This study aimed to determine the minimum soybean meal (SBM) inclusion in diets with or without distillers dried grains with solubles (DDGS) to optimize growth performance and carcass characteristics in finishing pigs. For the early phase (Exp. 1), 4,080 pigs were used in a 28-d trial. Dietary treatments were arranged in a 2×4 factorial with main effects of DDGS (0 or 30%) and increasing SBM (low, low-medium, medium-high, and high). There were 34 pigs per pen and 15 pens per treatment. The diets without DDGS contained 17.5, 23.3, 29.1, or 34.9% SBM while diets with DDGS contained 3.9, 12.8, 21.8, or 30.6% SBM. For the late phase (Exp. 2), 3,984 pigs were used in a 28-d trial. Diets were also arranged in a 2×4 factorial with main effects of DDGS (0 or 15%) and SBM (low, low-medium, medium-high, and high). There were 30 to 34 pigs per pen and 15 pens per treatment. Diets without DDGS contained 6.5, 11.5, 16.4, or 21.3% SBM, while diets with DDGS contained 0, 6.4, 12.8, or 19.2% SBM. Following the 28-d growth study, pigs were marketed on a fixed weight basis across three marketing events, and carcass characteristics were collected. Between experiments, pigs were fed a common diet with 7.5% DDGS. In Exp. 1, a tendency (P=0.088) for a linear interaction between DDGS and SBM level was observed for ADG, where increasing SBM decreased ADG in diets with 30% DDGS but did not affect ADG in diets without DDGS. Pigs fed 30% DDGS had decreased (P≤ 0.01) ADFI and G:F. Increasing SBM, regardless of DDGS inclusion, decreased ADFI (linear, P=0.001) and increased G:F (linear, P=0.043). In Exp. 2, an interaction (linear, P≤0.05) between DDGS and SBM level was observed for ADG and ADFI, where increasing SBM reduced ADG and ADFI only in diets containing 15% DDGS. Pigs fed diets without DDGS had a tendency (P=0.094) for increased G:F compared to pigs fed 15% DDGS. Increasing SBM increased G:F (linear, P< 0.001) but did not affect final BW. Marginal DDGS × SBM interactions for percentage lean and loin depth (P≤0.10) were observed with increasing SBM improving these traits only in diets with 15% DDGS. Pigs fed diets without DDGS had increased (P< 0.05) HCW, carcass yield, and backfat depth. Increasing SBM decreased carcass yield (linear, P< 0.001) and backfat depth (quadratic, P=0.033) in diets with or without DDGS. In conclusion, 30% and 15% DDGS negatively affected ADG and G:F. Feeding 29.1% SBM without DDGS and 21.8% SBM with 30% DDGS in the early phase increased G:F without compromising ADG, while feeding 16.4% SBM without DDGS and 19.2% SBM with 15% DDGS in the late phase improved G:F and carcass characteristics

Giacomini, P., K. Gaffield, M. Tokach, J. DeRouchey, J. Gebhardt, J. Woodworth, C. Shull, O. Mendoza, A. Petry, M. Putman, A. Gaines and R. Boyd. 2025. Effects of increasing soybean meal in diets with or without distillers dried grains with solubles on growth performance and carcass characteristics of pigs in early and late-finishing phases. 2025 American Society of Animal Science Midwest Section meeting, Abstract 98.