Article and Photos by Bridget Cook

Most of us have dribbled a bit of oil on our horse’s feed at one time or another. We’ve scoured the aisles at the feed store looking for a wonder oil to make our horses fat and shiny, and we’ve also heard it told that a horse shouldn’t even consume fat.

Fat is a naturally occurring component of feedstuffs, including forage. Used correctly and for the right purposes, fat can make our horses look better and perform better. In fact, Dr. Larry Lawrence, senior nutritionist at noted independent equine research and consulting facility, Kentucky Equine Research in Versailles, says that fat is one of the most important parts of the equine diet.

Increasing Caloric Density

fat oats web

A horse gets the same amount of energy from 1 pound of fat as it does from 3 pounds of oats.

The main reason horses are fed high-fat diets is to increase the energy going into the horse. This may be done because the horse burns more energy than it is being fed or to increase the horse’s weight.

“If we look at the amount of energy we can get from carbohydrates and proteins and compare that to fats, we can get about 2.25 times more energy from fat than we can from an equal amount of carbohydrate or protein,” says Dr. Larry Lawrence, the senior nutritionist with Kentucky Equine Research. “In a practical sense, 1 pound of fat is equal to about 3 pounds of oats in terms of energy. Similarly, 2.5 pounds of corn is equal to 1 pound of fat.

Feeding a horse more than 5 pounds of grain per feeding can disrupt the normal microbial balance in the hindgut because some grain will escape digestion and get into the hindgut. This may eventually lead to colic or laminitis. Therefore, horses with very high-energy requirements can reduce the amount of grain they need to eat with the use of supplemental fats.

“You can reduce the amount of grain that’s going into the horse and increase the amount of calories,” Lawrence says. “We’re trying to cut back on the amount of starch and sugar from the grains, i.e. corn, oats and barley but still keep up the high energy for the horses that need it.

“That’s very important when we look at high-performance horses, for example, racehorses that are eating 15-18 pounds of grain a day. That’s phenomenal, and no one should ever feed their horse that much grain, and most fairly intense performance horses wouldn’t eat half of that amount of grain. If we add fat to the ration, we can feed the horse less grain and still keep up the energy consumed.”

Other Benefits
High-fat diets have been shown to improve the behavior of the horse in addition to contributing to a glossy hair coat. Behaviorally, the physiological reason has not yet been discovered, however, evidence in the field has shown that replacing calories that the horse receives from grain with calories from fat will aid in producing a calmer, more focused horse.

It is thought that fat can be secreted from glands in the skin to coat the hair shaft. This fatty coating protects the hair from the effects of the sun and weather and makes the hair look shinier.

Polysaccharide storage myopathy (PSSM) is a common genetic disorder in Quarter Horses. These horses store large amounts of glycogen in the muscle, however, the glycogen has an abnormal structure and is difficult for the horse to use.

PSSM horses often display symptoms similar to tying up; their muscles will become very tense and they make even start to shake.

High fat, low starch diets offer a helpful method of treating PSSM horses.

Fat Sources
Some fat occurs naturally in the horse’s diet. All the grains—corn, oats and barley—contain approximately three percent fat, while forages contain between two and six percent fat.

Fat contains fatty acids, with the two most influential types of fatty acids being the Omega-3’s and Omega-6’s. While they are both essential to animals, Omega-3’s are preferred, as they produce less-inflammatory agents than the Omega-6’s.

Forage is higher in Omega-3 than Omega-6, so when supplementing fat in a horse’s diet, the Omega-6 to Omega-3 ratio of the fat should be considered. The higher the level of Omega-3’s, the more preferable the fat. Fat supplements should remain within an Omega-6 to Omega-3 ratio range of 4:1 to 7:1.

“The reason for that is the Omega-6’s and Omega-3’s compete with one another,” Lawrence says, “and if we get high Omega-6’s, then we get high pro-inflammatory agents versus the less-inflammatory agents derived from Omega-3 fatty acids.”

Two examples of common Omega-3 fatty acids are Eicosapentaenoic acid (EPA) and Docoshexaenoic acid (DHA). They are considered to be less inflammatory and healthier for the horse.

“These two fatty acids are less-inflammatory,” he says, “so they have an effect on inflammation of the joints, inflammation of the lungs, and they make blood cells more pliable and less fragile, which is important for a performance horse whose blood cells are able to deliver oxygen well without problems.”

Vegetable oils, such as soybean, corn and flaxseed, are the most commonly used oils for horse consumption.

“Vegetable fats are 95 percent digestible in the horse,” Lawrence says, “and almost all of it would be digested and absorbed in the small intestine, so it doesn’t reach the hindgut. When we’re making feed and adding oil to feed, we are generally adding soybean oil because it has a better Omega-6 to Omega-3 ratio. The ratio of soy oil is approximately 7:1, whereas the Omega-6 to Omega-3 ratio in corn oil is about 57:1, so we try not to use as much corn oil as we once did in the past to improve the Omega-6 to Omega-3 ratio.”

Canola is also a good source of fat and has an Omega-6 to Omega-3 ratio of 2:1.

