My Horse is Gaining Weight on Free-Choice Forage! Why Isn't it Working?

By Juliet M. Getty, Ph.D.

Reasonable, gradual weight loss can be achieved by creating an environment that allows horses to eat and behave in sync with their normal instincts. Hormones such as insulin, cortisol, and leptin are in homeostasis, where the body achieves a state of equilibrium and performs as it should.

It starts with making the horse feel safe. The foundation of safety is knowing that there is always something to eat. Without this, the very underpinning of health becomes unhinged. Piling supplements and expensive feeds onto this insecure footing will make a trivial, insignificant, and short-term difference.

A steady, never-ending supply of appropriate hay/pasture will allow your horse to realize that he can eat effortlessly. In very little time, he will begin to self-regulate his forage intake and eat only what his body needs to maintain condition.

There are cases, however, where the horse not only doesn’t self-regulate, he actually gets heavier. Why is this? And if this is your horse, is there no hope? Do you simply have to go back to restricting hay? There are several reasons why this can occur and no, you do not and should not go back to restricting hay.

Free-choice forage is fundamental but it is not enough

If you are expecting to simply give your horse all the hay he wants and he’ll start to miraculously lose weight, while his nutrient intake remains inadequate and there are significant stressors in his life, you will likely be disappointed. Free-choice forage feeding will, however, improve his behavior and digestive health, even without weight loss. But to have an impact on his weight, other practices need to be in place.

Four components should be considered

An excellent diet, stress reduction, the right environment, and patience are key ingredients to making weight loss a reality. Below are factors that can make this happen. I realize that for many of you, it is not feasible to implement all of them. My goal is to give you the ideal situation; your goal needs to be to come as close to the ideal as possible. Even making some of these changes will improve your horse’s health.

1. Excellent Diet

Appropriate forage

The hay and/or pasture need to be low in sugar and starch, as well as low in calories, because your horse will be eating a lot of it. Testing your hay is critically important. If Ethanol Soluble Carbohydrates (ESC) + Starch exceeds 11% on a dry matter basis, you’ll want to seriously consider soaking it.[i] If the hay supply changes frequently where your horse is boarded, consider buying your own hay; even a one month’s supply is worth testing.

Pasture grazing, of course, is ideal, but it can be tricky because its sugar and starch content varies so much. It, too, is worth testing periodically at the best and worst times of the day.[ii] The ideal is a pasture with a mix of healthful forage. Many horses can lose weight while pasture grazing in such conditions; it is the most natural, least stressful state for the horse, and provides the most nutritious whole food.

Aggressively attack inflammation

Where there’s body fat, there’s inflammation, leading to insulin and leptin resistance. A vicious cycle ensues because leptin resistance prevents the brain from telling the horse that he’s had enough to eat, and insulin resistance tells the horse to hold on to body fat. In both of these situations, body fat increases, further exacerbating inflammation.

To effectively reduce inflammation, boost the diet with antioxidants, anti-inflammatory herbs, key minerals, and the right balance of omega 3s to 6s, preferably from supplements that provide wholesome ingredients without the use of added preservatives. Please review articles[iii] in my website’s resources for specific ways to accomplish this.

Get rid of the concentrates

Supplements can be added to a small amount of a carrier feed such as hay pellets, non-GMO beet pulp, or whole foods (avoid soy). But do not feed large amounts of any “grain” including those that contain cereal grains (oats, corn, barley, rice, etc.), molasses, or added vegetable oils; these do nothing except add unnecessary calories.

2. Stress Reduction

Forage restriction is incredibly stressful

The horse’s digestive tract is designed for a continual flow of forage; without it, the horse will be in physical pain, mental discomfort, and prone toward a hormonal response that destroys health and promotes obesity.[iv] If he runs out of forage, even for a few minutes, your horse’s system will register this as an impending famine and his body will hoard fat.

The damage from prolonged forage restriction can be difficult to repair

The only way to fix your horse is to help him return to his natural state. However, the longer a horse lives as an overweight, stressed animal, the more inflammation he will have within his system, making it difficult it to bring that horse back to a normal weight, free of leptin or insulin resistance. Years of enduring forage restriction will definitely take its toll. But the solution is not to continue down this destructive path; the solution is to try to make things better.[v]

Grazing muzzles may defeat your purpose

If your horse tolerates a grazing muzzle, it can allow him to spend some time out on pasture with his buddies. But a muzzle can defeat your purpose if it causes frustration and its attendant cascade of stress-induced hormonal reactions. So pay attention to your horse. Even if he accepts the muzzle, limit its use to no more than 3 hours per day. Muzzles are hardly ideal—they do not really allow sufficient forage consumption for healthy digestive functioning, but the benefits of exercise and companionship in the pasture can outweigh the downside of short term reduction in forage intake. Make certain that your horse can drink water and that water drains well.

