Effect of Maturation on Composition and In Vitro Dry Matter Digestibility of Corn Plant Parts

Corn (Zea mays L.) plants from four plots were harvested at 2-wk intervals from September 9, 1975, to December 9, 1975; separated into grain, cob, husk, leaf, and stalk; and analyzed for dry matter, crude protein, cell wall, and in vitro digestibility of dry matter. Green weight yields of all plant parts except grain decreased with advancing maturity during sampling. Percentage of dry matter increased for all parts while total dry matter per hectare increased until plant dry matter reached 35% and then decreased. Grain as a percentage of the total dry matter of plant increased to 50, then remained relatively constant. Cob, husk, leaf, and stalk made up smaller percentages of the plant dry matter as it matured. Crude protein content of leaves declined but remained fairly constant in other plant parts through this sampling period. The percentage of cell wall increased and in vitro digestibility of dry matter decreased in all plant parts except grain which remained fairly constant with maturation. Increases in grain content offset decreases in digestibilities of other plant parts until the grain was physiologically mature; then total plant digestibility decreased. Livestock producers who plan to feed stover should harvest the stover simultaneously or as soon after grain harvest as practical.