Soybean hulls are a byproduct of soybean processing for soybean oil and soybean meal.
During processing, soybeans are rolled or cracked to break the whole bean into smaller pieces and the hulls are separated by an air stream.
Hulls are usually toasted to destroy their urease activity and ground to the desirable particle size.
The soybean hull is high in fiber (73%) and low in protein (9.4%). The protein is highly degradable, while the cell wall is low in lignin and highly digestible.
Soy hulls are very palatable and are typically used to increase bulk in rations of fine texture. Soy hulls are not typically used in aquaculture feeds, but they are a good source of digestible fiber and have been found to be an effective fiber source for use in grass carp feeds.