Corn is the most productive grass grown in Iowa with dry matter yields often exceeding 6 t/a. Harvesting corn by grazing can provide abundant pasture in mid- to late-summer when pastures in southern Iowa normally make little growth. This approach eliminates harvesting, drying, storage, and transportation costs associated with marketing the grain and leaves almost all of the surplus or waste nutrients in the field. Objectives of this project were to measure animal performance when standing corn crop was the sole feed source for pregnant diary heifers and to increase our understanding of the management practices necessary to optimize the use of this feed source.