Abstract This experiment was conducted to determine the dose-response effects of a modified corn protein product (MCP; Cargill Starches, Sweeteners, initially 5.7 ± 0.02 kg) were used in a 42-day growth study. Pigs were weaned at approximately 18 d and placed in pens of light pigs and pens of heavy pigs, then allotted to 1 of 4 dietary treatments in a generalized randomized block design. There were 5 pigs per pen and 16 pens per treatment across 2 barns. Dietary treatments consisted of 0, 7.5, 10.0, and 12.5% MCP in phase 1 and 0, 2.5, 5.0, and 7.0% MCP in phase 2 diets. Modified corn protein replaced enzymatically treated soybean meal, conventional soybean meal (SBM), and feed-grade amino acids in the control diet. Treatment diets were balanced for amino acids and minerals, but not energy, and fed in two dietary phases from d 0 to 10 and d 10 to 24, respectively, followed by a common phase 3 corn-SBM-based diet that did not contain MCP and fed for the remainder of the trial. On d 10 and 20, fecal samples were collected from the same three randomly selected pigs in each pen to determine fecal dry matter (DM). Data were analyzed using a linear mixed model using the GLIMMIX procedure of SAS (version 9.4; Cary, NC). Treatment and weight block were included in the model as fixed effects, and room was included as a random intercept. Preplanned contrasts were used to determine the linear and quadratic effects of increasing MCP. Fecal DM data were analyzed using repeated measures with pen included as a random intercept to account for subsampling. From d 0 to 10, ADG and d 10 BW decreased (quadratic, P 0.05), and G:F decreased (linear, P = 0.002) as MCP increased with the largest difference occurring when MCP increased from 10.0 to 12.5%. From d 10 to 24, ADG (quadratic, P = 0.086) and ADFI (quadratic, P = 0.023) increased then decreased as MCP increased with the best performance observed at 2.5% MCP. Overall (d0 to 42), there were no ADG or ADFI effects observed, but pigs fed increasing MCP had decreased (linear, P = 0.034) G:F. Fecal DM was not affected by dietary treatment on d 10, but increased and then decreased on d 20 (quadratic, P = 0.016) as MCP increased, with the greatest DM observed in pigs fed 5% MCP. In summary, increasing MCP in nursery diets had no overall effects on ADG or ADFI, but decreased G:F, which reflects the decrease in dietary energy as MCP increased.
Knoy et al. (Wed,) studied this question.