Two experiments were conducted to evaluate replacing dried distillers grains with solubles (DDGS) with heat-treated soybean (TSBM) at increasing rates in forage-based diets on steer growth performance, nutrient flow, and digestibility. Experiment 1: 70 angus-based steers were utilized in a generalized randomized block design for an 85-d growing study at the NDSU Beef Cattle Research Complex. Experiment 2: five fistulated Jersey steers fitted with ruminal, duodenal, and ileal cannulas were utilized in a 4 × 5 row column design for 56 d to measure nutrient flow and digestibility. Diets were formulated to replace DDGS, included in the diet at 16% dry matter, with TSBM at 0 (TSBM0), 4 (TSBM4), 8 (TSBM8), and 12% (TSBM12) increments. Treatments had no effect on steer growth performance and residual carcass characteristics from the growing phase. Nitrogen, lysine, and available lysine total tract digestibility increased with increased TSBM inclusion however, post ruminal digestion decreased.