Bran is a byproduct of flour production and is one of the richest grain feeds. It should be free flowing and free of dust. Please make sure that the label says 100% wheat bran and contains no middlings which could cause colic. Bran is an essential part of mash, which should be fed once or twice per week; otherwise I do not recommend the feeding of bran on daily basis and definitely not in larger amounts. When fed as a part of mash it is helpful during various digestive disturbances, illnesses of some respiratory organs and in colic prevention, especially in a case of depleted (half empty) digestive track after strenuous work, because its weight in relevance to its volume. Prolonged daily feeding of bran can cause weakening of digestive organs. When fed frequently and dry in larger amounts it has the tendency to irritate the lining of the intestines. If fed daily over a long period of time, bran may actually contribute to the formation of enteroliths.
As you can see there are many negative facts about bran that are often over-amplified by some authors that often scare people from feeding bran to horses. The bran is an essential part of good feeding program when used with flax seed as part of mash once or twice per week.
Nutritional values: 15% crude protein, 10 MJ DE/kg, 11% fiber, 3% oil, mild laxative, improved skin and coat condition, good source of protein, some anti-bacterial values (poultice), low in calcium.