Keeping your horse’s gut health
Professor Jo-Anne Murray
PhD, MSc, PgDip, BSc (Hons), BHSII, RNutr, PFHEA University of Glasgow Veterinary School
Natural diet of the horse
Horses have evolved to browse and graze, are well suited to high-fibre, low-starch diets, and spend 16-18 hours per day grazing. Wild horses rarely fast for more than a couple of hours at a time. The dietary management of domestic horses is often far removed from that of their wild counterparts. If we consider how we typically manage the domesticated horse, they are often stabled for many hours of the day and can be fed meals containing concentrated energy sources, such as cereal grains, which are high in starch. Providing horses with forage on an almost continual basis not only provides digestive benefits, but it also meets their behavioural needs and this is important to promote good welfare. The domestic horse’s wild counterparts would spend a great deal of time searching for and consuming food.
In contrast, domestic horses often have limited opportunities to forage and it can be the case that the fibre component of the diet is also restricted. Consequently, this can impact on gastrointestinal health. The horse is classified anatomically as a non-ruminant herbivore and has a digestive tract that consists of three functional regions; the stomach and the small intestine, collectively termed the foregut, and the large intestine, often referred to as the hindgut. Starches, sugars, lipids and protein are digested in the foregut, whereas the fibrous components of the diet (non-structural carbohydrates) undergo microbial fermentation in the large intestine as the horse lacks the endogenous enzymes required to digest these plant constituents.
Diet and gut health
An association between diet and gastrointestinal health is widely recognised. Many dietary factors can affect the health of the equine digestive system, including diet composition, meal size and changes in dietary management. An adequate supply of forage in the diet of the horse is essential in maintaining both gut health and satisfying the behavioural needs of an animal that is intended to eat on an almost continual basis. Forages should therefore form the basis of all rations since this is the most logical and economical approach to feeding horses. In fact, the National Research Council, 2007 recommendations for maintaining gut health and integrity are 1 kg dry matter (DM) forage per 100 kg of liveweight; therefore in a 500 kg horse with an appetite of 2 % bodyweight, the amount of forage fed should be no less than 5 kg dry matter.
The problem is that the nutritional requirements of many sports horses cannot be met by the high bulk, low-energy forage diets of their forebears, for which their alimentary canal was designed. As such there has been a need to include more energy-dense feedstuffs in the diet to meet the energy requirements of horses with higher energy requirements. This has generally been achieved through the incorporation of cereal grains into the diet, with energy intakes