Wednesday 16th of September 2020

Understanding how the equine digestive system works

As all horse owners know, the horse is a herbivore. More specifically we describe the horse as a non-ruminant herbivore as it has a small, simple single compartment stomach.

The horses’ stomach is also relatively small and suited to constant slow intake of forage as opposed to large meals of concentrated energy such as cereals. The horse also has a psychological need to chew. Chewing also causes a continuous release of saliva which helps to buffer stomach acid.

But what does it mean to be a large herbivore? In the first place, plants that horses eat in the wild are generally low in energy. This means that in order to obtain sufficient energy, horses typically need to spend at least around 12h a day eating and in some cases, up to 18h. 

When it comes to what horses eat, there is a big difference between domesticated horses and wild horses. Whilst the wild horse is predominantly a grazer, they will generally be grazing grasses that are low to moderate in protein, low in starch and of low-moderate digestibility. But they may be grazing a large variety of species of grass. In addition, wild horses will also browse many other plants.

In contrast, the domesticated horse is often grazed or fed more highly digestible grass or forages with higher protein and energy. At the same time, the domesticated horse usually does not have the opportunity to browse other vegetation. For this reason, whilst wild horses may achieve a balanced or adequate nutrient intake, the domesticated horse that is on a forage only diet will almost certainly not be receiving a balanced or adequate intake of nutrients.

The two major digestive problems that we most commonly observe in horses are gastric ulcers and colic. Both of these are often related to nutrition. So, what are some basic guidelines for minimising the risk of digestive problems in horses? The horse has a physical and psychological need for good quality forage. Whilst low quality forage such as straw or poor hay may be seen as an option for weight reduction, this can lead to other digestive problems. Hay or haylage should also be of a high level of hygiene with minimal dust and micro-organisms (yeast, bacteria, fungi, etc). This is also critical for good respiratory health and high temperature steaming is an excellent option to better ensure good hygiene and minimise the risk of respiratory disease. Where possible providing ad libitum forage will also reduce the risk of digestive problems.

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