3. The Right Environment

Movement is so important

Movement does more than burn calories; it keeps your horse whole, physically and psychologically. Confinement to a small paddock (even though it is outdoors), or worse, to a stall, for hours on end, reduces circulation, increases the horse’s sense of vulnerability, increases susceptibility to depression, creates inflammation throughout the body, decreases the metabolic rate, reduces immune function, and depresses digestive tract motility, to name only a few outcomes. All of these have the same impact on your horse’s weight – they can lead to obesity because of the hormonal and metabolic responses that tell the horse to hold on to body fat.

Freedom to roam and interact with other horses

Horses require the protection of a herd. They are also social animals and need the interaction of close physical contact; merely seeing other horses over the fence is not enough.

Room to roam, along with freedom to choose whether to be out in the sunlight, or under a tree, or in a shed -- perceiving he has options for comfort and safety is a calming force for the horse.

Slow feeders can be wonderful when used correctly

Slow feeders come in a variety of styles and methods.[vi] Allow your horse to gradually become accustomed to eating from them by also providing loose hay. Feeders need to be kept full at all times, the hole size for netted styles should not be smaller than 1.5 inches, and, depending on design, they should be kept low or on the ground to simulate the horse’s natural eating stance. Provide many of them throughout his area to encourage grazing.

4. Patience!

At first, he will overeat

Give a horse all he can eat, and at first he will overeat, a lot! It can be difficult to watch. Be sure you’ve tested your hay and it is suitable. Then give him more than he could possibly eat so that there is some left over. If you don’t give him enough and he eats it all, you will not accomplish your goal. But if he has so much that he can’t finish it, and he can leave and return to find it still there, he will eventually reach the magic moment – he will walk away! Eventually, he will eat far less than he did at the beginning.

Many barn managers are not willing to do this because it seems like a waste of money. But in actuality, the horse will eat less once he self-regulates than he did when he was only getting a set ration of hay.

Give it enough time. Most horses start to self-regulate within a couple of weeks. Some take a couple of months. And those who are leptin resistant take even longer.

Sometimes it’s gas, not fat

Forage contains large amounts of fiber, which is fermented in the horse’s hind gut (cecum and large colon), resulting in gas formation. This is normal and healthy, but it can make your horse look pregnant. This is not fat; it’s gas--otherwise known as a “hay belly.” Do not let it concern you. Your horse will adjust. If it gets excessive, however, it would be best to help out the microbial flora in the hind gut by administering a good prebiotic.[vii]

Horses will gain weight at first

Overeating naturally leads to weight gain. But it is only temporary. Allow for movement, feed an anti-inflammatory diet, get rid of stress, and you will have a different horse.

Abandon the conventional weight loss mantra!

“Eat less!” This continues to be spouted by many horse owners and equine professionals. In fact, equine research in this area has revolved around reducing forage, often with “positive” results. But it is exceedingly short-sighted! What they don’t tell you is how those same horses are doing a year later. Nor do they examine the inflammatory, metabolic, endocrine, physiologic, and even hypothalamic damage in the brain that results from forage restriction.[viii]

We know about the damage this causes to humans. Why do we use this method with horses? Excessively reducing calories will result in weight loss. But wait! Give it some time and the weight not only creeps back but even more weight is put on. Recently, the New York Times did a piece on the “Greatest Losers,”[ix] a reality TV show where overweight men and women underwent extreme dieting and exercise and were praised by all in their efforts as they showed off their newly trim selves. Six years later, they were back to where they started, or worse, due to a shift in normal metabolism.

It is no different for horses. Prolonged forage restriction ultimately resets the metabolic rate to a slower level. In addition, the body’s hormonal response changes, making it very difficult for the horse to successfully keep off the weight without sacrificing health and quality of life.

Bottom line

Why not simply allow your horse to be healthy? Weight loss the wrong way will ensure that your horse will get fat again. Being patient, reducing inflammation and stress, and creating a healthy environment will do the trick. Sure, take away calories from concentrated feeds – that’s fine. But never, never restrict forage.

This article originally appeared on Getty Equine Nutrition and is published here with permission.

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