Forage Maize - Silage Quality

Key silage quality characteristics:

  • Dry matter (DM) content
  • Energy content
  • Starch Content
  • Digestibility (‘D’ value)

Dry Matter content

The dry matter of maize silage should fall within an optimum range, ideally 28% to 32% dry matter, referred to as the harvest window. Varieties with a wide harvest window are desirable as they are more flexible to grow and harvest. A significant factor in dry matter content, is the ratio of cob:stover, and the stay-green ability of the plant.

Energy content

Increasingly higher levels of maize are being fed to stock. Dry matter or voluntary intake of maize silage has become a limiting factor in stock performance. †As a result the total energy content of the silage is valued more than total yield, with variety choice now having more emphasis on feed value, rather than exclusively on yield.

Starch content

Variety selection can be influenced by starch content and is dependent on the level of maize to be included in the ration. For low to mid maize feeding, selecting a high starch variety is preferable. For higher maize feeding regimes, varieties with balanced starch content between 30 – 32% are of greater importance, to avoid excessive starch, thus avoiding acidosis and poor rumen function.


The digestibility or ‘D’ value of maize silage is important for stock palatability and rumen degradation of the silage. Varieties with high ‘D’ value are preferable and offer greater milk output. Stay green varieties retain high digestibility closer to harvest.