Many horse owners opt to give bran mashes to their horses on Sunday evenings, after a big competition, or on a cold winter night. Bran mash is made by mixing wheat bran with ample warm water to produce a slurry, then adding in other grains, apples, carrots and/or other treats.
The premise is to give the horse a bit of a treat or warm him up. While there is nothing wrong with wanting to give your horse a tasty treat, there may be better options than a traditional “bran mash.”
Bran mashes are believed to have laxative properties, which means they draw water into the feces, to facilitate bowel movements. For horse people, we tend to think we help “move things along” with bran mashes. This could be desirable in cases where an owner is worried that their horse hasn’t been drinking enough water, or may be a little dehydrated from competition, wherein the material in the digestive tract may be dried out and not move along as well, leaving the horse at risk for blockage. In fact, however, research has shown that even watery bran mashes don’t significantly affect the water content of feces. To that end, wheat bran has very little dietary fibre; only 10% crude fibre, compared to 17% in beet pulp or 16% in oat hulls.
Regarding its other nutrients, wheat bran does have a fair amount of protein (17%) and some B vitamins. However, it is very low in calcium (0.14%), and very high in phosphorus (1.1%). These mineral values have the potential to cause an inverted Ca:P ratio, which should be about 2:1 (2 parts calcium, 1 part phosphorus). Wheat bran is about 1:10. It is not recommended to incorporate wheat bran into any regular equine diet without a concerted effort to balance those minerals. It is unknown what a weekly mineral imbalance might do, though long-term imbalance of Ca and P can result in nutritional secondary hyperparathyroidism, or “big head disease,” in which calcium is removed from bone to correct the low blood concentration and replaced with an unmineralized matrix.
Another concern regarding feeding weekly or sporadic bran mashes is that it has the potential to disrupt the horse’s normal microbial environment. We know that the equine digestive tract houses millions of microbial organisms that function to help ferment fibre in the equine diet to provide energy and vitamins (B complex and vitamin K) for the horse. These microbes live in an ecosystem that can be disrupted upon the sudden exposure to different substrates due to a new dietary component, which could trigger colic or laminitis. We typically think of horses getting an excess of starch from breaking into a grain bin, or overconsumption of rich pasture grass, but wheat bran is actually 30% non-structural carbohydrate (!) and could itself be problematic. In fact, the looser stools you may have attributed to the laxative/fibre affect from the bran may actually have been caused by some mild digestive upset.
Another common thought to giving a warm bran mash is to warm up the horse on a cold winter’s night. This might provide a momentary bit of warm comfort (like a cup of hot tea), but won’t actually warm the horse. In fact, simply providing ample forage provides a healthier substrate for those microbes to ferment, which gives off additional heat as an “internal combustion.”
Most horses will consume about 1.5% of their body weight in dry forage such as hay, per day, but have the capacity to consume more, up to even 3% of their body weight. Offering ample hay (one or two extra flakes, or even “free choice”) provides additional calories for generating body heat, plus the heat of fermentation gives longer lasting warmth.
In an effort to encourage more water into your horse, it is possible to simply add water to his regular grain mix. Most horses won’t be put off by the different texture. Water consumption can also be enhanced by keeping the water warmer (between 7-18°C) offering electrolytes to encourage drinking, or even flavouring some of the water with apple juice while away at a competition, to mask any new tastes in “away” water.
There are plenty of other ways to give your horse a treat that might be better than your traditional bran mash. I like feeding the same thing day in and day out (horses are built for just that), but adding in some carrots or apples is always a nice treat. If you think your horse might benefit from a little bit of a cleanse, adding some soaked beet pulp into his regular diet might be helpful.
Remember that horses are creatures of habit, as they evolved to eat forages day in and day out. When we feed concentrates, we know to provide many small meals per day, and on a regular schedule. Introducing novel feeds, even as a well intended reward, may not be the best idea for their gastric health. An apple and some extra pats might just be enough.