This probably comes as no surprise, but the horse is a unique animal.
This is especially true when it comes to how they digest food. Classified as non-ruminant herbivores, horses’ digestive systems are a cross between a monogastric animal (like a dog or human) and a ruminant (like a cow or goat).
The problem is that many people feed their horse like they would a dog or themselves—with two or three meals given throughout the day. This can work, but it often leads to problems. If more people understood more how the horse’s digestive system functioned, they might be more inclined to feed their horse like a horse.
With that in mind, here are 16 facts that will help you better understand horse digestion. And since digestion begins in the mouth, we’ll begin there and work our way down and out...
Fact #1: Horses can only chew on one side of their mouth at a time.
They do this not with an up-and-down motion, as we do, but an outside-to-inside motion on a slant, which is determined by the slant of the matching surfaces of the upper and lower cheek teeth.
Fact #2: The horse can produce up to ten gallons of saliva per day if allowed to eat plenty of forage.
As the horse chews, the salivary glands produce saliva to help moisten the food and ease its passage into the esophagus and stomach. Saliva also neutralizes stomach acids, therefore reducing the risk of gastric ulcers.
Fact #3: The horse’s esophagus only works in one direction.
The esophagus empties into the stomach. Food can go down, but cannot come back up. So it’s true—horses cannot vomit.
Fact #4: The horse’s stomach can only hold about two gallons.
It is quite small in size when compared to other parts of the digestive system.
Fact #5: Food only remains in the horse’s stomach for around 15 minutes.
From there, it moves into the small intestine.
Fact #6: When the stomach is empty, acid can attack the squamous cells in the stomach lining.
This often results in ulcers and is why small frequent meals, access to a slow feed hay net, free-choice hay, or access to pasture are very important.
Fact #7: The majority of the digestion occurs in the horse’s small intestine.
The same holds true for the absorption of sugars, starches, proteins, and fats.
Fact #8: Horses do not have a gall bladder.
Instead, a segment of small intestine called the duodenum aids in the digestion of fats.
Fact #9: Food can only enter and exit the cecum (also known as the ‘blind gut’) from the top.
If a horse doesn’t have adequate water intake, this can be a common site for impaction colic.
Fact #10: The cecum and other parts of the large intestine contain active populations of bacteria and other microbes.
These bacteria and microbes help break food down in a process called fermentation.
Fact #11: The bacterial and microbe populations become specific in fermenting the type of food the horse normally eats.
When a new food is introduced suddenly, the bacteria/microbes are unable to ferment it effectively, which may result in colic. This is why all feed changes should be made very gradually.
Fact #12: Lignin, a type of dietary fiber abundant in overly mature hay, cannot be broken down by fermentation.
Therefore, it is passed in the feces.
Fact #13: Gut sounds (borborigmus) are a sign that food is moving through the digestive tract.
An absence of gut sounds can mean there is a blockage.
Fact #14: A horse requires a minimum of 1% of his body weight daily of long-stemmed roughage (grass, hay, or hay replacers) for normal digestive tract activity.
This would amount to ten pounds of roughage for a 1000 pound horse.
Fact #15: On average, the entire digestive process for the horse takes anywhere from 36-72 hours.
That’s from mouth to manure.
Fact #16: If it were to be stretched from end to end, the horse’s digestive tract would measure about 100 feet in length!
Most of this is intestines.