Benefits of Pre-Cut Testing Fresh Grass to Determine Silage Quality

Pre-cut testing of fresh grass

With all this dry weather, first cut is fast approaching but is it time yet? Mark Tucker, our Forage Specialist has taken some time to explain the importance of pre-cut testing and what this actually means in order to get the very best from your silage – especially the first cut.

Watch the video below:

What is pre-cut testing?

It analyses dry matter, protein, sugar levels, MEs, nitrate levels and NDF levels. A sample from the field is taken, posted off and the results are usually back within a day.

We usually suggest taking the sample from your worse-case scenario field. This is probably the field that has had the most slurry applied, was fertilised at the latest point and so is the field with high nitrate levels.

That means the grass won’t have had the time to turn the nitrogen that was applied into protein. You will need to wilt that grass for longer to take the nitrate levels out if they are high.

While we understand that when dry weather comes, you often don’t have much choice as to when you cut but with the first cut being between 6 – 8 tonnes per acre, it is important to know what you’re dealing with before you actually put it in the clamp.

Why is pre-cut testing important?

Every day later than the optimum of grass that you cut, you can potentially lose one ‘D’/day.

What does that mean? One ‘D’ equates to 0.16 of an ME. The maximum ME you’re likely to get from a perennial rye grass when at its optimum, is between 12.4 and 12.8.

If the max is 12.8, you’ll never get clamp silage above 12. The reason for this is as soon as you cut the grass, it starts declining in quality, so if you’re not starting from a high base, you’ll never achieve what you want in the clamp.
One ‘D’ a day if you’re seven days late in cutting the grass, equates to one ME. Most silage that we analyse is between 10.6 and 11.2 ME and this is because it has been left too late before cutting.


Protein levels

The optimum level of protein in the clamp is 15 – 16% but generally when we get analysis back, it’s between 13 – 14%.


  • Add clover to the ley using red clover leys
  • Use more nitrogen or more effective nitrogen that doesn’t leach

NDF levels

The main thing to be aware of is that if the levels are between 38 – 40% on the chart, that would mean 15-20% of your crop is heading and the rest of the crop would be at optimum stage to cut (with all this dry weather, we’re probably at this stage now).


Mark’s advice

Cut what’s there, slurry, fertilise and then wait for the rain. It’s worth sacrificing a bit of 1st cut yield for increased quality, which in turn should give you a much better second cut that delivers on both yield and quality! Although this isn’t always a popular option due to harvesting costs, it’s the quality that increases cow performance and subsequently increases milk and meat yields on-farm and that is one of the main things you should be striving for!

How to pre-cut test your fresh grass

Please contact your local CMC Representative who will arrange for a pre-cut test to be taken of suitable fields ensuring that you are as informed as possible when making the important decision of whether to cut or not. After all, forage comprises at least 50% of a cow’s diet and it is vital that we make it as good as we can!

Mark Tucker

Mark has extensive knowledge in forage production and quality. He is fully focused on treating every single farm differently and creating a specific plan based on the needs of the farming enterprise. Which enables him to maximise potential from the farm, he employs a back to basics theory in which he removes the potential pitfalls and tries to improve grassland management systems to increase production on farm from home grown forages.