One of the disadvantages of the Omega-3’s is that they are highly reactive and can go rancid very quickly. Commercially produced oils are stabilized, so they can be stored easily. Often the stabilizer used is the antioxidant vitamin E, which also has positive effects for the horse.

Corn oil is known for helping create beautiful hair coats; however, its high Omega-6 content makes it a less-desirable, supplemental oil. Instead, soybean oil and flaxseed oil, which is very high in Omega-3, can be used to promote healthy coats. Flaxseed oil is derived from flaxseed (tiny, hard black seeds). If feed is top dressed with actual flaxseeds, the horse will not realize the benefits of the Omega-3 fatty acids.

“If you just put flaxseed in with the horse feed, a lot of those seeds are not going to get ground up by the teeth, so it is not effective,” Lawrence says. “Some people will grind the seeds themselves, and that’s not a great way to go because you haven’t stabilized the fat. Typically, the best way to feed flaxseed is to buy a ground flaxseed that has been milled in a way that it has been stabilized and protected so it doesn’t go rancid. If you grind it yourself, you don’t get the full effect of the Omega-3’s like you would if you bought stabilized, milled flaxseed. Additionally, if you buy it in a container of ground flaxseed from the store, often it says to refrigerate to help protect it.”

Fish oil also contains high levels of Omega-3 and has the advantage of containing EPA and DHA. Fish oil, however, is not palatable to horses, and if fed, should contain additional flavors and be stabilized for storage.

Animal fats should not be fed to horses unless they have been processed and are in a powdered form. Animal fats are only 75 percent digestible by a horse.

Energy Balance
Before implementing a high-fat diet, it is important to assess the horse’s energy balance.

“We want to feed a high-fat diet to a horse because he needs the energy,” Lawrence says. “Match the level of fat that the horse needs to the amount of fat in the diet. Even though fat has other advantages, if we have a horse that is already too fat, then the last thing we want to do is give them a high-fat feed.

“Use condition scoring to assess the horse’s caloric intake. Evaluate the horse and determine that he needs the extra energy. If it is working hard and is too thin, then it needs a high fat diet.”

Horses that are ridden infrequently and are older, are often too heavy. These horses do not require the additional energy obtained from a high fat feed. Older horses with bad teeth can benefit from the high fat as it reduces their chewing requirement and reduces the amount of food they have to consume to reach their desired caloric intake.

High-strung horses often benefit from a high fat feed. These horses are usually hard keepers because they burn a lot of energy being hyper. Replacing calories that come from grain with calories from fat will also improve their behavior by decreasing the amount of nonstructural carbohydrates that they receive from corn, oats and barley that may contribute to hyperactivity.

Guidelines for Feeding Fat
Some horses will not eat well or may have digestive upsets on a high fat diet.

A horse’s total diet should not be comprised of more than 15 percent fat. Diets that exceed this upper limit will have a negative effect on fermentation in the hindgut. The excess, undigested fat will pass from the small intestine to the hindgut, where it will alter the microbial balance required for digesting cellulose in plant material. This may result in the horse going off its feed and getting diarrhea.

“The easiest way to supplement with fat is to buy a high-fat grain ration that has already been nutritionally balanced from a commercial feed company,” Lawrence says. “Switch over to that feed very slowly by trading a portion of the old, low-fat feed over a period of time. That period of time depends on the horse’s acceptability of fat. Trading a feed of less than five percent fat to one with eight percent fat can be done over a period of two or three weeks.

“Remember that the upper fat intake level of 15 percent is for the total diet. When an eight percent fat grain is fed with a three percent fat forage, the total dietary fat will only be approximately five percent fat. To illustrate, if we feed 8 pounds of an eight percent fat mixed-grain feed or pellet and 15 pounds of a three percent fat hay, the average of the total fat in the diet comes to a little less than five percent total fat.”

If you determine that the horse requires a higher percentage of fat because it’s too thin or you have increased its workload, you can go to a grain with a higher fat content or top dress the grain with supplementary fat.

Any vegetable oil can be used to top dress; however, due to the Omega-6 to Omega-3 ratio, soybean or canola oil is preferable to corn oil.

“Add a quarter of a cup per feeding and see how the horse accepts it,” Lawrence says. “You can add up to two cups per day. Add the fat slowly over a period of three weeks. Some horses that perform in extremely intense Olympic level sports add four cups of oil to a feed that’s already six percent, but that is highly unusual and typically two cups of oil per day will adequately increase the energy balance of the horse. If it doesn’t, there are some serious issues that need to be addressed by a veterinarian.”

Gaining Weight
Energy requirements between an easy keeper and a hard keeper can vary by 30 percent. To increase a horse’s body condition score (BCS) by one point will require a weight gain of approximately 45 pounds This can safely be achieved over a 60-day period.

Weight gain requires that the horse consumes more calories than it needs. Weight gain should be done slowly, especially if you are trying to achieve that gain through a high-grain diet. Increasing the horse’s total caloric intake by 15 percent should put the horse on target to meet the 45-pound goal. Increase the horse’s high fat grain ration from five pounds per day to seven pounds per day combined with good, quality hay.

Bridget Cook is a native of Australia and freelance writer. E-mail comments on this article to [email protected].


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