Horses have digestive tracts designed for a high fibre diet. The majority of the digestive tract is devoted entirely to the digestion of fibre whereas only a small part is designed to process the starch from oil, protein and cereals. Their hind gut is filled with a bacteria population that processes fibre. These micro-organisms are entirely responsible for digesting fibre as the horse is unable to produce enzymes to deal with the fibre itself. The micro-organisms break down the fibre and also produce ‘volatile fatty acids’ (VFAs).  On a high fibre diet, these VFAs are a weaker acid so the horse’s gut is within a suitable range of acidity. If a high starch and low fibre diet is introduced, the starches from the cereals produce much stronger acids which makes the gut too acidic and problems can occur. Excessive heat and gas may be produced and toxins released which can increase the risk of certain conditions.

Horses only produce saliva when they are chewing; this saliva helps to neutralise the acid produced in the stomach.  Horses are ‘designed’ to chew- feeding small meals of starchy cereal removes this- that’s why it’s so important to ensure fibre intake is always adequate, even with horses receiving high energy diets.

As mentioned, without fibre, a horse’s eating habits can change from constant grazing to a few short meals.  As well as digestive problems, this can lead to boredom and result in bad habits such as cribbing and windsucking.  Although diet is not the only cause of behaviour problems, feeding fibre is always the first suggestion when trying to solve these issues.

Fibre is a slow releasing form of energy, so horses can sustain work for longer periods and those horses requiring stamina will benefit from a high fibre/low in starch diet.