Soybean meal is used in food and animal feeds, principally as a protein supplement, but also as a source of metabolizable energy. Some, but not all, soybean meal is produced from the residue left after oil extraction. (Removal of the oil, which is used mostly in food, but also for industrial oils, soaps and biodiesel, involves crushing and either pressing or solvent extraction.) Some, but not all, soybean meal contains ground soybean hulls. Soybean meal is heat-treated during production, to denature the trypsin inhibitors of soybeans, which would otherwise interfere with protein digestion.)
Major kinds of soybean meal
Three main kinds of soybean meal are produced:
- • full-fat soybean meal, made from whole soybeans. It has a high metabolizable energy concentration. (For example, metabolizable energy for swine in this product is about 3.69 megacalories (i.e. 15.4 MJ) per kg dry matter.) Crude protein concentration is about 38 percent (as fed). This kind of product is sometimes fed to various classes of livestock.
- • defatted soybean meal, containing no hulls. This product has an intermediate energy concentration. (For example, metabolizable energy for swine in this product is about 3.38 megacalories (i.e. 14.1 MJ) per kg dry matter.) Crude protein concentration is about 48 percent.  This percentage [which is commonly used in describing the product] is calculated at the typical as-fed moisture content of 88 percent. Thus, crude protein concentration expressed on a dry matter basis is 54 percent. This product is commonly fed to swine, broilers and layers. 
- • defatted soybean meal, containing soybean hulls. The hulls are readily digestible by ruminant livestock. This product is often fed as a protein supplement for domestic ruminants. Ruminant-metabolizable energy concentration is about 3.0 megacalories (i.e. about 12.5 MJ) per kg dry matter, and crude protein concentration is about 44 percent.  The latter percentage [which is commonly used in describing the product] is calculated at the typical as-fed moisture content of 90 percent Thus, crude protein concentration on a dry matter basis is 49 percent.
Use in animal feed
Globally, about 98 percent of soybean meal is used as animal feed. Of the US soybean production magnitude from 2010 through 2012, about 44 percent was exported as soybeans, and 53 percent was crushed in the US. Of the crushed tonnage, 19 percent was recovered as soybean oil and the remainder was recovered as soybean meal. Of the total US soybean tonnage produced, about 35 percent was fed to US livestock and poultry as soybean meal. Most of the remaining soybean meal produced in the US was exported. It has been estimated that, of soy meal fed to animals in the US, 48 percent is fed to poultry, 26 percent to swine, 12 percent to beef cattle, 9 percent to dairy cattle, 3 percent is used in fish feed and about 2 percent in pet food. Although this implies that the tonnage of soybean meal fed to other species is relatively minor, such use is not unimportant. For example, for rapidly growing lambs on low-protein feeds, soybean meal can be an important supplement to ensure adequate protein intake, and partly because of its palatability, soybean meal is often recommended for use in starter rations when creep feeding lambs.
Uses as human food
Globally, about 2 percent of soybean meal is used for soy flour and other products for human consumption. Soy flour “provides the basis for some soy milks and vegetable protein”, and is marketed as full-fat, low-fat, defatted and lecithinated types.
Most studies of phytoestrogens in soy have identified the isoflavones genistein and daidzein as its principal phytoestrogenic substances. For several soy flour samples analyzed by various persons using high-performance liquid chromatography, daidzein content ranged from 226 to 2100 micrograms per gram, and genistein content ranged from 478 to 1123 micrograms per gram. For four analyses of defatted soy meal, the concentrations were 616 and 753 micrograms per gram, respectively; for one analysis of soybean meal (whole), concentrations were 706 and 1000 micrograms per gram, respectively. Although reproductive physiology of sheep is particularly sensitive to phytoestrogens, soybean meal supplementation of ewe lambs or ewes on pasture in some studies has been found to have no detrimental effect on reproductive performance.
- Stein, H. H., L. L. Berger, J. K. Drackley, G. C. Fahey Jr, D. C. Hernot and C. M. Parsons. 2008. Nutritional properties and feeding values of soybeans and their coproducts. Soybeans chemistry, production, processing, and utilization. AOCS Press, Urbana, IL. pp. 613-660.
- Soybean Feed Industry Guide. 2010. 1st Ed. https://cigi.ca/wp-content/uploads/2011/12/2010-Soybean-Feed-Industry-Guide.pdf
- Composition. Soy Meal Info Center. http://www.soymeal.org/composition.html
- National Research Council. 2000. Nutrient requirements of beef cattle. National Academies Press, Washington. 232 pp.
- Anderson, S. J., J. K. Merrill, M. L. McDonnell, and T. J. Klopfenstein. 1988. Digestibility and utilization of mechanically processed soybean hulls by lambs and steers. J.. Animal Sci. 66: 2965-2976.
- National Research Council. 2007. Nutrient requirements of small ruminants. National Academies Press, Washington. 362 pp.
- Soy facts. http://www.soyatech.com/soy_facts.htm
- United States Department of Agriculture, National Agricultural Statistics Service. Agricultural Statistics 2013.
- Cromwell, G. L. 2012. Soybean meal: An exceptional protein source. Soybean Meal InfoCenter; Ankeny, IA. http://www.soymeal.org/ReviewPapers/SBMExceptionalProteinSource.pdf
- Wahlberg, M. Alternative feeds for sheep. http://www.apsc.vt.edu/extension/sheep/programs/shepherds-symposium/2002/12_alternative_feeds.pdf
- Essential nutrient requirements of sheep. New Mexico State University. http://aces.nmsu.edu/sheep/sheep_nutrition/essential_nutrition.html
- Greiner, S. 1999. Sheep update: creep feeding lambs. Virginia Tech, Virginia State University, Virginia Cooperative Extension. http://www.sites.ext.vt.edu/newsletter-archive/livestock/aps-99_03/aps-0037.html
- Soy fact sheets. Soy Foods Association of North America http://www.soyfoods.org/soy-products/soy-fact-sheets/soy-flour-fact-sheet
- Soy flour. U. S. Soybean Export Council. http://ussec.org/why-u-s-soy/about-soy-2/soy-protein/soy-flour/
- Reinli, K. and G. Block. 1996. Phytoestrogen content of foods—a compendium of literature values. Nutrition and Cancer 26: 123-148.
- Adams, N. R. 1995. Detection of the effects of phytoestrogens on sheep and cattle. J. Animal Sci. 73: 1509-1515.
- Yoder, R. A., R. E. Hudgens, T. W. Perry, K. D. Johnson and M. A. Diekman. 1990. Growth and reproductive performance of ewe lambs fed corn or soybean meal while grazing pasture. J. Animal Sci. 68: 21-27.
- Molle, G., S. Landau, A. Branca, M. Sitzia, N. Fois, S. Ligios, and S. Casu. 1997. Flushing with soybean meal can improve reproductive performances in lactating Sarda ewes on a mature pasture. Small Ruminant Research 24: 157-165.
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