Feeding horses with Equine Metabolic Syndrome (EMS)
A rider’s worst fear is arriving at the stable one morning and finding the competition horse that has been training well and seemingly in good health is now showing signs of extreme soreness in its front feet. The veterinarian performs the necessary diagnostics and determines the horse has a very mild case of laminitis. How could this occur? The horse’s diet hasn’t changed, it’s not excessively overweight nor has its training regime been changed. Unfortunately, laminitis is a condition that can occur for many different reasons with one potential cause being sensitivity to sugar and starch in the diet resulting in insulin resistance and ultimately laminitis. If the horse is a competition horse, this situation raises the question of how it can be fed to maintain performance and prevent the reoccurrence of the disease. There is a lack of information available for feeding and management strategies for horses suffering from Equine Metabolic Syndrome (EMS), such as obesity, laminitis or insulin resistance. There is even less information available for feeding horses that were previously affected and are now returning back to work. To understand what to do nutritionally, it is important to start at the beginning. The horse, a non-ruminant herbivore, is well suited to a high-carbohydrate diet consisting predominantly of plant forages. Plant carbohydrates in equine feeds can be divided into: structural carbohydrates (SC), which largely make up the fibrous portion of the diet and originate from the plant cell wall, and the nonstructural carbohydrates(NSC) – sugar and starch (NSC), which originate from inside the plant cells. Together, the NSC and SC constitute the main energy-yielding portions of the horse’s diet. The desire to have horses perform under saddle elevates their requirement for energy and necessitates the use of higher carbohydrate feeds. Specifically, performance horses are often fed cereal grains with high NSC (sugar and starch) content. Sugar and starch provide fuel for performance that is quicker and metabolically more efficient than structural carbohydrates. Sugar and starch are rapidly broken down in the horses’ small intestine while structural carbohydrates must be fermented by bacteria in the horses’ large intestine. For this reason, this quick and efficient fuel, such as oats, corn and barley are important for performance horses. Unfortunately, the consumption of sugar and starch-rich meals may increase equine digestive and metabolic disorders linked with carbohydrate metabolism. The common practice of feeding sugar and starch-rich cereal grains with high glycaemic indices may promote insulin resistance in horses and ultimately lead to laminitis.
Insulin Resistance (IR) is becoming more common in horses. IR is a disease in which tissues (muscle and liver) have become resistant to the affect of insulin, the hormone that facilitates the uptake of glucose from the blood into the tissues of the body. When a horse becomes resistant to insulin, they must produce more insulin to clear the blood of glucose. Horses with IR have chronically high levels of insulin and often have high levels of blood glucose which can have damaging consequences for circulation and is thought to potentially facilitate laminitis. HYGAIN® Feeds offers two forage-based low starch feeds completed with vitamins and minerals: HYGAIN ZERO® and HYGAIN® ICE®. HYGAIN ICE is designed for ponies in work prone to metabolic related disorders, maximizing performance while keeping them calm and cool. HYGAIN® ZERO® is a unique Low Carb - Low GI feed for all horses, with less than 1.5% starch, less than 5.5% non structural carbohydrates (NSC) and absolutely no grain or grain by-products. HYGAIN® ZERO® was developed to support the specialised dietary requirements of horses and ponies with conditions such as Obesity, Insulin Resistance, Laminitis, Cushings, Tying-Up or Grain Intolerance. The unique Low Carb – Low GI profile however is suitable for any equine requiring a low sugar and starch diet. While low carbohydrate feeds (low GI), such as vegetable oils, beet pulp and lucerne chaff, provide an alternative energy source for horses sensitive to starch with a history of digestive and metabolic disorders. Exercising horses require some dietary sugar and starch in order to provide enough energy to fuel performance. Sugar and starch are broken down and metabolized almost twice as fast to generate ATP for muscle contraction. So any speed work or jumping effort that requires explosive muscle contraction will benefit from sugar and starch in the diet.
