tested? What about if we added some of those to the diet? Could they digest those? And they can absolutely digest those, and we can feed up to 20% of the caloric requirement of a horse as fat. So, that's getting high, and you think, oh geez, 20% fat? But if you are driving down the road listening to this podcast, chewing on a fast-food delight of some sort, your dietary fat's much higher than 20%. So, even for horses, relative to human diets, they don't consume high fat diets, but we know we're able to supplement fat and they're highly digestible. The vegetable oils over 90% digestible. So, very digestible.


Katy Starr (24:41):

Right? So, go take a listen to episode 12 if you want to have more details and learn a little bit more about how horses are actually able to do that, since they don't have a gallbladder, because it can be done. It's very interesting. So, during this time period of where research, you know, is starting to pick back up again and everything, at what point did we actually first learn about the details of the horse's digestive system and, kind of, how it's laid out? So, where we have the small intestine, the large intestine, and all of that. When did that come?


Dr. Stephen Duren (25:12):

Well, you know, we would like to think it wasn't, you know, we defined that in some of the early textbooks, you know, of the 1900s. But I would dare say it was much, much earlier than that. You know, either the Germans or some of these early cultures had a pretty good idea. You know, if a horse got injured and they cut it open either for food or whatever, they began to notice the difference in the digestive tract compared to a a cow or a goat. So, I think a lot of that goes way back. I couldn't answer that exact question. I know that we had, certainly by the forties, we had a very good idea of what the digestive system was compared to other animals and some of the comparative physiology, we had that down certainly by that time. But I would dare say it was much, much earlier than that. If you, you know, peruse some of those ancient writings, you know, you may stumble across something that Aristotle said that you like, wow, how the heck did he know that? Or, you know, I think there's a lot of that.


Katy Starr (26:16):

Yeah. Well, and I imagine, kind of, similar to how they observed what horses ate, it was also a similar thing where they, kind of, noticed these different parts of the horse, but then maybe it took longer to figure out the why. Right? What is this? What happens in this part? What happens in this part and why is this part important? Things like that.


Dr. Stephen Duren (26:40):

Yep. There's no question. You know, I think they knew the parts. They didn't know certainly to the detail of what happens in those parts or certainly what happens on a cellular level. But they understood, definitely cause and effect. If I change the diet, you know, I can get a diarrhea. And then, they figured out if I change the diet, the gut sounds different. Well, how did they know that? They just listened. You know, they didn't have all the fancy things we have to, you know, study motility, but they understood.


Katy Starr (27:11):

Yeah. And at what point were we able to first determine, so you know, they were feeding grains to, kind of, get that extra calorie intake for those horses that were needing it. But when did we actually determine that maybe crushing certain grains improved the digestibility in horses?


Dr. Stephen Duren (27:29):

Well, I think we had known that again, for a long time. Horses that were involved in the milling industry, they ate a tremendous amount of wheat. And they understood that there was a difference in feeding them the whole wheat versus different byproducts, different crushed products like the flour or some of the hull was removed. They knew that there were different caloric values to that. But it wasn't until, probably the most detailed work that was done, was with the German research that was done in the seventies and eighties, where they very specifically started looking at not only is the grain 90% digested in the total tract, but where is it digested? You know, they started looking at different processing and increasing the surface area for enzyme digestion and where specifically that grain would be digested. And if it wasn't processed, what would happen to it? It would spill into that hindgut and get fermented. But we still wouldn't see grain, you know, in the manure, wasted grain in the manure. It was still utilized, but there were lots of ramifications on where it was digested and how ultimately, safe that it was for the horse.


Katy Starr (28:44):

Right, okay. And I think oftentimes we, kind of, take and look at some of the research that's being done in human research or to other animals and we, kind of, compare it across species just to, kind of, see, you know, if they discover something in some sort of research, then I think it makes them curious to know, I wonder if this is the same for other species. And so, it, kind of, takes them down another route of taking a look at that. And something that comes to mind when I think about that is like the microbiome, right? It's been so popular in human research and it's becoming, you know, more popular also in horses and even other species. And so, I'm just, kind of, wondering across the centuries, do you know if that was something that was, kind of, commonplace that happened over time to where that's how those kinds of things were figured out or looked further into? Was discovering something about a certain animal or about humans and then wondering maybe we should look at the horses and see how they're affected by this?


