Silaging care saves costs

With ensiling losses up to 25% in some cases, and costs of big-bale silage ranging from £80-100t/DM and clamp at about £90t/DM, poor planning and silage wastage aren’t to be sniffed at this season.

And there is plenty farmers can be doing to reduce losses, according to ADAS sheep consultant Kate Philips, speaking at a recent EBLEX farm walk near Tewkesbury, Gloucestershire.

“Rising costs of concentrates mean it is essential producers make the most of forage, but care must be taken to prevent losses,” she said.

Planning when to cut is crucial because, as grass grows, the D-value and protein value decrease – within a week D-value could have dropped from 12MJ/kg to 8MJ/kg, said Ms Philips.

“But it’s not just about getting the correct height, it’s also about making sure sugars are at the right level. You need about 4% sugar to get good fermentation in silage, but often getting the right bacteria is not achieved.”

Silage additives add more of the right bacteria, lactobacillus planetarium, to grass, producing a favourable fermentation which stabilises the pH but, at a cost of between £1-1.50/t, it’s important to consider whether it’s going to maximise performance.

“Additives are extra costs, but since they enhance the fermentation and improve palatability, they are worth considering,” added Ms Philips.

Ensuring cutting height is correct to prevent soil contamination and spreading grass immediately to get a good wilt, leaving for 24hrs for clamp silage and 48hrs for big-bale crops will ensure less of the digestible leaf is lost. But it’s the wrapping stage where losses can occur.

“Bale wrapping is often where spoilage can happen, and this is why it’s important to keep in mind the cost of a bale at about £14.50/t. Wrapping at the site of storage helps keep bales intact and unwanted bacteria out.”

The number of layers to wrap is often up for debate and Ms Philips said it should be determined by the dry matter. “Lower DM bales need about four layers compared to high DM at six layers. Wrap colour can also influence quality, with trials suggesting green is better than black and white,” she said.

Silage analysis is often a forgotten feature in the sheep industry, but analysing silage quality determines how much concentrates to feed. Ms Philips encouraged producers to get an analysis done six weeks after making.

But even those getting an analysis done, may not act on what the results are saying. The key things to look out for are intake potential figure, DM, D-value, pH, crude protein, ammonia and NDF. Knowing pH silage quality allows changes to be made to concentrate levels.

“For a 70kg ewe expecting twins, if you had a D-value of 60, you would need to feed 110kg of silage and 30kg concentrates. This compares with a D-value of 65 – you could feed 125kg silage and only 20kg of compound. This saving of 10kg equals a saving a £1.90/ewe. Even with tight margins this makes a big difference,” said Ms Philips.

But silage analysis is only as good as the sample sent. For clamp silage, taking a core sample from the middle of the clamp will give a more representative sample. For bales, taking cores from middle of at least five bales will be sufficient.

Silage Analysis – ideal values

  • DM (%) >30
  • D-value (%DM) >62
  • Ph ≤4-5
  • Crude Protein (%) 10-16
  • Ammonia (% total N) <10
  • NDF (g/kg/DM) 450-550