Soybean Hulls, Super Fibers, and Horse Feeds

Forage-based diets are the best way to maintain a healthy digestive tract in the horse. The fiber in forages is a major source of energy for horses, and they can thrive on forage alone. Some horses, such as those in heavy work, require additional energy in the form of concentrates.

“In keeping with the spirit of offering a horse as many calories as possible in the form of fiber, there are highly digestible alternatives to conventional hay that have proven very useful for incorporation into commercial feeds. Examples include beet pulp and soybean hulls,” noted Kathleen Crandell, Ph.D., Kentucky Equine Research nutritionist.

Soybean hulls are the outer layer of the soybean separated during the processing of the beans and have about 30% more digestible fiber than common hay. This makes them an excellent energy source for the horse.

“Substituting soybean hulls or other ‘super fibers’ in a horse’s diet can increase the amount of fiber fed while still providing adequate energy,” advised Crandell, a coauthor on a recent study focusing on the impact of soybean hulls on equine digestion*.

Due to the promising results of soybean hulls on equine digestion obtained during previously published studies, Crandell and colleagues further analyzed the effect of soybean hulls in equine diets.

Mares were fed diets composed of 60% forage (coastcross hay) and 40% concentrate. The concentrate contained increasing levels of soybean hulls (range, 0-28%). Various measures of intestinal health and digestion were obtained, including apparent digestion, pH of feces (an indicator of starch fermentation in the hindgut), and microbe populations in the large intestine.

“The inclusion of up to 28% soybean hulls in a concentrate does not appear to negatively affect digestibility, the microbial population in the hindgut, or pH,” reported Crandell.

She added, “Soybean hulls are a safe ingredient for equine concentrates and help increase the amount of fiber in the diets of horses.”

*Kabe, A.M.G., A.D. de Souza, R.L. de Moro Sousa, et al. Soybean hulls in equine feed concentrates: Apparent nutrient digestibility, physico-chemical and microbial characteristics of equine feces. Journal of Equine Veterinary Science. In Press.