Dr. Stephen Duren (29:46):

Yeah, absolutely. You know, what we learned about ruminant animals and all the ruminant nutritionists that are trying to get a cow to produce more milk or a steer to gain more weight, they had a really good concept of the rumen microbiome and how they could change that and alter that. And then, I think it dawned on them one day that, well, horses eat forage. I wonder what their microbiome looks like. Well, when I first started graduate school, so that was in the eighties, late eighties, but when I was in graduate school, they had barely classified what bacteria were even in the horse's hindgut in the cecum and colon. So, a tremendous amount has been learned, but it was not until the seventies that we started identifying the specific bacteria. Okay? But again, Aristotle wrote that different hays and different maturities of grass affected the weight gain or the ability of a horse to maintain weight.


Dr. Stephen Duren (30:48):

So, those were influencing the microbiome, that fiber was more available to the microbiome. So, it's interesting, it took us a long time to put detail to it. And right now, as you mentioned, the equine microbiome is getting a ton of study. I would dare say we know precious little about it. I think we're just learning. And you talked about the microbiome and how important that is for a human, it's not even important for a human compared to how important it is for a horse. I mean, most humans don't rely on fiber as the only component of the diet, yet a horse can. So, the population, the extensiveness of the microbiome in a horse is much greater than it would be in a human. So, with all the attraction that it was in a human, you can imagine how important it would be in a horse.


Katy Starr (31:39):

Yeah. Now, that they're getting more figured out and still a lot not figured out yet .


Dr. Stephen Duren (31:44):

Yeah, true, true.


Katy Starr (31:45):

The more they figure out, the more they realize how little they know .


Dr. Stephen Duren (31:48):



Katy Starr (31:50):

And another thing that I was, kind of, curious about, I mean, we talked about, you know, the use of grain for quite a while back, but at what point did manufactured feeds actually come into play?


Dr. Stephen Duren (32:04):

It was much, much later, because even in, you know, certainly in pre centuries or early centuries, those people utilized grain that was either a byproduct or whatever they grew in a region. In the case of the calvary, the individual riders were responsible for getting the grain ration to the horse. Early race horses or competition horses, your best to mix your own so you can see what's in there, you can change them for the individual horse. So, the popularity of commercial feeds was way down the line as, as far as when they started to actually think about it and utilize that technology.


Katy Starr (32:46):

Yeah. One thing that I thought was interesting was some of the information that you had shared with me or sent over to me was, kind of, like at the early part of the century, the few manufactured feeds that actually even existed were pretty expensive, and the ingredients were of poor quality, like that they had used ground corn stalks and sawdust.


Dr. Stephen Duren (33:09):

Exactly. So, if you're going to make a commercial feed, you'd only make a commercial feed out of what products you couldn't use in whatever you were doing. So, again, we mentioned the horses that were involved in the milling, they ate a tremendous amount of wheat bran. Well, wheat bran is very unbalanced, or non balanced, with respect to calcium phosphorus. So, those horses actually developed a disease, big-head disease, because of a calcium balance issue that was going on because of the high phosphorus gut diet. So, we learned about that, then we started, huh, I wonder if this is important. And then, learning more about calcium and phosphorus and all those sorts of things.


Katy Starr (33:49):

Right. And then, getting some standardized things in place to make sure that it was being done well. Yeah.


Dr. Stephen Duren (33:55):

Exactly. But I mean, we've had pelleted feeds have been fed to horses since the sixties, since the 1960s. But the quality of those pellets, and even today, people always wonder because they can't see the individual grains in there. Are they sweeping the floor? Are they putting sawdust? Are those, so that's how all that got started is because, especially with pelleted physical forms of feed, you couldn't see what was in there.


Katy Starr (34:23):

Right, and I think, you know, being able to do things like putting on, kind of, a guaranteed analysis and things like that, listing the ingredients that are in the bag, when you, kind of, put a number of these things together, it kind of, showcases for the consumer or the horse owner that, "Hey, this is how you know what's in here. This is how you can, you know, ensure that you're getting what you know that you're getting for your animal."


Dr. Stephen Duren (34:47):

Exactly. Yet, we still have to be Aristotle and look at our horse. How is he doing on this feed? And that's the real proof, is the eye of the master, you know, fattens the horse, you know, in other words, your observation and what you're seeing will tell you how good that feed is, will tell you how good that forage is. Just because an ingredient is listed on the label, you know, is it processed correctly? Is there enough of it? You know, those sorts of things become an issue.


