Horses have evolved on high fibre diets, and should be fed a minimum of 1% of their body weight per day in fibrous feeds. Fibre has many important roles in horse heath. It is a source of energy, provides the horse with gut fill (bulk), horses spend more time chewing the fibrous feed, so they produce more saliva which buffers the stomach and protects it from ulceration, and the fermentation of fibre also produces B vitamins. 

 

It is known that grain based diets are often responsible for causing ‘fizzy’ or stereotypical behaviour, gastric ulcers, tying up, laminitis, and colic. Horses have a limited ability to efficiently digest the large amounts of starch present in grain based diets due to limited enzymes in the small intestine. When excess grain is consumed, it will escape digestion in the small intestine and overflow into the hindgut where it is rapidly fermented into lactic acid. The build up of lactic acid causes a decline in faecal pH, killing the good bacteria and releasing endotoxins in the blood, often resulting in metabolic conditions and digestive upsets.