Step 2. Wilting

CTC Wilting Icon-01.png

Wilting increases the % dry matter and reduces losses from effluent.

It also means the silage will stabilise at a higher pH so less acid, hence sugars, will be required.

The problem is, as soon as grass is cut, sugars start declining because they are being used up by the plant, since it is still living, and by undesirable bacteria.

A higher DM will also inhibit undesirable clostridia bacteria.

Therefore, the aim should be to wilt as rapidly as possible to an ideal target DM of 28-32%, but no longer.

Independent Silage Expert, David Davies explains the key things to think about when wilting grass for silage making.

TOP TIP: Leaving grass to wilt also reduces haulage.


While a 24-hour wilt may be fine in some circumstances, it could be too long in good conditions. For example, cutting in the morning and achieving a rapid wilt could mean 28-32% DM is achieved that same afternoon.

By contrast, if you cut in the afternoon, although sugar content might be higher initially because the crop has been photosynthesising for more hours that day, you could be forced to wilt for a full 24 hours, so more of that sugar could be lost.

To reduce wilting time, make effective use of mower-conditioners and tedding. But make sure tedders and rakes are adjusted correctly to avoid hitting the ground and risking contamination with soil.

Wilting small.jpg

Multi-cut hints and tips

As with conventionally-made silage, the aim for multi-cut silage is still to wilt as rapidly as possible to 28-32% DM.

However, with multi-cut, the wilting time needed to reach 28-32% DM can be much shorter.

That's partly because the yield of individual cuts will be lighter (less bulk to lose water from), but also because younger grass contains more leaf and less stem material, and leaves lose moisture much faster.

That can be a real bonus in showery weather. But take care not to over-wilt. Make regular checks on dry matter levels.

If silage is made too dry, it becomes prone to losses through heating caused by aerobic spoilage.

Note: Multi-cut is sometimes likened to the Dutch system of making silage where they do make higher dry matters. But they are geared up for this, and often have narrow clamps, so can move across the face quicker to help reduce aerobic losses.

Volac and Germinal have developed a 10-point multi-cut grass silage checklist, designed to help you get the most from your grass silage making process.

If you cut at 11.5 ME and you have 1,000 tonnes of silage, it is the equivalent of 300,000 MJ of energy extra compared to cutting at 10.5 ME. This is approximately equivalent to 60,000 litres of milk.
— Dr David Davies, Independent Silage Consultant

Want to learn more? Take a look at the next step.