A finishing study was conducted to evaluate feeding whole (WSB) or roasted (RSB) soybeans at 12 or 16% of diet DM compared to feeding 9% soybean meal (SBM), 16% wet distillers grains (WDGS), or a corn control with urea (CON). Crossbred yearling steers (n = 504; initial BW = 422 kg) were utilized in a generalized randomized block design with 8 pens per treatment and 9 steers per pen. Cattle performance has been reported but feeding roasted soybeans resulted in improved gain and G:F compared to whole soybeans which were better than all other treatments. Dietary fat was 3.0, 2.9, and 3.9% for CON, SBM, and WDGS treatments which increased to 5.4% with 12% of either WSB or RSB and was increased further to 6.2% fat when 16% of either soybean treatment was fed. The objective of this study was to determine the impact of feeding different amounts and sources of fat on diet and fat digestibility. To determine fecal output, 2.5% zeolite clay was fed for 5 days prior to 3 days of pen surface fecal collections. Acid detergent insoluble ash (ADIA) was used as a marker and the zeolity clay was 86.4% ADIA. Dietary ingredients and fecal samples were composited by day and pen, and analyzed for ADIA, OM, and fat. Treatments were evaluated using proc mixed as both an unstructured treatment design using a protected F-test and the 2×2 factorial of either 12 or 16% inclusion of either WSB or RSB were tested. Digestibility of DM and fat were impacted by dietary treatment (P < 0.01). Cattle fed CON and WDGS were similar (P = 0.16) in DM digestibility but lower (P < 0.03) than cattle fed any of the soy treatments (SBM, WSB, or RSB). Fat digestibility was similar (P =0.79) between CON (89.5%) and SBM (89.3%) but lower (P < 0.07) than cattle fed WDGS (92.1%), 12% WSB (91.8%), 16% WSB (92.6%), or 16% RSB (91.4%). Cattle fed 12% RSB were intermediate for fat digestibility (90.4%). For the factorial, no interaction was observed for fat digestibility (P = 0.88). Feeding 12 or 16% whole or roasted soybeans did not impact fat digestion (P = 0.21). Roasting soybeans tended to slightly reduce fat digestibility (P =0.07) from 92.2% to 90.9%. In this study, feeding more fat in the diets with either whole or roasted soybeans did not decrease fat digestibility, but fat excretion did increase as fat intake increased.

Rourke, E., T. Lewis, M. Bausch, J. Miller, P. Loza and G. Erickson. 2026. Effect of Feeding Whole or Roasted Soybeans to Finishing Cattle on Fat Digestibility. ASAS Midwest Section Meeting. Abstract 11. https://doi.org/10.1093/jas/skag107.298