The Horse's Digestive System

Bishop Burton College Equine Science lecturer Georgina Smith talks to us about the Equine Digestive System to help us better understand how we feed our horses.

Baillie Haylage have partnered up with the Equine Nutrition experts at Bishop Burton College to provide horse owners with quality feeding advice. Georgina Smith BSc (Hons) MRes explains how important it is to understand the Horse's Digestive System and how grass forage can maximise welfare and performance.


Horses have evolved over millions of years to become specialised in their digestive ability. As their habitat changed from trees and bushes to expanses of flat grassland, their feet evolved to gallop and their teeth evolved to graze and grind.

Horses will graze for around 16-20 hours a day, meaning the equine digestive system has adapted to work best when the horse is trickle feeding (eating little and often).

As they have evolved to eat grasses, the gut has evolved to digest these efficiently and maximise energy gained from them.

As the grass passes through the horses digestive system...

  • The small intestine breaks down and absorbs important nutrients such as proteins, sugars and fats.
  • This leaves the bulk of the grass (fibre) in the hindgut, where it ferments for use as the horse’s primary energy source.

This system is so specialised, we need to make sure our horses are continually fed we continue feeding our horses sufficient fibre at consistent points during the day to enable the digestive system to function at its best and avoid any nutritional disorders.

The Digestive Process Starts In The Mouth

The digestive health benefits of a high fibre diet begin with the mouth.

Horses are hypsodont, meaning that their teeth grow continuously throughout their life. This is why routine appointments with an equine dentist are so important. We can encourage by feeding plenty of fibrous forages, such as haylage, horses can naturally grind their teeth down.

These tougher materials maximise the horses jaw range of motion, encourage an even wearing of the teeth, therefore avoiding issues such as hooks on the teeth.

A continuous supply of forage also encourages saliva production. This is to keep food lubricated and provide a small buffering action in the stomach, which helps reduce the likelihood of gastric ulcers and general stomach discomfort.

Trickle Feeding

Trickle feeding encourages movement through the gastrointestinal tract called ‘peristalsis’. This is highly important to keep continuous flow through to the hindgut. Issues with this movement can lead to conditions such as impaction or tympanic colic.

In mild cases, the horse may be uncomfortable for a while before resolving itself, however colic often needs immediate veterinary attention. Therefore it is of the utmost importance that owners provide an adequate supply of forage to keep peristaltic motion. Advice recommends that we feed no less than 1.5% of the horse’s bodyweight in forage per day (in addition to any hard feeds).

The Equine Hindgut

Finally, as described earlier, the equine hindgut is highly specialised for the fermentation of fibre. This is largely down to the populations of microbes in the hindgut. These populations should be diverse and fibre-focused which is achieved by a high forage diet.

The golden rules for encouraging a healthy hindgut include...

  • making any changes to the diet very slowly (so as not to upset the delicate balance of microbes)
  • avoiding feeds that are very high in starches and sugars, (recommended to be no more than 1g per kg of horse’s bodyweight per meal). Too much starch can cause feed to be ‘dumped’ in the hindgut. The microbes will rapidly ferment this and produce excess acid which can disrupt the environment.

Overall, the horse's digestive system has taken millions of years to adapt to a 100% forage diet. It could take millions of years for the horse’s system to evolve further to cope with domestic diets!

By maximising forage in their diet, providing constant fibre and by limiting starch proportions, you can optimise your horse’s digestive health and maximise welfare and performance.

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Keeping horses feeling and looking well, whilst providing just the right energy for work is a balancing act. We have a comprehensive feeding guide and are always happy to discuss any aspect of your horses’ diet and management, helping you to select which haylage type is best for your horse.

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