Why Do Some Feeds Make Our Horses Sick?

Why Do Some Feeds Make Our Horses Sick?

Have you ever wondered why it is that what we feed our horses can so easily and so often make them sick or change their behaviour? Many common equine diseases and problems including colic, tying-up, laminitis, cushing?s syndrome, acidosis, poor appetite, unruly behaviour, poor performance and developmental orthopaedic diseases are all caused by, exacerbated by or can be linked back somehow to what we are feeding our horses.

Why is what we feed causing disease?
We can find at least some of the answers to this question when we look at what horses eat in their natural environment and what we feed our horses in their somewhat artificial, domesticated environment. First we must ask ourselves, how is what a horse eats in it natural environment different to what a horse eat in a closely managed domesticated environment different? Let?s start to unravel the answers by taking a look at the horse?s evolution.

From four toes, to one ?
Millions of years ago, the horse is thought to have been a dog sized animal with 4 toes. This small creature, named Hyracotherium was primarily a browser and lived within a protected forest environment. As climatic changes took place, many of the worlds forests where Hyracotherium lived were replaced by savannah and grass lands. These environmental changes meant Hyracotherium was faced with having to eat a diet of low energy, high fibre grasses (which was distinctly different to their somewhat succulent diet they consumed as a browser) and without the protection of the forest they also became easy targets for larger predators. These changes forced Hyracotherium to increase in size. The equids increasing size meant increased speed, which allowed the prehistoric horse to outrun its predators. It also meant that the gut was able to enlarge and incorporate the sizeable fermentation chamber we now call the hindgut, whose primary function was, and still is to house billions of bacteria who ferment and extract energy from fibrous plants such as the grasses the horse was now being forced to live on. The hindguts capacity to ferment and extract energy from grass, in combination with the horse?s ability to consume large amounts of forage in a day meant that horses had placed themselves within an environmental niche where not even the ruminants were able to compete. Consequently the horse remained and developed into the large, grazing, single hooved animal we know them as today (Budiansky, 1998).

What do we know about a horses ?natural? diet and grazing behaviour?
Equines in their natural environment are opportunistic feeders, and will consume whatever is available to them and edible at the time. The modern day horse is primarily a grazer and prefers grasses and grass-like forages, but they will still occasionally browse trees and shrubs. A study conducted in Western Alberta found that 93% of a horse?s diet consisted of grasses and grass-like species. The remaining 7% of the diet was made up of forbs, browse and other miscellaneous species such as lichen and moss. In total, these horses were consuming up to 43 different plant species throughout the year. Similar studies conducted in Colorado and New Mexico also found that a horse?s diet was highly varied, but was based on grass and grass-like species. It can be assumed that horses, during their time grazing grasses would have eaten some seed heads and grains. However, it can also be assumed that due to a horse?s tendency to graze the green, more succulent parts of plants which are higher in energy, seeds and grains did not make up a significant part of the natural diet. In addition, the modern day starchy cereal grains that have been genetically selected and developed for use in the human diet almost certainly did not feature as part of the equids natural diet.

With respect to grazing habits, it is known that horses in their natural environment spend large amounts of time grazing. Studies of wild horses estimate that equids will spend from 50% to 75% of a 24 hour period consuming food (Duncan, 1980; Tyler 1972; Salter et al. 1979; Keiper et al. 1980).

How has the domestication of the horse changed their diet and grazing behaviour?
Horses were domesticated by humans less than 6000 years ago. Upon domestication, horses became an indispensable means of human transport. They were also used for heavy haulage and farm work. While some horses are still used for work their place in western society has changed dramatically, with their main uses now being focussed around sport, competition and pleasure. Regardless of their use or purpose, the horse?s diet has been changed significantly.

Consider for a moment, where horses in their natural environment roam free, we now keep them confined to box stalls, corrals or small pastures, which dramatically restricts their ability to select their own feed throughout the day. We tend to feed our horses a relatively plain diet, consisting of perhaps one or two types of forage and hard feeds that may contain up to ten different seeds or grains, many of which are high starch cereal grains. For convenience reasons, we also commonly feed horses a small number of large meals each day. So domesticated horses now consume a diet containing less than 15 different species of plants (compared to the natural diet which may contain 40+ species of plants), we have added starchy cereal grains, which were not originally part of the natural diet and we have changed the pattern of eating from continuous intake to large meals. 

So why did we make such dramatic changes to their diets? Aside from the convenience factor, horsemen realised that the use of the horse for work, sport, competition and breeding altered and generally increased their nutrient requirements.

Meeting the domestic horse?s nutrient requirements ?
Recognising that a working or breeding horse had an increased need for energy, early horsemen began feeding starchy cereal grains. Grains were chosen because they were cheap, readily available and palatable for the horse. What these horsemen didn?t know was that, because the modern day high starch cereal grains had not been a part of the horse?s natural diet, horses were not well equipped to digest and utilise them. While horses have some capacity to digest the starch from cereal grains, this capacity can be easily exceeded. Researchers from the Texas A&M University estimate that horses are capable of digesting 3.5 ? 4 grams of starch per kg bodyweight/meal (0.05 ? 0.06 oz/lb bodyweight). Beyond this point it is believed that starch overload into the hindgut will occur, causing problems such as hindgut acidosis, colic, laminitis and altered behaviour. Nutrition texts from mid last century mention that horses will become ?food-sick? or colic when fed wheat in an uncontrolled manner. It was also noted that grain feeding could cause ?crippling laminitis, digestive disturbances and kidney disorders?. ?Monday Morning Disease?, now identified as tying up was also commonly reported in horse?s that were fed grain based diets.
So it has been well known for some time that the addition of cereal grains to a horse?s diet can cause several debilitating diseases. The simple answer to preventing these diseases would be to simply remove cereal grains from the diet. However, grains were added to help meet the elevated energy demands of working horses. If they were simply removed from the diet, working horses would quickly begin to lose weight and their performance standards would fall. So, we are left with somewhat of a feeding dilemma. Working horses need to have their energy requirements met, however, meeting them using cereal grains can cause diseases and poor performance.

The question therefore, is how do we meet a working horse?s requirements for energy without overfeeding cereal grains? The answer is: by feeding high energy fibres and oils. Because fibre made up such a large component of a horses diet in their natural environment, they are well equipped to digest and extract energy from it. Likewise, oils have always been present in a horses diet (as grasses are typically 2 ? 3% oil) and thus horses appear to be well equipped to digest oils, even when fed in relatively large quantities of up to 20% of the diets total energy.

New generation feeds

The sugars and starch in feeds is termed the Non Structural Carbohydrates (NSC).  It is believed that feeds containing more than 12% NSC are a major cause of the disease and poor performance of many horses.  Some so called cool feeds contain up to more than 40% NSC. The opportunity therefore is to feed high energy, low NSC feeds.

Copra Meal is a natural, high energy, high fibre, low NSC  feed that provides a palatable, safe alternative to cereal grains in the diet of working horses.  Copra Meal allows you to meet the horses energy requirements without causing the problems typically associated with high NSC diets.