Pentosans
Wheat bran contains pentosans, which are thought to have antinutritional activities in poultry and result in depressed nutrient utilization and poor growth (Choct et al., 1992).
Phytase activity
Wheat bran has a high phytase activity, which is beneficial to phosphorus availability in pig and poultry diets. However, this phytase activity may be considerably reduced when wheat bran is processed into pellets because heat treatments destroy phytase (Cavalcanti et al., 2004).
Lipase hydrolytic rancidity
Wheat bran contains a very heat-stable lipase that causes hydrolytic rancidity and is more active if the bran is finely ground (Allen et al., 1994). However, wheat bran contains low amounts of fat and no health problems due to rancidity have been reported in livestock.
Nutritional Secondary Hyperparathyroidism
Large amounts of bran can induce calcium deficiency in horses, known as Nutritional Secondary Hyperparathyroidism, and also as "big head disease", "bran disease" or "Millers Disease", because milling companies often fed their horses rations containing large amounts of bran (Kohnke et al., 1999). Growing bone is frequently rachitic, and brittle and fractures may be common and heal poorly. Swelling and softening of the facial bones and alternating limb lameness are frequently reported (Kahn, 2005).