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

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Abstract
Corn (Zea mays L.) plants from 4 plots were harvested at 2 wk intervals from Sept. 9, 1975, - Dec. 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 wt yields of all plant parts except grain decreased with advancing maturity during sampleing. Percentage of dry matter increased for all parts while total dry matter per ha 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 decrease 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.