Warm bran mashes have a very long history of use in equine feeding, especially in winter, but lately have come under attack. Is this the yummy comfort food it has been claimed to be, or actually potentially harmful? As is usually the case, the truth is in between these extremes.
There is no denying the palatability factor. Any horse with a healthy appetite will dig into a bran mash. The simple mash recipe of bran, water and salt is a warming and hydrating meal. So what’s the problem?
“Bran Disease”, aka Big Head, Miller’s Disease, nutritional secondary hyperparathyroidism is a metabolic disorder of bone caused by a long term intake of a diet higher in phosphorus than calcium. Bran is very high in phosphorus and contains phytate which can make the situation worse by binding calcium to some extent and preventing absorption.
If you only feed a bran mash occasionally, this really isn’t an issue. If you want to feed it regularly, the solution is easy. Feed one pound of alfalfa for each pound of bran (be sure to actually weigh it) to correct the imbalance. A hearty bran and alfalfa mash is an excellent way to help meet the very high protein, calcium and phosphorus requirements of pregnant or lactating mares and growing horses.
You may have heard or read that the phytate in bran will also bind phosphorus and zinc, making them unavailable. This is true in humans but not in horses. Horses can ferment the phytate, releasing all minerals. Only calcium is affected because the fermentation takes place in the hind gut, where calcium is not well absorbed but other minerals are.
Finally, detractors say that the laxative effect sometimes seen with bran is actually harmful because it means the organisms in the hind gut have been disturbed. However, the same thing can happen with grain, change in hay or too rapid an introduction to pasture. It’s not a reason to avoid bran. Like anything else, bran should be introduced slowly in gradually increasing amounts.
When care is taken to keep minerals in balance, bran is an excellent feed for horses. It has a caloric content equivalent to oats but with only half as much starch. Protein is high at 17% and it is an excellent natural source of phosphorus which is low in the majority of hay types. The high palatability makes bran mash a great addition for picky eaters and the texture is ideal for older horses with chewing issues.
Eleanor Kellon, VMD