Soybean hulls are a by-product of the extraction of oil from soybean seeds (Glycine max (L.) Merr.). After entering the oil mill, soybeans are screened to remove broken and damaged beans, and foreign material (Extension, 2008). The beans are then cracked, and their hulls, which mainly consist of the outer coats, are removed (see figure above). Hulls are fibrous materials with no place in human food, but are very valuable for ruminants (Ipharraguerre et al., 2003). Soybean hulls are often reintroduced in the final oil meal in order to reduce its protein content, resulting in soybean meal types with a maximum protein + fat guarantee of 44 to 48%. However, this end use decreases when the demand for high protein soybean meal increases. Soybean hulls are thus available and very valuable feeds for on-farm feeding of cattle (Extension, 2008).
Soybean hulls are light, flaky, and bulky. They require special consideration when handling: closed feeders are necessary when soybean hulls are fed outside, since the wind tends to blow the hulls away. During transportation, closed and covered trailers are also required (Extension, 2008). Pelleting hulls is a way to reduce bulkiness and reduce transportation costs, even though many manufacturers prefer unpelleted hulls to prepare compound feed (Blasi et al., 2000).