DRY MATTER YIELD, IN VITRO DIGESTIBILITY, PERCENT PROTEIN, AND MOISTURE OF CORN STOVER FOLLOWING GRAIN MATURITY

Abstract

Past research and practical experience have shown that the stover of corn (Zea mays L.) can be used successfully as a roughage and energy source for ruminant animals. The present paper describes three experiments designed to study agronomic aspects of stover utilization. Specifically, the objectives were: (1) to study the rate of moisture loss from stover before and after grain harvest; (2) to measure the variability among commercial hybrids in stover quality and yield; and (3) to examine the relationships between grain and stover yield, and between grain and stover moisture percentage. Averaged across hybrids, 38% of the above-ground dry weight of corn was stover, including stalk, leaf, husk, and shank. At grain maturity, all adapted commercial hybrids produced stover dry matter yields in excess of 4,500 kg/ha with an in vitro digestible dry matter (IVDDM) in excess of 52%. Lower yields of stover dry matter and stover IVDDM were evident for certain nonadapted, or nonrecommended hybrids. Within recommended hybrids there was a nonsignificant correlation between grain yield and stover yield. Percent IVDDM of the stover declined at a rate of 1.5%/wk following grain physiological maturity. Protein content of stover averaged 4.5% and was unaffected by hybrid or date of harvest. No relationship was evident among hybrids between percent stover moisture at harvest and percent grain moisture. The mean percent stover moisture, after adjustment by covariance to 30% grain moisture, was 57.8 with a standard deviation across hybrids of 11.4%. Stover dried at an average rate of 1.0 g water loss per 100 g fresh weight per day during the grain maturation period. Differences among hybrids in percent stover moisture at a common grain moisture were primarily a result of differences in the date at which stover began to dry below its initial moisture content of 80%. Grain harvest with a standard corn combine increased the drying rate of stover to approximately 1.5 g water per 100 g fresh weight per day during the period after grain maturity.