Commentary

Possible Problems Caused by Feeding Horses Bran Mashes

Possible Problems Caused by Feeding Horses Bran Mashes

Increasing hay intake in winter will do a much better job of helping your horse stay warm than feeding a warm mash.

Photo: Anne M. Eberhardt/The Horse

Q. I’ve been worrying about my horse in this bitterly cold weather. He only gets hay to eat, and I’d like to do something for him that will help keep him warm. I’ve been thinking about giving him a warm mash, because I hear many people swear by bran mashes in the winter for this purpose. Is this a good idea, and will it work?


A. On a cold day, there’s something very appealing to most of us about a bowl of hot soup or stew, and therefore it’s tempting to want to do something similar for our horses. You’re correct that, traditionally, people often fed horses warm bran mashes in cold weather. But, in reality, this does little to warm your horse.

Bran mashes also had other purposes. In cold weather horses tend to consume less water, increasing the risk of dehydration and impaction colic. A wet bran mash acts as a good way of getting more water in to your horse because mashes tend to be very palatable.

As a result, feeding infrequent bran mashes is no longer recommended for horses.

Dr. Clair Thunes

People also believed a weekly bran mash would keep the bowels moving; however, we now understand that this is achieved in a less than desirable way. The passage of loose manure results from disrupting the delicate balance of bacteria in the horse’s cecum and large colon. As a result, feeding infrequent bran mashes is no longer recommended for horses. Additionally, feeding bran frequently can cause problems with the calcium-phosphorus balance in some horses’ rations.

A better approach to help keep your horse warm in winter is to feed plenty of forage. Those same bacteria in your horse’s cecum and large intestine that become disrupted by sudden diet changes are responsible for breaking down complex carbohydrates. Forages provide large amounts of complex carbohydrates.

Microbial breakdown of complex carbohydrate is a process of fermentation. Fermentation in the cecum and large colon occurs in the absence of oxygen, and this anaerobic degradation of organic compounds results in the release of volatile fatty acids (VFAs). These VFAs are absorbed by the horse and converted to useable forms of energy.

Without the bacteria, yeasts, and other organisms involved in this fermentation process, horses wouldn’t be able to utilize the complex carbohydrates within forages. This is because, like other mammals, horses don’t themselves create the enzyme necessary to break apart the bonds holding complex carbohydrates together.

While it’s possible for a horse at maintenance who’s consuming an all-forage diet to meet approximately 80% of his daily calorie requirement from the fermentation of complex carbohydrates (the remaining calorie requirements comes from simple carbohydrates and fats in the forage), it’s not a 100% efficient process. Some of the energy released when complex carbohydrates are broken apart is lost as heat and helps to maintain body temperature. Essentially, the heat produced via fermentation of forage in the horse’s hindgut is like having an internal furnace.

Feeding plenty of forage during cold weather will help your horse maintain core body temperature. Increasing hay intake in winter will do a much better job of helping your horse stay warm than feeding a warm mash. However, feeding dry hay does not address the main benefit of the wet mash, which is increased water intake. One way to achieve both internal heat production from forage fermentation and increased water intake is to feed soaked hay pellets or beet pulp.

Both hay pellets and beet pulp provide sources of complex carbohydrate that require fermentation. If your horse is only fed hay, feeding soaked hay pellets might be the better choice if these soaked meals are not fed every day. Because the pellets are closer in nutritional composition to the hay you’re already feeding than beet pulp, there should be less risk of digestive disruption if the hay pellets are fed infrequently. Keep in mind, though, that your hay and the hay pellets will have nutritional differences, so a risk still exists. However, you would be reducing that risk as much as possible. If your horse actually needs extra calories (beet pulp provides more calories per pound than hay), and you will feed these meals daily, then beet pulp might be the better solution.

Soaked hay pellets fed with a little salt will provide complex carbohydrates for fermentation, water for hydration, and the salt will help to stimulate thirst in the future. Maximizing forage intake is the best way to help your horse stay warm from the inside out this winter, and adding water to meals will help ensure he stays hydrated. Certainly, if it makes you feel better, using hot water to make your soaked meal isn’t detrimental. Just make sure that it is not scalding when you feed it.

About the Author

Clair Thunes, PhD

Clair Thunes, PhD, is an independent equine nutrition consultant who owns Summit Equine Nutrition, based in Sacramento, California. She works with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the United Kingdom Pony Club. Today, she serves as the regional supervisor for the Sierra Pacific region of the United States Pony Clubs. As a nutritionist she works with all horses, from WEG competitors to Miniature Donkeys and everything in between.

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