Risks Associated With Feeding Horses Traditional Bran Mashes

While steeped in tradition, feeding bran mashes can cause GI distress in horses. Learn why, and discover alternatives.

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Risks Associated With Feeding Horses Traditional Bran Mashes
Wheat bran has also fallen out of favor because of its high phosphorus level. | Photo: iStock

Q: I’ve always enjoyed giving my horse a warm bran mash in cold weather, but this doesn’t seem to be something people do much anymore. Is there still a place for wheat bran in my feed room?

A: Growing up I routinely fed a warm bran mash to my horse in the winter, especially on days when he worked hard. However it’s far more unusual now in part because we’ve realized that it might not be as beneficial as we once believed.

In my 1983 8th Edition of the British Horse Society and The Pony Club Manual of Horsemanship it states that a bran mash is a “very useful warm food after hard exercise and hunting.” It goes on to say that after adding boiling water to the bran, you should add a generous amount of salt along with some oats, and then feed once cool. It finishes by saying “bran mash has a laxative value, and it has everything to recommend it when fed once a week to horses in work and to invalid horses. It is also a convenient way to administer medicines such as worming compounds.”

So how did a feed and feeding practice that were once so popular fall out of favor? To better understand that you need to understand your horse’s digestive tract, as well as the composition of the feed.

About Diet Changes and Digestive Tract Upset

Most of us are well aware that changes to a horse’s diet should be made gradually over several days. The reason for this is that the digestive enzymes, the amount secreted as well as the bacteria in the horse’s hind gut, are somewhat specific to the diet being fed. Therefore, if you change the makeup of the diet the enzymes and digestive bacteria must adapt, and this takes time. In the meantime if too much new feed is fed the horse might not be able to fully digest it and can lead to digestive disturbance (e.g., diarrhea, gas, and colic, etc.).

As previously mentioned, horse people used to routinely feed bran mashes once a week, largely for their believed laxative effect. Since becoming more educated in equine nutrition, it’s fascinated me that—while we take great care not to suddenly change a horse’s diet when starting most new feeds—this logic goes out the window when it comes to a bran mash. Essentially, when you feed a bran mash once a week you’re breaking all the guidelines you typically follow in keeping your horse’s diet consistent. The “laxative effect” might be because the feed change is causing digestive distress! This is probably not the best method of ensuring your horse’s digestive contents stay on the move.

Wheat Bran’s Nutritional Imbalance

Wheat bran has also fallen out of favor because of its high phosphorus level. In fact wheat bran has an inverted calcium to phosphorus ratio, meaning that it contains more phosphorus than calcium. This is actually common in traditional grains such as wheat, oats, and barley. However, wheat bran is particularly high with a phosphorus content of about 1% and calcium at only 0.15%.

Researchers realized feeding diets with a lot of wheat bran increased the risk of developing secondary hyperparathyroidism, a condition that results from a calcium imbalance potentially caused by horses consuming a diet too high in phosphorus. “Big head” or “bran disease” was far more common when horse owners and managers fed traditional grains and wheat bran more commonly than we do today. In reality this condition is unlikely to result from feeding a bran mash once a week. It’s far more likely if bran or traditional grains are fed daily in a poorly balanced ration. Traditionally any number of unfortified grains could have caused a similar issue, but because, proportionally, brans add much more phosphorus per pound than the grains, they are often considered a larger problem. With the concern over big head and potential links to bran, much less wheat bran is now fed and most rice brans are fortified with additional calcium carbonate to neutralize the problem.

So, What’s Right About Bran?

Going back to the quote from my Manual of Horsemanship, if a bran mash has “everything to recommend it,” what’s it doing right, given the two already discussed areas of concern? First, the manual hints that bran mashes are generally welcomed by even the most picky eater. Often, after very long and heavy work such as fox hunting, horses might have a reduced appetite and the goal is to get the horse eating and the digestive tract moving. Some sick horses that have gone off feed can be tempted to eat with a bran mash. Therefore, a bran mash can be a very useful tool when faced with a horse that has gone off feed and will not eat anything else.

Second, adding salt to a bran mash is a great practice, especially when fed after work that might have incurred heavy sweat losses.

Alternative Warm Mashes for Your Horse

So, when you want to give a bran mash is there something else that might be more beneficial? Is there a better way?

If you already give your horse supplemental feed, whether it is pellets or a textured feed, add hot water to make a warm mash just as you would with wheat bran. This way you are creating the mash but using familiar feeds that are less likely to irritate the gastrointestinal tract.

If you only feed forage, purchase some hay pellets that are like the forage you feed and use them to make a mash.

Next add some salt, or if you already give salt every day and your horse has been sweating heavily, add an electrolyte. If you need to entice a picky eater or a horse that has gone off feed, try adding carrot or apple peelings. If you have your heart set on a weekly bran mash, then I suggest adding a small amount of bran to your horse’s every day feed so that the mash is not a novel feed to your horse’ digestive tract. But be careful to keep the amount of bran small and consider discussing with an equine nutritionist how to add bran to your ration while maintaining a balanced mineral profile.


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Written by:

Clair Thunes, PhD, is an equine nutritionist who owns Clarity Equine Nutrition, based in Gilbert, Arizona. She works as a consultant with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses and provides services to select companies. As a nutritionist she works with all equids, from WEG competitors to Miniature donkeys and everything in between. 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 U.K. Pony Club. Today, she serves as the district commissioner for the Salt River Pony Club.

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