The horse is designed
to be a grazing animal. The small stomach and expansive lower digestive
system have developed to digest fiber from pasture grasses. By working to
the horses strengths, we can maximize their digestive efficiency. This is
a key part in performance horses, but equally important to all of us in keeping
our horses healthy on a cost effective ration.
As horse lovers we have the responsibility to
provide food, water, and a safe environment. For love of our horse or a
desired level of performance we seek to supplement their diets. Most of
the equine communities I work with have an opinion on feeding the horse. I
have found that most can benefit from the advice of a professional in balancing
their horse’s nutrition.
Nutrition and genetics are critical factors in
your horse’s health, performance, and reproduction. Long before that foal
hits the ground, nutrition is important to ensure its good health. Every
day after that nutrition affects that horse’s energy, stamina, and health.
So let us look at what your horse can eat and how
we can feed them well without breaking the budget. Your horse can eat
anything they can chew, but they digest and get nutrition from fiber (70% of
diet), protein, glucose, fructose, starch (not over 25% of diet) and fat.
Now telling your uncle that your horse can digest fat will make his eyes do that
thing they do when you try and explain your computer network problems at work.
But the average 1000-pound horse can eat the equivalent of four pounds of butter
a day. I agree that would be too gross to watch, but it would give them a
lot of calories which are the things that produce heat, energy, and a shiny
coat. Gee, that sounds a lot like corn? Corn is fed to people, hogs,
dogs, cattle, etc. So, why not to your horse? Because your horse has
evolved to digest fiber,not starch. My large animal surgery professor once
said, “The horse’s digestive system looked like it was designed by committee.”
Yes, it does pose some challenges to the equine surgeon trying to save a horse
from colic. But, for digesting fiber it rocks! Let us take a short look at
how your horse digests its food to understand what we want to feed them. I
promise to keep this simple.
Remember the horse has evolved to digest fiber
not starch, so only a quarter of the digestive enzymes and microbes in the horse
intestine can break starch down. If we feed too much starch it does not
get digested and passes through to the large intestine where it ferments and
causes problems.
What is fiber? To the horse it is pasture
grass and hay. To your veterinarian or an equine nutritionist it is
divided into digestible and indigestible fiber. The horse chews their food to
break open the cell walls of the plants and grains. The plants have used
energy from the sun to form the bonds of structural carbohydrates that make
fiber. Enzymes in saliva (spit) and the horse’s digestive tract, along
with microorganisms break these bonds and release the energy to let the horse
grow, stay warm, and carry us around. Seventy percent of your
horse’s total energy comes from the digestion of fiber. This is where you
want to put your money. Buy good quality forage with digestible fiber.
Digestible fiber is a polysaccharide such as cellulose, a six carbon sugar
C6H12O6 called glucose held together by beta bonds, and Hemicellulose, a five
carbon sugar held together by beta bonds. Non-fiber carbohydrates are six
carbon sugars held together by alpha bonds (the nastiest). These
polysaccharides are starch.
The stomach and small intestine digest starch,
fat, and protein, and absorb most vitamins and minerals. The large
intestine, cecum, and colon ferment and break down fiber and produce B-vitamins.
B-vitamins are so important and are key to metabolism. Your horse needs
them every day, and makes them from the fermentation of fiber.
Depending on the size of the horse, the stomach
holds 6-12 quarts. The small intestine is seventy feet long and holds 48
quarts. The cecum is the size of my leg and holds 30 quarts, and the colon
holds 80 quarts. Compare this to the cow, a real corn burner.
The cow has the bulk of it’s volume in the front of its digestive tract.
The four compartment fore-stomach ferments starches before they pass through the
glandular stomach and small intestine. In this way the starch from corn
does not get to the fiber digesting colon. The poor horse does not have a
rumen, so the starch in corn passes to the colon. Only 25% of the
digestive enzymes in the colon digest starches, so it hangs around and rapidly
ferments causing acidosis and killing off many beneficial fiber digesting
organisms.
This has been associated with insulin resistance,
gastric ulcers, laminitis, growth rate fluctuations, flexure deformities,
hyperlipidemia, oxidative stress, typhlitis, colitis, diarrhea, and colic.
Bad. Remember the indigestible fiber? This is the stuff “hay bellies” are
made from. It is Lignin. Lignin is indigestible fiber, wood,
or poor quality hay. The only things that get energy out of lignin are
termites and fire.
