Carbohydrates - Demystified

As you know by now, I have Bean, a Thoroughbred, who in typical Thoroughbred fashion can lose weight with one desperate whinny, so coming up with a feeding program that keeps him calm but keeps him fit is a constant challenge. And, with the buzz going around about carbohydrates being the number one contributor to everything from colic and laminitis to hyperactivity and nervousness, with developmental orthopedic diseases (DOD) and Cushing’s Disease thrown into the mix, I’m beginning to wonder: are carbohydrates a help or a hindrance to the equine diet? I figured if anyone would know, Larry Lawrence, PhD, Nutritionist at Kentucky Equine Research would, so I asked . . . And, here’s what he had to say . . .

Understanding Digestion

Having exceptionally small stomachs, horses are limited in their ability to absorb nutrients from large quantities of food at one time, a holdover from their days in the wild. Because they can forage up to 20 hours a day, the stomach needs to process food quickly, between 30 to 90 minutes before passing it on.

The small intestine is the next stop where the majority of the nutrients, including protein, some carbohydrates, and fat are digested, and where many essential vitamins and minerals are absorbed. From there, the digestive matter and liquids continue on to the cecum and colon (hind-gut), which digests fiber (insoluble carbohydrates) and the remaining soluble carbohydrates (starches and sugars).

Understanding Carbohydrates

There are six main categories of nutrients necessary to a horse’s survival – water, carbohydrates, protein, fats, vitamins, and minerals. While energy isn’t a category, next to water, almost 90% of a horse’s nutrient intake is required to fulfill this critical requirement, and where carbohydrates, soluble and non-soluble, come in.

Soluble Carbohydrates

Soluble carbohydrates (starches and sugars) are broken down into simple sugars (glucose) in the stomach and small intestine where they are eventually absorbed into the blood stream. The hormone, insulin, continues the process by transferring glucose from the blood to the liver and muscles where it is stored for utilization on demand. This energy reserve, known as glycogen, is the resource that provides immediate power bursts critical for all horses, but especially horses involved in intense anaerobic sports such as racing. The starch from corn, oats, barley, and molasses are the most common sources of soluble carbohydrates

Insoluble Carbohydrates

Unlike soluble carbohydrates, insoluble carbohydrates are derived from the fiber source, cellulose, which is digested in the hind-gut. Taking 24+ hours to process, insoluble carbohydrates are transformed into volatile fatty acids, which are absorbed and held by the liver as an additional energy source. Forages such as hay, grass, beet pulp, and soybean hulls are the main suppliers of insoluble carbohydrates.

Understanding the Relationship between the Two

Trouble often starts when feeding excessive amounts of soluble carbohydrates. Because there may not be sufficient time for the starches to be broken down in the stomach before reaching the small intestine, glucose and insulin can flood the blood stream causing metabolic upsets particularly in the young developing or senior horse, as well as hyper-excitability and behavioral problems across the board. Alternatively, when the starches are not adequately broken down, they enter the hind-gut and rapidly ferment, which is where disorders like colic and founder originate.

Insoluble carbohydrates (fiber), on the other hand, are fundamental to an efficient digestive system (horses can live on fiber alone as an energy source), and therefore should not be compromised in an effort to reduce starches and sugars in the diet. A general guide line is to feed at least one to two pounds for every 100 pounds of weight per day. For example, a 1,000 pound adult horse would need approximately 10 – 20 pounds of hay and may be fed even more depending on its workload and condition.

Research shows that by increasing dietary fiber and fat (fat is the densest form of energy and is considered effective in controlling the rate at which glucose is released into the system), while reducing starch and sugar intake will benefit the overall health of horses participating in light to intense performance or pleasure activities while at the same time reducing the risks linked with starch overload.

Cool deal, Larry; thanks for making a mole hill out of a mountain?

Equine Gastric Ulcer Syndrome (EGUS)

I know I’ve mentioned this before - I do foster/lay up care for off the track Thoroughbreds through CANTER New England - my heart’s work. And, I’m sure I’ve also mentioned that I fall in love with every new horse that comes on the yard. Like take my latest arrival, Black Rainbow who I dubbed, My Little One. He got to the farm in really bad shape. He was so thin you could play the harp on his ribs, and not surprisingly he was lethargic, his coat was dull, he had chronic diarrhea, and the most disturbing thing of all in my book, he had a worried, distrustful look in his eye when he’d even bother to look, that is; I was really afraid he’d given up.

Since it’s a known fact that a daunting 90% of racehorses and another 60% of show horses have ulcers, with untold numbers that are mostly confined to stalls probably in the mix as well, and because gastroscopy was not a financial option, I decided I’d better treat My Little One accordingly just the same. So, I slowly transitioned him to a high fiber, high fat pelleted feed to which I added probiotics and freshly ground flax seeds before turning him out from dawn ‘til dusk with enough hay to feed an elephant (when I tried to add soaked beet pulp to his diet, he’d relapsed back to having diarrhea, so I bailed on that idea).

