Increased silage spoilage risk from field aftermaths in the uk

UK dairy farmers are advised to remove aftermath from silage fields or run the risk of significant aerobic spoilage in the conserved forage they make this year.

“Once again the UK winter has been extremely mild and grass has just kept growing,” says forage consultant Dr David Davies.

“December 2015 was the warmest December since records began in 1910, with an average temperature of 7.9°C – making it feel more like April than early winter. It was also the wettest month in the UK for more than a century. As a result, there’s a lot of grass aftermath about, but plenty of wet, dead material is caught up with it too that’s likely to contain high levels of yeasts and fungi. And more rainfall over the next few weeks will only increase soil splash up to the leaves, increasing the level of undesirable microbes still further”.

Consequently, the threat of mould growth in forage clamps and in other stored feeds – and associated mycotoxin production – will only get worse if mild temperatures and significant rainfall continue to the end of the winter.

The Alltech Mycotoxin Management team are advising farmers to remove the aftermath if at all possible.

Dr Davies adds “Many dairy farmers don’t like taking sheep on tack, but these grazers really are the best animals for cleaning up the sward in the winter. Essentially, there are two options available. Either leave the aftermath – which means you run the risk of producing poor quality silage – or remove it, either by mowing it off and wasting it, or bring the sheep in.”

If neither option is practical, many farmers will have to focus on excellent clamp management this year, as compaction of grass in the clamp is absolutely crucial.

“When clamping silage to reduce the risk of spoilage and potential mycotoxin contamination, the aim is to remove as much air from the grass as quickly as possible,” advises Emma Millar from the Alltech Mycotoxin Management team.

“Fill the clamp in layers no more than 15cm deep at a time and compact as you go. Your target should be 750 kg of fresh material per m³ (c. 250kg DM). Unfortunately, most farms are only reaching 650 kg per m³ or less, which means too much oxygen is left with the grass, increasing the chance of aerobic spoilage and moulds, and then potential mycotoxin contamination,” she says.

Farmers with a lot of aftermath who are concerned about the risk of aerobic spoilage must use an appropriate silage additive.

Ideally use a homo-fermentative inoculant, plus a chemical additive, or a chemical (salt) alone. The inoculant will improve the fermentation and the additional salt reduces aerobic spoilage. This will help stabilise the clamp.

Other tips to mitigate potential aerobic spoilage risks when silage making:

• Mow grass when it is dry
• Aim for a stubble height of 7-10cm
• Spread the crop immediately after mowing to encourage wilting
• Don’t leave a thick, dense sward – this is the perfect environment for mould

If you’d like to talk to a member of the Alltech UK Mycotoxin Management team, we’d love to hear from you. Simply use the Contact Us form here.