Equine Nutrition in the 21st Century, Part Three
Confused about the best energy sources for your horse? Here is another installment in the award-winning series from equine nutrition expert Judy Reynolds, Ph.D., P.A.S., Divisional Equine Technical Specialist, ADM Alliance Nutrition.

Traditional horse feeding programs are based on some misconceptions about horse feeds. For instance, horses need a certain amount of energy-producing nutrients from their rations (Table 1), but hays and pasture can and should provide most of that energy.

Table 1. General Digestible Energy (DE) Requirements of Horses adapted from NRC, 1989

Unfortunately, many people have the misconception that energy must come from grains. In fact, of the four categories of horse feeds, grains are a poor second to fats and provide only slightly more energy per pound than fermentable fibers (like soybean hulls and beet pulp) and good-quality hays (Table 2). This means that grains supply only 35% as much energy as fats, 108% as much as fermentable fibers and 128% as much as good-quality hays. However, corn and barley provide even less energy when they are not processed, due to their low pre-cecal starch digestibility.

Table 2. Digestible Energy Content of Horse Feeds, adapted from NRC, 1989 and other sources

Fortunately, feeds in all three of the non-grain categories are easily digested by horses and, therefore, are safer to feed. Sticking to these feeds results in very few metabolic problems. Feeding grains is more risky depending on the type of grain fed and the amount of processing of the grain (see Part 2 - All Grains Are Not Created Equal). If most of the grain starch in a ration is digested in the foregut (for example, oat starch), the only problem is a potential 'grain-high' attitude. But, if much starch enters the second part of the tract where the fiber-digesting bacteria live (for example, corn and barley starch), there might be severe consequences for the horse. The starch is rapidly fermented, by starch-digesting bacteria, resulting in a more acidic cecal environment. Under those conditions, bacteria that should digest the fiber die and release toxins or poisons that can result in colic and founder.

So, how should we provide energy to our horses?

We should start with forage. This means pasture or at least 20# of good-quality hay every day for an average-sized mature horse. This pasture or hay should be chosen to meet as much as possible of your horse's protein, energy and fiber needs. The most important thing here is to select the right forage for your horse. Then you should add vitamins, minerals, fats and limited amounts of grains (up to 6 lb/day) as needed (Table 3).

Fats and oils can be fed at up to 10% of the total ration. Horses fed fats are less likely to suffer from digestive and metabolic disorders, such as colic, founder, tying-up and gastric ulcers than horses fed large amounts of grains. Vegetable oils (corn, soybean) and food-grade stabilized rice bran (20% fat) are efficiently digested by horses and are excellent sources of energy. Oils are easier to digest when supplied as part of a grain mix or pelleted feed than when top-dressed over feed. Stabilized rice bran is very digestible and can be top-dressed or mixed into grains or pelleted feeds.

Table 3. Digestible Energy (DE) Percent Provided Per Feed Category in Forage-Based Rations

Modern feeds contain added fat and digestible fiber, so they have less grain and starch than older formulas contained. For example, some feeds with varying fat, digestible fiber and starch concentrations are contained in Table 4.

Table 4. Nutrient content of traditional vs. modern feeds

In conclusion, the majority of the DE in horse rations should come from forages. It is important to choose the correct forage and feed the correct amount for each horse. When additional energy is needed, it is safer to use fats and fermentable fibers before grains. Fortified, grain-based feeds can usually be used at up to about 6 lbs per horse daily (3 lbs per meal) without digestive problems. However, modern feeds with added fat and digestible fiber are recommended over high-starch feeds.

Next Page
Part 4 - A New Look at Fiber in Horse Feeds

Quick Tips

1. Meet most or all of your horse's energy requirement with forages
2. Limit grain-based feeds to 3 pounds per meal
3. Look for feeds with at least 12% crude fiber and soybean hulls, beet pulp and/or alfalfa on the label
4. If you need a high-energy feed, choose one with more than 5% fat from vegetable sources
5. To increase the energy content of any ration, supplement with food-grade stabilized rice bran