Helen Warren

The equine digestive system and the importance of the hindgut

The digestive process The horse is characterised as a hindgut fermenter because the hindgut is where the majority of the digestive processes take place. Rapid gastric passage through a relatively small stomach and limited intestinal enzymatic digestion, precedes a more prolonged and intense microbial fermentation in the large intestine (Santos et al., 2010). The basic anatomy of the gastrointestinal (GI) tract is similar to that of other non-ruminants with prehension of food and water by the lips and mouth, followed by mastication and insalivation. The resultant food bolus is then swallowed. The stomach is relatively small given the size of the horse with a capacity of only around 8 litres. The stomach also secretes acid continuously, accommodating the nearly continuous grazing lifestyle. Another interesting feature is that the stomach will start to empty into the small intestine (SI) when around two thirds full, irrespective of how long the food has been in situ. The horse is ideally adapted to making use of the ‘wild-type’ or natural diet. Whilst it naturally feeds ‘little and often’ the modern practice of fewer, larger meals, means that food can enter the SI having been subjected to little or no gastric digestion. Once ingesta has entered the small intestine (SI) enzymatic digestion of carbohydrates, proteins and lipids is similar to that of other mammals although the nature of the The equine digestive system inset shows view of the right side to reveal the caecum Large colon Small intestine

Nutrition myths…busted

Four of the UKs top nutritionists collaborate to dispel some of the inaccuracies which abound with regard to the rules and management of feeding horses