How Good is Bran Mash for Horses? - Feeding Pros and Cons


Can I overdo bran mashes? I’ve been giving more with the long spell of subfreezing weather. SH, Tennessee

Dear SH,

Unfortunately yes. As much as we love to prepare a warm, tasty bran mash with our horse’s favorite ingredients, this traditional treat may be doing more harm than good. Turns out bran mashes upset the nutritional balance of the diet and may not even prevent or treat the problems we’re giving it for in the first place.

One of the problems with bran mashes is the imbalance in the calcium to phosphorus ratio. Horses should get somewhere between 1 part calcium to 1 part phosphorus (1:1) or 2 parts calcium to 1 part phosphorus (2:1). Bran has a ratio of 1:12, which means it has a lot more phosphorus than calcium. Creating an upside-down balance between these two important minerals can lead to a condition called “Big Head Disease,” where the horse pulls calcium out of its bones in order to rebalance the ratio.

Another problem with a weekly bran mash or an occasional bran mash before or after a trip is that it is a sudden change in the horse’s diet, something we’re taught never to do. The beneficial bacteria that live in the horse’s GI system need time to adapt to any new feeds. Bran is made up of complex carbohydrates that require bacteria to ferment them so it especially needs this “break in” period. Some of these complex carbohydrates are completely indigestible in the horse, so bran does tend to “bulk up” manure. However, research has shown that even when as much as 50% of the diet consists of bran there is still no laxative effect. Any stool softening or additional water you see in the feces after feeding bran is more likely diarrhea from a sudden change in the diet.

So if you’re feeding a bran mash to heat your horse up from the inside on cold winter days, try feeding more hay. If you’re feeding a bran mash to get more water into your horse, try adding electrolytes to the diet (and using heated buckets—studies prove horses drink more water when it is warmed). If you’re feeding a bran mash to bond with your horse, there are lots of other things you can do to remind him you’re his friend such as extra grooming, carrot stretches or clicker training.