Super Fibers for Horses: Beet Pulp and Soy Hulls

Designed to handle a near continual supply of forage, the gastrointestinal tract of the horse, especially the hindgut, grinds away slowly, turning fiber into usable energy. Some fiber contains more energy than others. Rapidly fermentable fiber sources, sometimes called super fibers such as beet pulp and soy hulls, offer many benefits to horses, including an upsurge in energy from normal pasture grasses and hay.

From time to time, the nutritionists at Kentucky Equine Research(KER) are asked which super fiber is best, beet pulp or soy hulls, and why the two feedstuffs aren’t similarly priced if they provide the same nutrients to the horse.

“One super fiber has no great advantage over another. Usually, choosing one is just a matter of which is more available in the area and which fits better into the horse’s feeding program,” said Catherine Whitehouse, M.S., a nutrition advisor with KER.

Beet pulp sometimes gets a bad rap because of its involvement in choke. “Certainly, there have been instances of beet pulp shreds causing choke, but obstruction of the esophagus has more to do with how a horse eats rather than what a horse eats. A horse that bolts its feed will always have a greater chance of a blockage than a horse that chews and swallows slowly and methodically,” said Whitehouse. “And once a horse has choked, it seems predisposed to the problem.”

Feed stores and manufacturers often have beet pulp on hand, available in 50-lb (23-kg) bags in either shred or pelleted forms. “As with any new feedstuff beet pulp is gradually added to a concentrate meal until the full measure can be fed. This is particularly important with a super fiber that has the potential to produce excessive gas, like beet pulp, if the microbial population doesn’t have time to adapt to it,” said Kathleen Crandell, Ph.D., longtime nutritionist for KER.

If there is concern about the sugar in molassed beet pulp, it can be rinsed a few times before being soaked to remove excessive sugar. Alternatively, unmolassed or plain beet pulp is sometimes available.

The amount of beet pulp added to a meal varies based on the energy and fiber needs of the horse. “For example, if beet pulp is being fed because a mid- to poor-quality hay is the only forage available, then larger amounts of beet pulp would be given to increase the energy density of the diet. On the other hand, if a diet is adequate in forage but beet pulp is being fed to replace some of the starch calories to reduce the amount of grain the horse requires, then typically smaller amounts would be used,” explained Crandell.

Researchers have fed up to 3 g/kg body weight (dry weight) per day, which would equate to 3.3 lb for a 1,100-lb (1.5 kg for a 500-kg) horse, without any issues, but it is not wise to replace all of the forage in the diet with beet pulp because of its rapid fermentation and high fiber digestibility.

Soy hulls might be more difficult to find bagged and ready for sale. If you have a feed manufacturer nearby, you may be able to purchase them, as they are often used in textured and pelleted feeds. An informal survey of local feed mills in central Kentucky revealed that about half had soy hulls available for sale in 50- or 100-lb (23- to 46-kg) quantities, while the other half only sold them by the ton.

Feeding soy hulls to horses is not as straightforward as beet pulp because of the lower palatability and the form in which they are typically available. Mostly, they can be purchased pelleted, but plain soy hull pellets are not tasty to horses, and the hardness of the pellets can deter them from wanting to eat much. They are definitely better softened with water and mixed with some type of palatable feed, although a hungry horse can often adapt to unusual offerings if given time. This is the reason why soy hulls are usually mixed into commercial pelleted feeds and not typically fed alone.

“Regarding the price differences, typically soy hulls are less expensive than beet pulp. In combination with other factors, such as growing expenses and demand, pricing often depends on the distance the product must travel from where it is grown or processed,” explained Crandell.

Do you think your horse might benefit from the addition of an energy-dense super fiber? Start a nutrition evaluation for your horse now!