June 9th - 2021

Mould and mycotoxin warning for livestock farmers during silage feed-out

Despite a favourable silage-making season, livestock farmers will still need to be on top of their game this winter to reduce the effect of moulds and mycotoxins on forage quality during silage feed-out.

That’s the advice from Silostop's technical team and Professor Mike Wilkinson of Nottingham University, who stress that correct winter clamp management is vital to maintaining the quality and nutritional value of silage this winter.

The most important aspect of silo management is to minimise oxygen ingress during the storage period to reduce spoilage and loss of nutrients from the outer areas, Professor Wilkinson explains. This is especially true at the shoulders and margins of bunkers and clamps where the density of the silage is lower due to insufficient consolidation.

“As soon as this silage is exposed to air during feed-out, spoilage will begin and the pH of the crop will rise. The silage will heat up and begin to rot as moulds develop”.

“This process goes hand-in-hand with the production of mycotoxins which make the silage less palatable and present a stress danger which can negatively effect milk yield and quality, as well as having a detrimental effect on cow fertility.”

In addition to poor consolidation, the main risk factor in mould and mycotoxin development is air ingress through inadequate silage sheeting explains Ms Hitchman, Silostop’s Ruminant Forage Specialist.

“It is important to understand that not all silage sheets are 100% effective in keeping air out of the ensiled crop,” Ms Hitchman stresses. “Modern products, such as Silostop’s Orange and Black oxygen barrier films are up to 100 times more effective at reducing oxygen ingress than conventional plastic sheets and can reduce dry matter losses in the top metre of the clamp by up to 50% as well as increasing the aerobic stability of the top layer during feed-out by around 2.5 days.”

Maintaining silage quality throughout the winter is as important to efficient feed conversion as the ensiling process itself, Ms Hitchman suggests. “By following a few simple guidelines, livestock farmers can effectively limit silage spoilage during the winter and maintain the nutritional value of their ensiled forage.”

In addition to using an effective oxygen barrier sheet Ms Hitchman also offers the following advice: “Pull back only enough of the top sheet to expose silage for that day’s ration and minimise disturbance to the exposed silage face by using a well maintained and sharp shear grab or cutter to remove silage from the clamp. This will leave a clean face, reduce air ingress into the clamp and therefore limit excessive surface spoilage.”

Ms Hitchman also advises farmers to feed out from across the full width of the clamp within as few days as possible: The amount of time it takes for the exposed forage to degrade will vary according to silage quality, density, dry matter and prevailing environmental conditions, she adds. “Keeping the amount of exposed silage to a minimum, and using it as quickly as possible, will reduce heat build up within the crop and minimise mycotoxin contamination”.

Ms Hitchman also warns against re-covering the face of the clamp. “Covering the clamp face once aerobic spoilage has started will trap heat within a micro-climate and exacerbate the problem,” she states. “Instead it is much better to leave the face open and to keep the whole clamp area tidy and free of spoiled silage.”

Professor Wilkinson also warns that once aerobic deterioration has taken hold there is little that can be done. The first sign of any problem may be reduced feed intake as the ensiled crop becomes less palatable. This will result in reduced milk yield and poor fertility, as well as other herd health issues. “By the time moulds have started to grow it will be too late to save the crop. The only realistic course of action is to inspect each open clamp for signs of heating by digging 20-30cms into the clamp and to feed out any affected forage as quickly as possible. A mycotoxin binder in the diet should provide some protection, but in the worst cases, it may be wiser to throw the crop away.”

Professor Wilkinson concludes by recommending that farms where large quantities of silage are wasted year after year may need to have their clamps redesigned. “Excessively wide clamps can be made narrower by adding a central line of portable concrete barriers so that exposed silage at the face of the clamp is reduced and the feed-out progression rate is more rapid– that is an effective way of reducing the risk of moulds and mycotoxins having a negative impact on silage quality.”

Professor Mike Wilkinson