Fats in Your Horse's Diet
By Karen Briggs • Aug 09, 2014 • Article #20092
Photo: Anne M. Eberhardt
If there’s a nutritional buzzword for the 21st century, it’s fat. We humans still might not understand fully the differences between saturated and unsaturated fats, let alone “good” cholesterol and “bad” cholesterol—but we all know how to count our fat grams! While we struggle to keep our diets as low-fat as possible, fat has a different focus when it comes to the horse … because only in recent years have we recognized the value of raising the fat levels in an equine athlete’s diet.
Of course, the average human diet (at least in North America) contains far more than the maximum 30% fat recommended for good health. In contrast, the horse’s natural diet contains little fat. While this leaves the horse at low risk for cardiovascular clogging, it does mean that, traditionally, carbohydrates have been considered the obvious and “natural” energy source for performance horses, and fat has rarely been considered beyond that little splash of corn oil that’s considered good for a shiny coat. Only in the past couple of decades have we begun to realize that fat is also a valuable energy source—one with many advantages.
High-fat diets (anything over and above the 2% to 3.5% supplied by a standard grain-plus-forage diet) provide several perks, most notably in terms of energy production for high-level equine performance. Pound for pound, fat supplies almost two and a half times as much energy as the equivalent weight of carbohydrates or starches (traditionally supplied by grains such as oats, corn, or barley). If you wish to supply more energy to your horse without significantly increasing his overall feed intake, supplementing the fat in his diet can be an excellent way to accomplish that.
Also, horses easily metabolize fat despite the fact that their digestive systems (best adapted for the processing of fiber) didn’t really evolve to deal with it. Studies have shown that as much as 20% overall fat in the diet is well tolerated by horses, with no ill effects noted. Indeed, fat might be easier for horses to digest than carbohydrates. It has been demonstrated that a fat-supplemented diet, unlike a high-carbohydrate diet, has no effect on the pH of the cecum (and thus no detrimental effect on the beneficial microflora inhabiting the large intestine). Fat appears to be absorbed almost exclusively in the small intestine.
Another interesting fat digestion fact is that horses can use fats well despite having no gallbladder. In most mammals the gall bladder excretes bile and salts to help break down fats, but in horses the liver seems to take over that function, with no fat digestion problems that research has been able to identify.
Fat-supplemented diets also have been shown to decrease the amount of energy used for heat production in the horse’s body. This decreases the horse’s heat load and increases the amount of energy available for physical activity. In one study, where horses ate a fat-supplemented diet, the horse’s total body heat production decreased by 14%, and the diet had no effect on the amount of energy needed for maintenance metabolism, therefore leaving more energy available for performance requirements (or for energy storage in the form of glycogen or fat). The end result was that more than 60% greater energy was available for physical activity (regardless of what the ambient temperature was or how skinny or plump the horse was at the time).
Some of the most compelling research behind fat demonstrates a fat-supplemented diet’s benefits for high-performance horses (in sports such as three-day eventing, racing, polo, endurance racing, and cutting). But to understand how fat acts as a performance enhancer, we first have to understand some exercise physiology basics. We'll discuss this in an upcoming article.