Feeding the Endurance Horse

Feeding the Endurance Horse


During a race, endurance horses perform prolonged, low-intensity work, fuelled by muscle glycogen as their energy source. Fatigue occurs when muscles become depleted of glycogen stores. Therefore, energy is the most important nutritional component of the diet, and your feeding strategy must reduce the demand on muscle stores of glycogen and supply the energy demands of competition.


According to the National Research Council (NRC), energy demands for working horses are 25 to 100 per cent above their maintenance requirements. But many factors influence an endurance horse's energy requirements, such as the horse's fitness, body weight, training level, rider's weight and skill, environmental factors (temperature, humidity), work duration, terrain, age and muscle fiber composition.


Therefore, the NRC requirements should only be used as a guideline, and you should determine the appropriate feed intake by carefully monitoring your horse's body weight in light of the work he is doing. Below is an example of a well-balanced endurance horse diet.



Forage:The basis of an endurance horse diet should start with high quality forage - hay and/or grass. Horses evolved as grazing animals, continuously eating grass and leaves. Fibrous materials largely bypass the horse's small intestine, for digestion by bacterial fermentation in the large intestine.


Fiber in hay and grass is important for normal function and motility of the horse's digestive tract, and a diet low in fibre can cause colic problems. An additional benefit of feeding hay to the endurance horse, is that the horse will drink more and retain more water prior to the competition. This roughage, water and electrolyte reserve in the horse's large intestine can be drawn upon when needed during the race.


The hay for a competitive horse should be primarily a grass hay. In western Canada, a mid-bloom brome or timothy hay is ideal. Timing of cutting should be early (late June, to early July) to maintain protein quality. Alfalfa hay contains excessive amounts of protein and calcium. The excess protein is inefficiently used for energy and increases the work load of the kidneys.


Feeding excessive amounts of calcium on a regular basis to the endurance horse causes the normal mechanisms for mobilizing calcium stores from the bones to become sluggish. Then during an endurance race, when the horse does need to rapidly replace the calcium lost in sweat, the normal mechanism does not respond adequately and the horse may suffer from the effects of low blood calcium.


So feed an early cut grass hay on a regular basis or keep the endurance horse on good grass pasture, and offer small amounts of alfalfa hay only during the ride when extra calcium is required.


In this sample ration, beet pulp is added as a source of soluble fiber. Beet pulp is available as a dehydrated pellet, which is usually soaked in water and allowed to expand prior to feeding. It can be fed dry without causing digestive upset, but endurance riders prefer to feed it rehydrated as an additional method of getting water into the horse. Beet pulp provides greater energy than the timothy hay and it compliments the water/electrolyte reservoir of fibre.


Most horses will learn to like the sweet taste of beet pulp if you start by adding small amounts of it to the grain ration. The wet beet pulp is also useful to dilute and disguise additions to the ration such as medications, electrolytes and fat.



Grain: With the athletic performance required of endurance racing, a forage-only diet does not meet the horse's energy needs and concentrates must be fed. The quality and quantity of carbohydrates in the diet are important.


Quality carbohydrate sources include balanced grain mixes that contain a blend of energy sources such as oats, barley and corn.


But there are limits on how much carbohydrates a ration should contain for performance horses. If, during a single feeding, excessive carbohydrates are fed, some will bypass digestion by enzymes in the samll intestine and will reach the horse's large intestine. In the large intestine, carbohydrates are digested by the bacterial flora, resulting in an abundance of lactic acid and gas production.


Lactic acid lowers the PH of the large intestine and alters the normal bacterial flora, and along with the gas, may cause colic. Therefore, the grain portion of an endurance horse's diet should be split into as many small portions as possible over the day to maximize digestion in the small intestine.


Another caution in feeding concentrates prior to a race is the potential for insulin rebound. Rapid absorption of sugars from a high carbohydrate meal will cause a large surge of insulin about 90 minutes post-meal. This excessive insulin release can cause blood sugar levels to drop precipitously. To prevent this hypoglycaemia from occurring during the race, concentrates need to be fed at least three to four hours prior to the start, and then small amounts are fed at frequent intervals during the race.


Glycogen loading, a dietary protocol used by human athletes who eat large pasta meals before a competition, does not seem to be an effective way of generating energy reserves for endurance horses. Horses naturally have higher muscle glycogen levels than humans, so there is less potential for super-compensation in horses. In addition, it is difficult to feed large amounts of highly digestible carbohydrates to horses without causing colic and laminitis.



Fat: One of the most recent developments in the feeding of equine athletes is the addition of fat to the diet. Fat contains more energy than an equal weight of carbohydrates. Because fat increases the energy density of the diet, the total feed intake needed will be less to meet the endurance horse's demands.


Fat also appears to preserve glycogen stores longer and moderates the insulin surge and rebound hypoglycaemia seen with feeding carbohydrates during endurance exercise. High fat - low carbohydrate diets reduce the incidence and severity of exertional rhabdomyolysis (tying up) in some horses.


Commercial horse feeds contain only small amounts of fat, usually less than three percent. Fat can be slowly added to the concentrate portion of the horse's diet up to 10 per cent. Horses require up to 21 days to adjust to a fat-supplemented diet. Adding fat to the diet on the day of the race is of limited benefit.


There are commercial horse feeds available that contain added fat, but there are advantages to top-dressing the fat. When you top dress the feed with corn or canola oil, you can manipulate the energy portion of your horse's diet easily. For example, if the horse's energy demands are reduced temporarily, you can easily cut back on the amount of fat added. Also, purchasing corn or canola oil in large quantities and top-dressing is less expensive than a high fat commercial feed.


Feeding fat also increases the palatability of the feed, helps with the absorption of vitamin A and vitamin D, provides essential fatty acids that improve skin and haircoat, and it controls dust and fines in feed; however, corn and canola oil can easily become rancid. So bulk supplies should be stored in a cool place and kept in a tightly closed container to reduce oxidation. Even though it may smell fine to you, if your horse starts refusing feed with added fat, then the oil is likely to have become rancid.



Additional Supplements: There are numerous supplements available for performance horses. These supplements are most appropriately used to correct some specific deficiency or imbalance in a horse's diet. If you feed a commercially-formulated horse feed and good quality hay or pasture, it is highly unlikely that your horse's diet will be deficient in vitamins or minerals. Owners and trainers like to feed supplements as 'insurance' for optimum athletic performance. Over-supplementing is usually harmless and merely a waste of money. But in some cases an excessive amount of nutrient may cause toxicity and decrease performance.



Zwann Farm Feeding Strategy: We offer our horses high quality grass/alfalfa hay at all times at a ride. If they will eat it wet, we soak the hay in order to get any extra water into them. We feed a normal grain/beet pulp/canola oil feeding the evening before the race. One of us gets the early morning wake up call, to offer a small meal of predominantly beet pulp (with some grain and oil) about three hours before the start time.


At vet checks, we continue to offer free choice hay and small amounts of a sloppy mash of beet pulp and some grain. We take advantage of any good grass at any check point.


After the race, we allow the horses several hours to drink and fill up on hay, then usually split the regular evening ration into two portions, giving the first about dinner time and the second before we call it a night!



This article was written by Dr. Trisha Dowling
She was CaLDRA's secretary for 2001
I have copied it from the Spring 1999 issue of
Going the Distance, CaLDRA's newsletter.
They reprinted from Horses All

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