EFFECT OF HARVEST DATE ON YIELD, COMPOSITION, AND NUTRITIVE VALUE OF CORN STOVER AND DDGS

Efficient utilization of the non-grain portion of corn plant and distiller's grains for ruminants and the grain for ethanol will allow optimization of both food and fuel production. Corn stover can be effectively used as animal feed if it is collected before in-field dry-down. This study determined the yield and nutritive value of corn stover, distiller's dried grains with solubles (DDGS), and feed value enhanced stover (FVES) (a mixture of corn stover and DDGS) on different corn harvest dates, and determined the harvest time that maximizes whole-plant utilization. Corn and corn stover were harvested at different dates from 21 August to 23 November in 2009, and DDGS samples were produced from the corn samples collected at different harvest dates by dry grind fermentation. From 21 August to 23 November, dry matter yield of the stalk and leaf fraction and the cob decreased by 37.4% and 9.8%, respectively. During the same time period, neutral detergent fiber, acid detergent fiber, and lignin concentrations in the stalk and leaf fraction increased by 16.8, 12.7, and 1.0 percentage points, respectively, while crude protein concentrations decreased by 4.1 percentage points. For FVES, both the highest dry matter yield and the highest total digestible nutrient concentration were reached when corn just reached physiological maturity. Corn and corn stover can be harvested at the corn physiological maturity stage for maximum dry matter yield and optimum nutrient quality of FVES for ruminants, leaving more corn for ethanol production.