The horse’s digestive system is unique and complicated, and mistreating it can lead to a myriad of problems. With the help of our expert, Dr Marion Young, we help you understand how it works and how the various feeds available affect it.
Understanding the basics
Before delving into the complicated labyrinth that makes up the digestive system of the horse, there are a few basic facts that are necessary to grasp.
Horses are monogastric
This means that the stomach is simple and single-chambered.
Horses digest fibre by fermenting it in their hindgut
The horse makes use of ‘hindgut fermentation’ to digest fibre, which should make up the majority of your horse’s daily intake. There is a ‘foregut’, or small intestine, where starch, sugar, proteins and fats are digested, and then the fibre and other undigested items are moved along to the hindgut where bacteria break it down by fermenting it.
The horse has a symbiotic relationship with bacteria
The horse has a mutually beneficial relationship with the bacteria in the hindgut. Long ago, before horses evolved into the creatures we recognise today, they were browsers rather than grazers and they did not have a hindgut or use bacteria to ferment fibre. Circumstances over thousands of years meant a slow evolution into grazers. Foals today eat older horses’ droppings in order to introduce the bacteria into their digestive systems from as early as two weeks old.
The horse is a trickle feeder
Because the horse’s stomach is so small, and because the digestive system cannot cope with too much carbohydrate, fat or protein, the horse should be fed small amounts often rather than large amounts at a time.
Fibre is the most essential ingredient for your horse. Their guts are not designed for high protein, fat and carbohydrate diets.
The digestive system explained
There are two major gastrointestinal regions: the foregut and the hindgut. The system operates as a whole with three aims:
- Digestion of the food coming into the small intestine.
- Fermentation of the structural components of fibre in the hindgut.
- Absorption of the breakdown products.
Digestion in the foregut is supposed to break down the carbohydrates, fats, proteins, unresistant starches and simple sugars. The foregut is divided into three segments and contains enzymes to break the food down so that it can be absorbed into the bloodstream. The foregut, as a rule, cannot break down fibre.
The stomach and foregut cannot break down too much at once and when they are overwhelmed, they will be unable to break down the feed and much of it will pass into the hindgut to be broken down there.
This is bad news for the digestive system as the hindgut is there to break down fibre through fermentation, and when sugar, carbs and fat are digested in large amounts in the hindgut, the fermentation process produces a large amount of gas and other negative by-products causing colic or other gastrointestinal issues.
Text: Peta Daniel
The full issue appears in the April issue of HQ.