Wilting is one of the most important steps when making high quality silage - wilting increases the dry matter (DM) percentage of the grass. This has an influence on silage quality and reduces the quantity of effluent produced. The target should be to wilt the silage to a DM of between 28% and 32%. Drying it more than this will not give any improvement in animal performance. Wilting makes the sugars more concentrated in the grass, allowing the resulting silage to stabilse at a higher pH; this means a lot less acid or inoculant is required to preserve the crop.

Wilting silage

Farmers should aim to wilt the grass as quickly as possible post mowing, in order to limit sugar losses - approximately 6% of the sugars present in grass can be lost during a 24 to 36-hour wilting period. Better quality silage will improve silage intakes, and drier crops require less acid to become stable – there are benefits of that in fermentation. Mowing when conditions are dry is best, and before cutting, you would like the sward to be above 20% DM. If it is dry when you are cutting and dry when you are wilting; this will be ideal for mowing and picking up the sward on the same day, provided it is cut when the dew has lifted off the grass. If it is wet when you are cutting and and it dries afterwards, you can overcome it; but if it’s wet when you’re cutting and wet when you are wilting, it can be very challenging. Once grass is cut, the energy supply is cut-off. The grass is dying, but carries on respiring, burning up nutrients and protein until it is taken down to a stable pH – so the longer grass is left in the field, the more nutrients that are lost.