How to minimise mycotoxin risk when making silage

When making silage for livestock, farmers are being urged to focus on the process to minimise the threat of moulds and potential multiple mycotoxin contamination in their conserved forage. For good quality and quantity of silage, farmers are advised to cut and ensile grass correctly to minimise the risk of aerobic deterioration, mould development and multiple mycotoxin contamination.

Farmers are advised to base their mowing on current soil and crop conditions. “Mow when the grass is dry. If your sward is open or there is a lot of dead material in the base of the grass because of lodging or aftermath from last autumn perhaps, increase your cutting height to 7.5 - 10 cm,” advised Dr. David Davies of Silage Solutions, an independent British silage consultancy agency. “The main rational behind this is moulds such as penicillium live on low-lying dead and decaying plant material. Spread the cut grass to encourage a rapid wilt, too, because wilting has a significant depressing effect on grass microbial composition.”

However, Davies stresses that good compaction of the crop in the clamp is the most important step farmers can take this year. “Oxygen is the Achilles’ heel of silage production, and the key objective is to minimise the extent of aerobic spoilage in your clamp,” Davies advised.

Compacting even layers of grass no more than 15 cm deep in the clamp can reduce the amount of oxygen trapped in the crop. This action will minimise the level of yeast and mould growth, and ultimately the risk of mycotoxin contamination during storage. It is very important to seal the clamp properly, at the sides, on the top and the ramp.

Lauren Dimmack, Alltech animal health specialist, concurred with Davies. “After opening, you want to make sure the clamp face remains solid, and if you can push your fingers in, it is not packed densely enough,” she advised. Alltech is an international natural nutrition and scientific innovation company.

If farmers have had problems with storage mycotoxins in the past, Alltech can undertake free on-farm risk assessments as part of the Alltech Mycotoxin Management programme. These assessments can help to identify any weakness in the feed process.

“Mycotoxins are responsible for numerous undiagnosed health issues in European dairy and beef cattle, even when growing and harvesting conditions are reasonable,” Dimmack said. “The symptoms will be many and varied, but the outcome in all cases will be reduced animal performance and lost profits. It is now more important than ever to implement a mycotoxin control programme to ensure the health of your animals, the quality of their feed and the security of our food supply.”


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What is silage and how is it made?
Silage is fermented, high-moisture stored fodder which can be fed to ruminants or used as a biofuel feedstock for anaerobic digesters. It is fermented and stored in a process called ensilage, ensiling or silaging, and is usually made from grass crops, including maize, sorghum or other cereals, using the entire green plant (not just the grain).
Silage is made either by placing cut green vegetation in a silo, by piling it in a large heap covered with plastic sheeting, or by wrapping large bales in plastic film.
The crops suitable for ensilage are the ordinary grasses, clovers, alfalfa, vetches, oats, rye and maize; various weeds may also be stored in silos, notably spurrey such as Spergula arvensis. Silage must be made from plant material with a suitable moisture content, about 50% to 60% depending on the means of storage, the degree of compression, and the amount of water that will be lost in storage, but not exceeding 75%. Weather during harvest need not be as fair and wet as when harvesting for drying. For corn, harvest begins when the whole-plant moisture is at a suitable level, ideally a few days before it is ripe. For pasture-type crops, the grass is mowed and allowed to wilt for a day or so until the moisture content drops to a suitable level. Ideally the crop is mowed when in full flower, and deposited in the silo on the day of its cutting.
After harvesting, crops are shredded to pieces about 1.3 cm long. The material is spread in uniform layers over the floor of the silo, and closely packed. When the silo is filled or the stack built, a layer of straw or some other dry porous substance may be spread over the surface. In the silo the pressure of the material, when chaffed, excludes air from all but the top layer; in the case of the stack extra pressure is applied by weights in order to prevent excessive heating. (Source: Wikipedia)