Part 1, Section 4: Corn
Corn
TYPES
Brown midrib corn
Brown midrib plants are characterized by a brown pigmentation in the leaf midrib at the V4 to V6 stage and a light brown coloration of the pith after tasselling. Brown midrib hybrid contains a gene (bm3) that causes a lower lignin content in corn plant tissue. Lignin is a relatively indigestible compound that limits the digestibility of the fiber in the corn plant. The reduced lignin in brown midrib corn results in silage with fiber that is more digestible than normal corn.
Animal feeding trials have shown about 10 percent greater intake and increased mild production with brown midrib silage, as compared to normal silage. Brown midrib lines frequently have been low yielding, however, and have had poor standability if left for grain production. Although recently released brown midrib hybrids have improved these features, they still are lower than those of comparable normal hybrids. In our trials, brown midrib lines have yielded about 10 to 15 percent lower than conventional hybrids in fields where they are best adapted, but have yielded 15 to 25 percent less than conventional hybrids where European corn borers, gray leaf spot and other pest problems are present. When considering a brown midrib corn planting, growers should weigh the potential for improved milk or animal gains, which can be significant, against the higher production costs and lower yields per acre.