Over time, I’m relieved to say, he started to rally and even learned to relax a bit – touching his ears and eyes took some time, though. Then, all of a sudden one day he re-connected, and with a vengeance. I practically had to peel him off the ceiling – if he wasn’t up on his hind legs, he was jumping, kicking and tossing his head, especially at meal time. It was wild. Over time and with a lot of work, however, we came to terms and he eventually became a total lovey. And, on the physical side – he gained enough weight to achieve an optimum ‘5’ on the Henneke Body Scoring Scale. Yet, with such a dramatic change in his temperament, I couldn’t help but wonder that maybe some of the behavioral challenges people face, from apathy to off the charts, are as a result of their horses having been plagued by Equine Gastric Ulcer Syndrome (EGUS), leading me to ask: how can you tell what’s a reaction to pain and what’s just plain rude?

That’s what I posed to Frank Andrews, DVM, MS, Dipl. ACVIM and professor at the University of Tennessee College of Veterinary Medicine. Here’re the Cliff Notes of what he said. “It’s not the behavior as it is the change in behavior that alerts us to the possibility of a physical problem.” He cited two examples: the horse that normally has a good attitude, who for no apparent reason becomes mean spirited – ears pinned back or nipping, and the horse whose performance has declined, again for no obvious reason. So, how does EGUS happen? “You could make a case for stress being a prime contributor, that and poor nutrition management,” he said. He went on to explain that a horse’s saliva is bicarbonate rich in addition to having special coating agents to buffer and ultimately neutralize stomach acids - why the chewing process is vital to proper digestion. Consequently, if a horse is too fidgety to eat, or only gets fed twice a day with a token serving of hay (ideally he should be offered as much as he’ll eat), he’ll likely not be able to counteract the effect of the acids churning around. “And, because the esophagus extends into the stomach,” Dr. Andrews pointed out that a horse is, “as subject to acid reflux as we are.”

And, so it goes to show, once My Little One was back up to speed, he picked up where he left off – only better. Armed with good looks and good manners, the story has a happy ending; he’s now happily ensconced in the lap of horse luxury. Not only does he have a pasture mate with whom he shares hay and whose withers he often nibbles, I’m told, but he also has the ideal adoptive parents as well – a devoted equine and small animal veterinarian couple. Wow! It doesn’t get better than that.

Pasture Mates

I don’t know about everybody else, but my heart’s always in my throat whenever I introduce a new member to the herd, even though in this case, the herd consists of my horse, Bean, and his second-in-command, Freddie. It wasn’t always that way, however. Having been at the bottom of the totem pole for most of our eight years together, it wasn’t until he came to the farm that he now calls home that Bean finally stepped up to the plate and, after a lot of ranting, raving and chest thumping, emerged as number one. I must confess, I was secretly glad; I just couldn’t rationalize my then 14-year-old, 16.1 H Thoroughbred being bossed around by a three-year-old, barely 15 H Morgan, but horse hierarchy is anything but linear.

To that point, I’m now fostering a magnificent descendant of the Triple Crown Winner, Secretariat, I call Striker who stands 16.2 H and is as solid as The Rock of Gibraltar (I know, I gush about all the horses who come under my wing). Anyway, since I don’t have another charge on the yard right now, he has his own pasture next door to my crew. Nevertheless, I’d often notice him lingering around the fence waiting to play, so one afternoon when everyone was hanging out, I took the plunge and put him in with the boys . . . Big mistake. After watching little Freddie terrorize poor Striker, as big as he is, for three days in row, I accepted the fact that it wasn’t going to work.

According to the American Heritage Dictionary, a bully is, “A person who is habitually cruel or overbearing, especially to smaller or weaker people,” which rang a bell here, and which got me to wondering, how different is one species of bullies from another? That’s when I contacted Dr. Betsy Greene, Equine Specialist at the University of Vermont to get her read on the matter. Here’re the highlights of our conversation:

¨ Horses will always have herd animal instincts, no matter how old or how much training they have; their pecking order helps them feel comfortable with group dynamics, even the “bottom” horse can be happy in his role

¨ When you put a new horse into an established hierarchy, the order must be sorted out all over again, hence the challenging, kicking and fighting

¨ The highest ranking horse gets first dibs on territory, food, and water, which he might defend vehemently, so it’s important to precede with caution. Take your time and provide an escape route for the lower ranking horse to get out of harm’s way

¨ If it’s possible, allow the horses to meet over the fence in adjoining paddocks. While sniffing noses often leads to the inevitable squealing, head tossing, and pawing, it’s the process by which they begin to determine their order. But, if you need to put the horses together immediately, it’s best to turn them out after a meal to avoid disputes over feed. And, be sure to stay nearby until they settle down

¨ You may want to keep the halters on the first few times they are together, but be very cautious of trying to interfere with their natural process or you may end up in a precarious or dangerous position. Unless there is continued conflict, most horses will work out their differences in a few hours or days

¨ On the other hand, if one horse is continually disturbing or threatening the other, or if there is an out-and-out battle, which may include multiple chase scenes with ears pinned back and teeth barred, they should be separated

¨ Even when the order’s been established, the pasture should allow each horse adequate room to stand freely around the hay feeder, or divide the hay into more piles than horses far enough apart to keep the dominant horse from controlling the food. The same applies to the water tank and run-in shelter; the submissive horse must have enough room to move away

So, it just goes to show - as harsh a commentary for horses as it is for people . . . a bully by any other name is still a bully.