Feeding and Management StrategiesThere are many scientific studies describing feeding and management strategies for horses suffering from metabolic syndrome, such as obesity, laminitis or insulin resistance. However, there is a lack of information available for nutrition and management strategies of those horses that recovered from laminitis or have a sensitivity to sugars and starches and that are now returning to competition. These horses are difficult to manage because calories must be provided for weight maintenance or gain, without causing a relapse of metabolic syndrome or laminitis. This becomes even more important when horses are exercising and using more calories. Feeding recommendations should therefore be tailored to the individual horse. The following guidelines should serve as a starting point.
Ideally, feeding strategies for horses kept under intensive conditions would mimic the pattern of a grazing animal. For stabled horses, foraging (grazing) behaviour should be encouraged by increasing the availability of hay (or even a variety of different forages) and pasture. Provision of more frequent and smaller concentrate meals throughout the day is also recommended (e.g. three times a day rather than twice a day). Extending eating time by diluting the energy density of the meal (e.g. chaff mixed with concentrates) or feeding forage such as hay, HYGAIN FIBRESSENTIAL or HYGAIN MICRBEET before grain or concentrate may be helpful.
For hard working horses with high DE requirements, the provision of roughage is often restricted in favour of grain concentrates to ensure adequate energy. However, there is considerable evidence associating low roughage diets with digestive disturbances (e.g. hindgut acidosis, colic, gastric ulcers) and behavioural problems. A minimum amount of roughage ranging from 1 to 1.5 % of body weight (BW) has been recommended (e.g. 500 kg horse = 5 – 7.5 kg roughage). It is difficult to determine the sugar content of hay without having it analysed. There are many different environmental conditions that can alter sugar accumulation in hay, for this reason if you have a horse currently suffering from a metabolic disorder it would be prudent to have the hay analysed to determine actual sugar content. Alternatively, fibre intake can be increased by feeding other sources of roughage such as sugar beet (HYGAIN MICRBEET) pulp or HYGAIN FIBRESSENTIAL nutritionally enhanced chaff nuggets, all of which are highly digestible fibre sources. This approach also helps to decrease the reliance on grain or sweet feed for energy, thereby decreasing risk of digestive disturbances associated with high starch intake. So called “super fibres” contain a large component of digestible fibre and levels of non-digestible fibre, which means more fibre available for microbial digestion. Super fibres contain digestible energy equivalent to oats while not while not producing symptoms of grain overload.
Grain concentrate considerations
- Size of grain-concentrate meals: The feeding of large meals rich in starch and sugar can overwhelm the digestive capacity of the small intestine and upset the microbial population of the hindgut. No more than 2 kg of grain or sweet feed mix should be fed in a single meal (500 kg horse).
- Feed starch sources with high digestibility: Starch digestibility varies with the type of grain and the nature of any mechanical or thermal processing. Milling, grinding, and various heat treatments (e.g. steam flaking, micronization, extrusion) improves the starch digestibility of oats, barley and corn. Heat micronization substantially increases the starch digestibility of corn and barley. Overall, oats appear to be the safest source of starch for horses.
- Use alternative sources of energy: The energy demands of performance can be readily met by provision of alternative energy sources such as vegetable oil (fat) and non-starch carbohydrates (e.g. MICRBEET, soya hulls). Commercial concentrates made with these ingredients will contain varying amounts of starch and sugar, but in general amounts will be substantially lower when compared to straight cereals or sweet feed mixes. When compared to more traditional fiber sources like hay, soy hulls and beet pulp contain lower indigestible material (e.g. lignin) and higher amounts digestible fibers which translates to a higher energy yield. It is recommended to feed up to 75-100 g oil per 100 kg bodyweight/day. This daily amount should be divided into 2-3 meals and introduced gradually (e.g. starting at 50 ml/day).
There is considerable interest in the use of feed additives such as live yeast culture, and bacterial species as a strategy to minimize the negative effects of cereal-based diets. Yeast cultures might be beneficial for stabilization of the hindgut environment, when high cereal diets are fed.
Dietary therapy alone may not be sufficient to reverse insulin resistance. Research has shown that both obese and lean horses had improved insulin sensitivity after seven days of moderate exercise training. Exercising your horse is beneficial; however you should first consult your veterinarian to develop an appropriate exercise regime.
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