This study aimed to examine the nutraceutical effects of increasing soybean meal (SBM) with or without distillers dried grains with solubles (DDGS) on acute phase proteins and oxidative biomarkers in grow-finish pigs. C-reactive protein (CRP) and haptoglobin, involved in complement activation and pathogen clearance, and total antioxidant capacity (TAC) and malondialdehyde, which reflect oxidative status, were examined. In Exp. 1, a total of 120 pens with 34 pigs per pen (n=4,080 pigs; initial BW 34 kg) were used in a 28-d trial with a 2×4 factorial arrangement. Main effects included DDGS (0 or 30%) and a titration of SBM (low, low-medium, medium-high, and high). Diets formulated without DDGS contained 17.5, 23.3, 29.1, or 34.9% SBM, whereas diets with DDGS included 3.9, 12.8, 21.8, or 30.6% SBM, respectively. Following Exp. 1, a washout period occurred from 64 to 84 kg, during which pigs were fed a common diet with 7.5% DDGS. After the washout, 3,984 pigs were reassigned to a 2×4 factorial in Exp. 2, with main effects of DDGS (0 or 15%) and SBM (low to high), and 30 to 34 pigs per pen (15 pens/treatment). In Exp. 2, 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, respectively. On d 28 of each experiment, serum and plasma were collected via jugular venipuncture from 3 randomly selected pigs per pen for biomarker measurements. Data were analyzed using a linear mixed model, with pig nested in pen as the experimental unit. Fixed main effects, along with linear and quadratic contrasts for increasing SBM levels, and their interactions with DDGS, were assessed. Across both growth periods, plasma malondialdehyde did not differ among dietary treatments (P>0.1). Inclusion of 30% DDGS in Exp. 1 decreased serum haptoglobin concentrations, but increased CRP (P< 0.05). In Exp. 1, irrespective of DDGS inclusion, increasing SBM linearly elevated haptoglobin concentrations (linear, P=0.1). There was a tendency for a quadratic response for CRP in Exp. 1 with increasing SBM regardless of DDGS supplementation (quadratic, P=0.06). There was a tendency for a linear interaction between DDGS and SBM levels for TAC in Exp. 1 (P=0.052). Whereas, in the absence of DDGS, increasing SBM increased TAC, but in the presence of DDGS it decreased with increasing SBM. In Exp. 2, haptoglobin and TAC did not differ among dietary treatments (P>0.1). In Exp. 2, increasing SBM resulted in a quadratic response in CRP when DDGS was included, but this effect was not observed without DDGS (P=0.041). These results suggest a complex relationship between SBM nutraceutical effects and DDGS supplementation in grow-finish diets.

Putnam, M., H. Miller, R. Self, P. Giacomini, R. Goodband, K. Gaffield, J. Woodworth,  A. Gaines, C. Shull, O. Mendoza and A. Petry. 2025. Oxidative status and acute phase protein biomarkers are differentially altered in commercial grower and finisher pigs fed increasing soybean meal with or without distillers dried grains with solubles. 2025 American Society of Animal Science Midwest Section meeting, Abstract 103.