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How to make the best grass silage possible


When fed correctly, good quality silage is the most cost-effective feed source for dairy and beef systems, and it supports both animal health and production.

In dairy herds, feeding good quality silage not only helps maximise milk yield, but the breakdown of the fibre fraction of silage in the rumen is strongly linked to acetic acid production – an important precursor of milk fat.

In beef systems, feeding a highly digestible silage will encourage dry matter intake (DMI), which in turn can improve rumen health, feed efficiency and average daily gain (ADG).

Regardless of whether you are producing silage for dairy cows or beef cattle, achieving incremental improvements in silage quality will pay off.

In particular, it can make a huge difference to the level of purchased feeds that are required, and in some systems, displace purchased feeds altogether.

How do you produce high-quality silage?

While there are some factors which impact silage quality that are out of your control – such as the weather – careful planning and attention to detail can go a long way towards producing the best silage possible. Following an Opticut system can help achieve this.

Opticut takes a planned approach to maximise the quality and quantity of grass silage throughout the growing season to fit the feeding scenarios and forage balance required for any particular farm.

There are three key elements to the system. These include: 1. Pre-cut testing to ensure the crop is at the optimum stage for cutting.

2. Correct management of the silage-making process.

3. Use of a crop- and condition-specific inoculant to improve nutrient retention and reduce losses from aerobic instability.

Should I sacrifice some silage quality to get a higher quantity?

It can be tempting to leave grass to bulk up to increase the quantity of forage harvested, however this comes at the expense of fibre digestibility and will lower production potential from forage.

Additionally, if measured across the season, it is often a false economy, as you typically get a greater quantity of silage from more, higher quality, cuts than fewer, larger cuts.

The cost of supplementing poorer quality silage with concentrates will also be greater than finding additional sources of fibre, so producing enough high quality silage should be the primary goal.

If lower quality forages are needed in your feeding plan, and grass availability and clamp storage capacity permits, cuts of lower quality silage could subsequently be produced.

When is the right time to cut grass for silage?

Pre-cut grass testing is the best way to decide when to cut, and will assess nitrate levels, NDF and sugar content.

You should start pre-cut grass sampling three weeks before the date you cut silage last year, as there will always be yearly variation in grass growth. Read more about pre-cut testing here.

How long should you wilt grass silage for?

Spreading/tedding should be done within the first two hours after cutting as optimum wilting occurs during this time.

Grass should be wilted until it reaches 30% DM, which is the ideal target. It is acceptable to harvest at a DM above 28%, however if it is below 28% it is better to leave it to wilt a little longer.

Grass should never be wilted for more than 24 hours. After this point, DM losses start to increase because the protein is broken down as the grass continues to respire.

Should I use a silage inoculant?

Applying a crop- and condition-specific silage inoculant, also sometimes referred to as a silage additive, will help promote rapid fermentation and reduce aerobic spoilage at feed-out.

The enzymes in an inoculant will break bonds in the fibre bundles, releasing sugars to fuel the fermentation process, which can have a positive effect on fibre digestibility. The MAGNIVA range of grass silage inoculants have been specifically formulated for the various challenges that you may face. They contain a blend of specific patented bacteria and enzymes that have been proven to improve silage quality, palatability, and reduce total DM losses of valuable crops.

How much should you roll grass silage when filling the clamp?

When filling the clamp with grass, or indeed any crop for ensiling, never create layers that are more than 20cm thick.

It can be difficult to know how much to compact grass in the clamp, especially during the ensiling process, but a good rule of thumb is the drier the crop, the more it needs to be compacted.

If possible, avoid using dual or double tyres and consider filling tractor tyres with water or sand to increase their weight, to help increase compaction per square metre of clamp surface.

For more helpful advice on making good quality grass silage, request a copy of our Forward with Fibre guide here.

Published Jun 27, 2023 | Updated Feb 1, 2024