Influence of Corn Particle Size on Steer Performance and Carcass Characteristics When Fed Diets with Moderate Inclusions of Wet Distillers Grains plus Solubles

and Implications A large pen study was conducted with a commercial feedlot to investigate the influence of corn particle size on performance of steers fed diets containing 35% (DM basis) wet distillers grains plus solubles (WDGS). Feedlot cattle in the Midwest are often fed distillers grains from ethanol production that are low in starch. Therefore, this study was designed to evaluate a practical question asked by producers if feeding moderate levels of WDGS would reduce the acidosis risk and allow fine grinding of corn to improve cattle performance. While fine grinding of corn did not improve performance compared to cattle fed a more traditional particle size of corn, starch digestibility of cattle fed finely ground corn was more favorable. Introduction Decreasing particle size of corn increases starch availability to the animal, but corn ground too finely often results in rapid fermentation in the rumen leading to acidosis. Starch comprises nearly two-thirds of the nutrients in the corn kernel and is the primary substrate for alcohol fermentation during the ethanol production process. Therefore, the remaining co-product is low in starch (typically less than 5% starch DM basis). While previous research with finely ground corn has been less successful due to acidosis, we hypothesized that feeding moderate amounts of distillers grains would lower acidosis risk, and reduced corn particle size would increased rumen starch availability allowing for improved cattle performance.