Is wilting grass silage really important?

Wilting is an important step when making grass silage as it increases the Dry Matter (DM) percentage and reduces the quantity of effluent produced.

Ideally, farmers should aim to wilt their silage to a DM of 28-32% – anything above this will have no benefit on animal performance.

Drying grass, through wilting, makes the sugars more concentrated in the grass, allowing the resulting silage to stabilse at a higher pH. This means that less acid or inoculant is required to preserve the crop.

As part of Cut to Clamp, a new initiative from Volac which aims to help farmers make consistently better silage, we take a look at the important steps to get right when wilting your silage.

The importance of a rapid wilt

Weather plays a key role and farmers should avoid cutting until the weather conditions allow the entire process to be completed – this includes cutting, wilting and harvesting.

In ideal conditions, farmers should aim to wilt the grass as quickly as possible to limit sugar losses post-cutting.

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.

This is important as approximately 6% of the sugars present in grass can be lost during a 24-36-hour wilting period.

Therefore, the aim should be to wilt as rapidly as possible to an ideal target DM of 28-32%.

Fella tedder

How long should I wilt?

Farmers have two options when it comes to wilting a grass crop for silage.

The first involves wilting the grass rapidly by mowing and harvesting the crop on the same day. For this system, farmers should cut the crop once the dew has lifted and collect it later the same evening.

This method has the potential to increase the amount of sugars present in the grass crop, but only if the weather conditions allow for a rapid wilt.

Or farmers could opt to wilt the crop for 24 hours. Under this method, the crop should be cut in the afternoon when the sugar content of the grass is at its highest.

However, there is a risk of the crop becoming too dry with the longer wilting period, which could have a negative impact on the aerobic stability of the silage at feed-out.

Tedding and conditioning

To reduce wilting time, farmers should make effective use of mower-conditioners and tedders to spread the crop.

However, tedders and rakes must be adjusted correctly to avoid contaminating the crop with soil.

If soil contamination occurs, it may have a negative impact on the preservation of the crop and, in turn, the feeding value of the silage.

Tedded swards wilted for more than 24 hours may become excessively dry and so farmers must monitor the Dry Matter content of the grass to avoid this from occurring.

Research has shown that excessively dry silage will not improve animal performance and may have poor aerobic stability at feed-out.

Silage, Summer, Weather, Grass

It is also advisable to row up immediately prior to picking up the crop with the forage harvester or wagon.

This post is sponsored by Volac, as part of its new Cut to Clamp initiative which aims to raise the profile of good silage as a vital part of modern farming. For more information on the Cut to Clamp initiative click here

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