Katy Starr (35:18):

And probably because horses are so different, some of them do well on certain feeds and others do not do as well on other feeds, knowing what works for your horse.


Dr. Stephen Duren (35:29):

Yep. No question. And you know, how hard your horse is working, you know, and all those things will make a difference on how well the feed is utilized by the horse.


Katy Starr (35:40):

Right. And so, in a lot of our podcast episodes, Dr. Cubitt has referenced the National Research Council's Nutrient Requirements for Horses, and it's currently in its sixth revised edition. When was the first edition established and what have been some of the most significant changes from the first to the six editions?


Dr. Stephen Duren (36:01):

Yeah, so the first edition was actually in the early sixties. It was 1961. But proceeding that document, there was a document, a manual, a feeding manual if you will, that was dated in 49. So, ironically, right at the tail end of what I'd like to think is everything we knew about horses. You know, we knew which grains, we knew all these things about horses, we didn't know in the detail, but we knew a lot about the husbandry of an animal because we used them on a daily basis. And since then, we've had a number of revisions, as you mentioned, from 1961, we're now on our sixth revision, which was 2007. So, we learned more detail. So, the first ones were just talking about what I would consider simple things. We're talking about energetics and proteins and things like that. And now we're talking about amino acids, we're talking about omega-3 fatty acids.


Dr. Stephen Duren (37:00):

We're talking about the microbiome. We're talking about a lot different things than we were before. Probably the biggest one is we're talking about minerals and vitamins. You know, certainly the calvary horses, they didn't know anything about, well, I don't think, about minerals and vitamins. Yet, they were the first to start feeding salt to horses that we know of. But now, we know what the sodium requirement is, we know what the chloride requirement is, we know what copper and zinc and manganese, and all those things are. We didn't know those. So, as we progress in equine nutrition, I think some of the new developments are going to be, how do we get horses to recover quicker? How do we get horses to do things more efficiently? I think the other thing that we're going to see is, how do we continue to feed horses on more byproducts?


Dr. Stephen Duren (37:49):

Things that aren't in human consumption, as we struggle with the amount of agricultural land and the world population in feeding animals for human consumption and feeding grains for human consumption. Where does a horse fit in? Because most countries, as you know, do not consume horse meat. There are some, but not a lot. They're not used for primary transportation. They're not used for primary mechanical strength, as far as farming. So, why should horses get grain? You know, why shouldn't we give it to the children or to the, you know, other places that these humans need the grain. So, I think a lot more of our science is how can we do things with more fiber products and more byproducts? And I like to, not necessarily think of an ingredient as a good ingredient or a bad ingredient, what does that ingredient bring to the table? Is it safe to feed? And I think that's where, in my opinion, I think we'll see a lot of the science go is how can we feed these horses on useful byproducts that are safe for the horse, certainly, but also effective as far as being able to provide adequate nutrition.


Katy Starr (39:00):

Right. Yeah, that's definitely, as the population on earth grows, and that's going to be something that we don't think we need to think about now, but come 50, a hundred years, there's going to be some changes, I think, in a lot of those areas.


Dr. Stephen Duren (39:14):

Well, if you think that the calvary used to feed between 10 and 15 pounds of grain a day, the amount of horses that would get 10 or 15 pounds of grain today are much fewer, lower percentage, than they did at that day. So, we've gotten better at forage, we've gotten better at byproducts, beet pulp, things like that, that can go into that horse's diet.


Katy Starr (39:36):

Between that and then the efficiencies in farming that now occur to where we can produce more with less land. So, there's been a lot of changes that have occurred.


Dr. Stephen Duren (39:46):

Yep, although when you buy your tractor, they still rate it in what? Horsepower.


Katy Starr (39:50):

Yes, yes. That never changes. .


Dr. Stephen Duren (39:53):

So, that tells you how important. Exactly.


Katy Starr (39:56):

Yeah, that's a good point. Dr. Duren, as we, kind of, wrap this episode up, from your perspective as an equine nutritionist that is working with horse owners, what have been some of the most helpful improvements made to equine nutrition that we've discovered over the years of research? What have been some of your favorite that you feel like have been the most beneficial?


