Making the most of first cut

Published 24 May 13

Making the most of first cut

Following a very poor spring we are finally approaching silage time for most farmers. With silage stocks on many farms exhausted, achieving a good crop of high quality first cut silage has never been more important, says Debbie McConnell, DairyCo R&D Manager.


  • Spending a little time now preparing for silage will help ensure a good quality feeding forage during the winter months. It is important to remember to:
  • Make sure the silage clamps are clean with no moulds or rotting silage left behind
  • Ensure a good drainage system is in place to allow effluent to move out of the clamp preventing spoilage at the base of the clamp
  • Make sure the clamp walls are impermeable to air; oxygen will hinder the fermentation process reducing silage quality
  • If you haven't already, walk the fields to remove any large stones or obstacles which could damage silage equipment - this can be costly in terms of both time and money.
  • Grass sampling

In addition to making the clamps ready, it is also essential to sample your silage before cutting. Atypical conditions this year may have resulted in a large proportion of nitrogen and sulphur being leached out of the soil in the wet weather. Testing your grass will give you an indication of what you should expect from your forage and allows you to address any nutrient deficiencies in the soil after first cut silage.

Grass sampling is also important if your fertiliser was applied late this year. Applications of nitrogen close to cutting can cause anincrease in plant nitrate concentration which impacts on silage quality. While nitrogen increases crude protein levels in the plant, very high levels of nitrate prevent the pH of the silage from dropping adequately during the fermentation processes, resulting in poorer quality forage. Results from N.I. suggest that nitrate concentrations below 0.1% (or 1,000ppm) should not impact on the ensiling process.

Likewise sampling is important if you wish to use an inoculant on your crop. Silage additives can be an effective way of enhancingthe fermentation process and the quality of the feed produced. Studies at AFBI, Hillsborough, have shown that, averaged over 11 studies, the milk yield benefit from using an inoculant was 0.54 litres/cow/day, with improved milk quality.

As there are a number of different additives available for grass silage, each with different functions, it is important to have an indication of the characteristics of the crop to be ensiled, e.g. DM, digestibility, buffering capacity etc. This will ensure that you can match the additive to the specific requirements of your crop.

Minimising losses

Poor grass growth in the last few months has meant that the yield of grass on many of the silage fields is lower than would be expected for first cut, so it is crucial to try and minimise any losses both in the field and the clamp. Losses of silage DM yield between harvesting, ensiling and feeding out under good management conditions are estimated to be as high as 20% with between 5% and 10% of losses attributed to harvesting and ensiling alone. High losses at silage time significantly increase the cost of the silage you produce, an increase in loss rate from 15% to 40%, increases the cost per tonne of silage DM from £131 to £175.

To minimise losses, consider the following:

Get a good wilt. In dry sunny conditions wilting can increase DM by 1-2% per hour

Good consolidation is the clamp is key to removing any oxygen and ensuring the fermentation process gets underway quickly. Fill the clamp evenly with regular rolling of layers of no more than 20cm

Reduce contamination of the silage. When picking up, keep the reel high enough to avoid any soil contamination. At the clamp keep the apron clean by avoiding dirty wheelings where grass will be tipped

Pull the sheet over the top of the clamp at the end of each day; this will prevent any air entering

Avoid rolling before the next day's filling (this will draw air in)

Cover and seal the clamp efficiently - folding side sheeting in before the top sheet goes on will help seal the clamp. Covering the whole area with heavy covers, straw or tyres will reduce any wastage at the top of the clamp.

More information on silage making can be found in chapters 8 and 9 of