Understanding the Horse’s Digestive System

Horse Digestion

Whether it is an animal, plant or other living organism, all living things must have a genetic code and chemical process to maintain life. All living organisms have nutrient requirements that are basically the same at the metabolic level. The difference is how these requirements are absorbed to provide nutrients and energy to live. For example, plants can manufacture the nutrients and energy they need by staying in one place. They can do this by using the energy from sunlight, along with water, oxygen and nutrients from the soil. In essence, they are self-sufficient.  Unlike animal life, plants do not depend on other living things to survive except for the soil microbiome at their roots.

Although horses belong to the same animal class as humans and other mammals, they are metabolically smarter than most other mammals. The nutrient requirements between horses and other mammals are the same at the metabolic level; however the horse’s ability to manufacture nutrients is far more advanced. Humans, for example, must obtain most nutrients they need directly from what they consume. The food and nutrients are delivered to the digestive tract, broken down, and provided to the rest of the body. A horse’s digestion process is much more complex than this. This is in large part due to the hindgut (including cecum and large intestine) of the horse.

The cecum is a large organ within the digestive tract that houses microorganisms. These microorganisms break down the fiber and cellulose the horse consumes and converts the cellulose into additional nutrients and energy that the horse needs to survive. So unlike humans and other monogastric mammals which eat and drink to consume nutrients that are ultimately absorbed, horses not only eat and drink to absorb nutrients but also to feed the microorganism factory within their cecum.

To simplify this process, we can think of the cecum as a “garden” for the horse. This garden enables horses to be mobile in order to consume the nutrients they need. Horses fertilize the garden with the energy and nutrients needed to thrive by providing it with the cellulose of the plants consumed. The garden then produces the “fruits”, or additional nutrients, the horse requires.

Before the domestication of horses they were naturally roamers. They would roam, graze, and find the proper nutrition they needed to fully provide for the hindgut microorganisms. Today, we have restricted the horse’s ability to do this by enclosing them in pastures, paddocks, and barns. We have also increased their natural calorie needs by demanding more of them through riding, training, athletics, and work. Modern feeding practices have altered the natural diet of the horse.  Many complete feeds contain excess fats and sugars (molasses), and are also fortified with additional nutrients. This “all-in-one” concept tethers calories and nutrients together; therefore hard keepers and working horses must consume large amounts of the fortified feed to maintain body weight. This often results in over-supplementation of nutrients, and a diet too rich in fats and carbohydrates. On the other hand, easy keepers are often under-supplemented using this method of feeding. Also note that horses do not have gallbladders. Without a gallbladder the horse is unable to break down and digest the excess fat in many of the modern complete feeds, leading to diarrhea, gas and digestive upset.

Chewing is instrumental to the horse’s digestion because the grinding serves two purposes, to grind the feed down to small particles and to generate salivation. In a horse, salivation is not initiated from smell or taste, but by the physical action of grinding the teeth. For proper digestion and utilization by the hindgut microbes the feedstuffs must be properly chewed and ground down into fine particles. For the horse to achieve suitable grinding dental health must be maintained with proper floating. “Over floating” the teeth will inhibit the horse’s ability to grind. The teeth must have rough opposing surfaces for the horse to be capable of proper grinding – if the teeth are too smooth it would be like trying to grind feedstuffs between two pieces of glass.

The horse’s salivation is also important because it coats and moisturizes the food particles in digestive enzymes to kick start the digestive process and help deliver the particles to the GI tract. Most compound and textured feeds that we are using to replace the natural diet of the horse are “pre-chewed”, meaning that the feed has been ground already. The reduced chewing time restricts the amount of salivation, thus interfering with and bypassing an important part of the horse’s digestion.

Horse Eating

If you do not properly care and provide for your garden at home it will not produce healthy fruit, but only weeds and grass. The same goes for your horse. If you do not feed your horse naturally, the garden within your horse will not provide the proper nutrition your horse needs. This can create health issues for your horse. But, like your garden at home, these weeds can be picked. It is never too late to provide your horse with a natural diet. Remove the fatty foods, the complete feeds, and provide your horse with the diet nature intended it to have. Natural grazing and feeding hay will provide the horse with most of the calories and nutrients the horse needs. Any additional calories needed to maintain body condition should be separated from any additional nutrient intake.  If additional calories are needed, oats, beet pulp, or copra can be fed to meet these increased demands. Proper supplementation with a hay and pasture balancer is also important to replace the nutrients the horse may not be finding in the modern restrained lifestyle. If you have any questions regarding your horse’s diet contact your veterinarian or feel free to contact us at 1-800-624-1873.

Frank Gravlee, DVM, MS, CNS

Scott Gravlee, DVM, CNS

Life Data Labs, Inc.

Makers of Farrier’s Formula® and Barn Bag® Pasture and Hay Balancer

www.lifedatalabs.com