The Beginner’s Guide to the Equine Digestive System
Horses have an extraordinarily large digestive system — compared to humans they have more than double the length if you were to place them side-by-side, start to finish! This long path for food digestion is packed with twists and turns (and the inability to vomit), so it’s easy to see how digestive upsets can occur in our equine partners. Below is a quick overview to give you a better understanding of how we can feed to our horses’ needs while keeping in mind how they evolved.
Down (or Up!) the Hatch
Photo: Shutterstock/Kimberly Watley
Two of the most important functions of horse lips are sifting through food and helping the tongue push it back to the molars as the horse continuously grazes and chews. Chewing of forage is essential — not only does it make sure tough stalks are ground to prevent impactions, but the chewing action produces saliva to lubricate the food as it passes through the tract. Healthy teeth and access to free-choice forage are imperative to a healthy start to the digestive process.
Horses naturally graze with their heads down, so food is transported up the esophagus by strong muscle contractions to the stomach. The stomach is located at an angle to the esophagus that makes regurgitation impossible, which is why digestive issues can be so scary in horses. The equine stomach is also incredibly small for such a large animal — it empties quickly but continuously produces acid. If the stomach is not kept relatively full, acid can begin splashing up to the upper region of the stomach, creating ulcers.
Intestines and the Hindgut
Like the stomach, food also travels rather quickly through almost 70 feet of intestine, and this is the site where most carbohydrates and proteins are absorbed by enzymes. After that long journey, food continues to the hindgut — this is where horses get their classification as “hindgut fermenters.” This area is home to a huge population of microbes and bacteria species, which are needed to break down remaining nutrients.
Water and vitamins are heavily absorbed here, while fibre is broken down by the microbes, producing needed calories. If dehydrated, this is the likely area of the horses’ tract that is susceptible to impaction colic.
The cecum houses all those microbes, whose populations vary depending on what the equine diet consists of. Ideally, most non-structural carbohydrates (NSCs) will be absorbed in the foregut by enzymes, leaving fibrous materials to be digested here by microbes for hours. The goal is to make sure the microbial population is happy and flourishing. This is achieved by ensuring that horses always have a healthy intake of fibrous material in their diet.
Keeping an eye on your horses’ poop balls is a good indication of their overall health since this is the end of the journey. Diarrhea is usually the result of undigested food or quick feed changes. On the other hand, if you notice your horses’ poop balls are very dry, you should increase their water intake by providing loose salt in their diet to prevent potential blockages.
What This Means for Feeding
The equine digestive tract is fascinating, unique, and full of twists and turns (literally), so it’s important that we feed to our horses’ needs. Although modern horses live a much different life than their ancestors did, their digestive process is very much the same. We want to be cognizant of their natural process, while also providing the nutritional requirements for the active horse of today.
Long-stem forage is the foundation diet for a healthy horse. Remember that saliva is needed to prevent ulcers, ensure safe feedstuff travels through the tract, and to keep the hindgut microbial population happy. For horses that have trouble chewing, such as seniors, a fibre replacement product must be included in the diet.
Depending on individual needs, a ration balancer or complete feed for the working horse compliments a forage-based diet. Smaller and more frequent meals are best practice. Most horses require extra calories and nutrients in order to perform, so being able to provide two or three smaller concentrated meals will optimize the absorption of vitamins and minerals while also making sure most NSCs are absorbed before reaching the hindgut.
Creating a happy, healthy horse means providing a feed plan that caters to both their evolutionary instincts as well as their specialized modern needs in sport and recreation.
Main Photo: Shutterstock/Osetrik