Bruce, K.J., L.K. Karr-Lilienthal, K.E. Zinn, L.L. Pope, D.C. Mahan, N.D. Fastinger, M. Watts, P.L. Utterback, C.M. Parsons, E.O. Castaneda, M. Ellis, and G.C. Fahey, Jr. 2006. Evaluation of the inclusion of soybean oil and soybean processing by-products to soybean meal on nutrient composition and digestibility in swine and poultry. J Anim Sci. 84:1403-1414. Link to full text (.pdf)

Take-home message:

• Addition of either gums or soapstock, or a combination of gums, soapstock and weeds/trash, leads to a decrease in amino acid digestibilities.
• There was no effect of addition of weeds/trash.
• Roasted soybeans were less digestible than soybean meal.