The concentrations of protein, fiber, energy, and fat depend on the maturity of the soybeans when harvested. As soybeans mature between those two stages, protein remains constant, NDF concentrations decrease and fat content increases. The composition data are from hand harvested plants. Soybean hay is extremely difficult to make. The leaves dry quickly and shatter during hay making and the hay is extremely dusty.
Soybeans also are difficult to ensile.
The silage and may have a high pH and may allow the growth of molds and other deleterious microorganisms. The best approach to using soybeans as a forage is to mix them with corn plants during silo filling. The corn provides soluble carbohydrates for the bacteria and dilutes the fat in the soybeans. A mixture of about 1 part corn and 1 part soybean works well. A higher ratio of corn to soybeans will not be detrimental but avoid using more than 1 part soybeans to 1 part corn.