THE LARGE INTESTINE

Most of the nutrient extraction in the horse’s stomach takes place in the large intestine and the cecum where the feed is processed further by bacteria, fungi and unicellular organisms. The chemical processing of the feed is now finished. And the microbiological processing takes over.

The large intestine can be likened to a large ‘sausage’ which takes up nearly 2/3 of the total volume in the abdominal cavity. Here, the content of the stomach remains for up to 3 days while it is being processed by a large number of microorganisms. One single gram of the large intestine content contains as much as one billion microorganisms. These are specialised in different areas such as the production of water-soluble vitamins, amino acids contained in proteins and fatty acids from which energy is derived. It is estimated that up to 60 % of the horse’s body energy is extracted in its large intestine. A large proportion of energy is extracted through the decomposition of cellulose in plant fibres.

The balance of the different types of microorganisms in the large intestine is hugely important as disorders, if any, will affect the general well-being of the horse. Such disorders can for example be caused by inadequate feed rations (e.g. not enough fibres or excess starch), overfeeding, medication, stress or unsuitable drinking water.

Because the horse is designed to eat grass, it is important that most of the energy it needs is extracted in the large intestine – i.e. through the degradation of plant fibres. This creates a balance in the intestinal flora and stabilises bowel function.