Stover, made up of stalk, leaf, husk cover and cob is of lower quality than maize grain. Stover contains no starch, limited water soluble carbohydrates, low protein and is high in fibre (NDF).
As a maize crop matures, quality of stover falls. By the time the whole plant DM% reaches 40-42% DM or more, content of NDF and lignin increases (so NDFd – digestibility of NDF falls), water soluble carbohydrate content and MJME/kgDM are lower than for a less mature plant.

Quality of maize grain is high compared to maize stover. MJME is high, due to a high starch and low fibre (NDF) content. As maize plants mature, starch accumulation increases until the plant reaches physiological maturity (black line, or black layer). As the plant dries down, starch digestibility reduces.

Like stover, protein content of maize grain is low, typically lower than 10% DM.

As the ratio of stover to maize grain changes, so does the quality of maize silage. More grain means better overall quality of maize silage.