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Silage uncovered: A guide to forage management

Derek Wawack, Alltech On-Farm Support forage specialist, explains the key things he looks for when inspecting a silage pile, and the steps farmers can take to avoid costly issues.


When I go on-farm for a bunker audit, the first thing I do is inspect the silage pile for any safety concerns. Large cracks, often found when there are two crops butted together, can come down, causing an avalanche or collapse. Are there overhangs? Tires falling down? Bales that could tip over? Always exercise extreme caution when around large piles.


Molds like PenicilliumAspergillus and Fusarium are often found in corn silage and are common mycotoxin producers.

Colorations can help us identify molds, especially in corn silage. White-to-red/pinkish molds are Fusarium, or field-borne, molds. Blue-green molds are typically Penicillium, which is more often storage-related but can occur in the field under certain weather conditions. Aspergillus, which is very common in dry climates, is olive green to yellow in color.

When I observe large mold lines, I do not touch, inhale, grab or sample those areas. Many molds cause health issues to both animals and humans, and they can also produce a fair number of different mycotoxins.

In humans and animals, Penicillium mold alone can cause dermal irritation as well as gut health complications if ingested. Mycotoxins can also cause performance and reproductive problems.


Increased surface area permits more oxygen to penetrate the feed, triggering mold and yeast growth, which increases heating. We look for a smooth face, with little loose material at the base and edges. The proper facing and feed out equipment can help reduce shrinkage. A shaver provides a very smooth and clean face and can help reduce losses with proper management. Rakes or claws will cause tine marks, increasing surface area, but they do limit oxygen penetration during facing. Finally, bucket facing leads to a lot of oxygen penetration due to lifting the pile face.

Temperature inspection

Along with evaluating facing techniques, we can utilise infrared cameras for hot spot detection on the piles. These cameras are used to look for areas of aerobic instability that could be due to yeast, mold, bacteria or even the management of facing practices. Shavers tend to not allow oxygen very deep into piles. Rakes and buckets can allow oxygen into the piles, resulting in quicker spoilage.

Other issues we see on infrared cameras are yeasts. Yeasts tend to show up as a large bubble on the images and, being water soluble, will drain down the pile. Yeast can contaminate the top and then drain down through the face. In contrast, molds have a tendency to grow in a linear or spherical fashion. This means molds will stay more toward the top of the pile and will develop in lines.

More basic temperature probes are also effective in diagnosing heat and fementation issues.


We also look at how well the plastic has been managed. Has it been pulled back too far? How many sheets are being used? Are the tires touching? Are the sides covered well and is the plastic pulled out with sand around the edges if it’s a drive-over pile? Or is it a bunker in which the plastic has been, at the very least, run down the walls and double overlaid?

Due to the curvature of the pile surface area, taking proper precautions and good management of the top of the pile can result in reducing up to a third of spoilage and oxygen penetration:

  • TiresYou don’t want to see large spaces between tires; in fact, the tires should nearly be touching. For ease of weight and placement, side walls work the best and reduce water-holding capacity, which can encourage bugs and pathogens.
  • Plastic:One black and white sheet with an oxygen barrier film, or two layers of black and white plastic, will protect the top of the forage from the elements and discourage animals from penetrating your feed.
  • CuttingDepending on height, conditions and other safety factors, try to keep the plastic cut 6 inches to 1 foot from the face edge. Two to three feet is common, but air, rain and other weather conditions can truly damage your forage when it is exposed to the elements.
  • TreatmentMost spoilage occurs at the top of the pile, where the packing density isn’t as high. A mold inhibitor can help counter the impact of increased oxygen flow in this area.

Up to 60 percent of the average farm’s expenses are feed-related. By increasing the quality of your forage and reducing shrinkage, considerable cost savings can be achieved without even leaving the farm.