Farmers are being encouraged to test first-cut silage before feed-out amid reports of high levels of ash in some silage crops.

Liz Homer, ruminant technical development manager at Trouw Nutrition, says that while average ash levels are looking similar to last year, in some areas they are higher than normal, which could pose a cause for concern.

"Silage samples are extremely varied this year so it's important to compare your own silage analysis to previous years, and analyse forages in the clamp regularly to check for any changes. This could mean that you need to rebalance your ration and rethink mineral supplementation in more detail," says Ms Homer.

Anwen Jones, regional business manager for Wales at Lallemand Animal Nutrition, says data from the company's silage analysis service shows a greater number of first cut silage samples received this year have ash levels higher than 7%, and even above 10%, in comparison to silage sample results from the same period last year.

"If you cut during the wet spell in May, take a close look at your ash results before feeding first cut, as there could be an increased risk of soil contamination in your silage," says Mrs Jones.

She says this is a cause for concern as any level above 6-7% is an indication of soil contamination in grass silage. If your first cut silage is above these levels, Mrs Jones says there are simple practices that can be taken to mitigate the impact on cow health.

"Ensure all ensiling equipment is as clean as possible before cutting at the correct height can help prevent contamination, however many of this year's first cuts were harvested during less than ideal ground conditions - with soil contamination an inevitable result," she says.

To manage the risk of contaminated silage, Mrs Jones recommends testing silage to assess its ash content, and supplementing animals with products that contain live and dead yeast components, such as Levucell SC Toxisorb.

"Using a rumen-specific live yeast in combination with inactive yeast components such as yeast cell walls will not only favour a positive microbial balance in the rumen and aid digestive resilience to contaminated feed, but it will also improve fibre and total diet digestion improving feed efficiency and milk performance," says Mrs Jones.

Her other tips for managing contaminated silage are:

• Do not be tempted to feed highly contaminated, or visibly deteriorating silage to any animals as this can cause both short- and long-term issues ranging from reduced feed intake to diarrhoea and in extreme circumstances even death
• Dilute suspected low level contaminated silage with other cuts of forages to minimise overall dietary ash content
• Ensure high levels of hygiene throughout the feeding regime to reduce the risk of further microbial contamination by regularly cleaning troughs, keeping feed wagons clean and keeping vermin and birds away from feed