Dr. Stephen Duren (40:22):

I think that understanding the mineral requirements of horses has been critical. That has led to more foals being born structurally sound, and then being able to maintain a soundness through a performance career or an athletic career that we as humans decide we want that animal to perform. So, I think a lot of the mineral research has been very interesting. I think a lot of that exercise physiology work has been very interesting from my own perspective, seeing just how good of an athlete the horse is, especially compared to humans, you know, how quickly they reach their potential. Whereas, you know, humans are still breaking records all the time, yet horse records aren't being broken as much. They achieve their potential much quicker. And you know, from studies are vastly superior athletes. So, I think that's been interesting. Other things, you know, more of the simplistic things, you know, the digestibility of different ingredients, the calorie contents of different ingredients, how much a horse can get out of different things has really helped, from a formulation standpoint. So, that's what I would say are probably the biggest benefits that I've seen.


Katy Starr (41:35):

Well, and you know, obviously the use of the horse has changed significantly over the years, but with this discovery of, you know, this scientific research, it's really improved the health of the horse. When you think about how long the lifespan has been for horses, you know, in the early century, early part of this century, to where we're at now and how some are living into their forties, like it just, kind of, goes to show just how much we've been able to improve things. Like when you talk about vitamins and minerals, right? Not just that, but how they interact with each other and being able to prevent diseases like big head disease and things like that.


Dr. Stephen Duren (42:18):

Yeah, certainly. I think the biggest challenge we have now is that our horses aren't going 20 miles a day, that they aren't being used adequately. Because a lot of the diseases that we're finding in horses today, unfortunately, are inflammatory type diseases that are, in a lot of cases, fueled by obesity. You know, these horses simply aren't getting enough miles, they aren't getting enough turnout, they're not getting enough variation in forage types that would occur even on a natural pasture. And I think, we're creating a whole new set of challenges for equine nutritionists. It's not, sometimes I think it'd be easier to feed a calvary horse, where I knew what he was going to do and he was going to be put in a certain situation every single day, than a competitive show horse. Okay, he's in Miami this week competing in a Grand Prix, then he flies back to Canada, he's home for three weeks, and then he's in California.


Dr. Stephen Duren (43:17):

And the difference in ingredients and those sorts of things, the difference in workload and all that is tremendous. And that's probably even easier than dealing with a backyard pony. You know, God forbid it becomes spring and they want to turn the horse out because they're tired of feeding hay and they turn it out on a pasture because it's not growing very fast, is accumulating lots of sugar and the horse gets laminitic So, those are hard horses to feed, you know, a horse that went 20 miles a day or was used for plowing, they may be the easier type to feed.


Katy Starr (43:50):

Right? So, it's almost like, now we've got all this information, kind of, at our fingertips. So, now it's all a matter of, kind of, balancing this like we're juggling, and we need to figure out a way to balance it, and figure it out to get it right at the right point for each horse and, kind of, what works for them.


Dr. Stephen Duren (44:06):

And there's no question, but again, it still goes back to the things they did in the early centuries where it's observation. You know, you've got to know your horse better than anybody, and you've got to know, you know, what upsets him and you know, all those things and put together and then, you know, take advantage of the technology that we have. We have very good commercial feeds for horses, you know, that have the correct amount of vitamins and minerals that you don't have to put together necessarily, unless you have a desire to do that. You don't have to buy all the individual grains and grind them or process them. That's all taken care of for you. So, it's relatively easy. You just got to, kind of, follow the directions. 


Katy Starr (44:43):

Yeah. Excellent. Well, Dr. Duren, thanks so much for being on today. It was really interesting to, kind of, learn about, you know, the changes that have occurred in equine nutrition over time at different points in time and how horses were used, and hopefully our listeners appreciated it as well.


Dr. Stephen Duren (45:00):

Well, good. Hope you enjoyed it.


Katy Starr (45:01):

And to our listeners, thank you so much for being here with us. If you have topic ideas that you would like us to talk about on the podcast, please feel free to reach out to us at And thanks again, Dr. Duren, we'll talk to you later.


Dr. Stephen Duren (45:16):

Thank you.


Katy Starr (45:18):

Thanks for listening to the Beyond the Barn podcast by Standlee Forage. We'd love for you to share our podcast with your favorite people, and subscribe on Apple, Spotify, or your favorite listening platform. Until next time, keep your cinch tight, and don't forget to turn off the water.


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