Silage Loss: Causes & Consequences
If beef producers lose 20% or more of their herd, how upset would they be? How about a corn farmer that lost 20% of a standing cornfield to pests or some other natural disaster? In both cases, it would be fair to say that there would be many questions about why those losses occurred, and how to prevent them in the future.
Yet similar losses occur every year in silage bunkers and piles across the U.S. Losses of 15% of more of the harvested dry matter commonly occur, representing significant financial costs. Storage losses also affect the feeding value of the remaining silage. Feeding even low levels of spoiled silage results in reduced intake, lowered digestibility, and poor cattle performance.
The root cause of these issues is the failure to keep oxygen out of the silage. When it comes to silage fermentation, the “good” bacteria require anaerobic conditions. These microbes produce lactic acid resulting in a rapid drop in pH and maximum dry matter preservation. If oxygen is present, undesirable microbes such as yeast and molds feed on the most digestible nutrients reducing the amount of recoverable dry matter and the energy content of the silage.
Management Tips: Maximizing Value & Minimizing Loss
Harvesting at the right moisture content is the first step in maximizing silage value. Harvest should start at no wetter than 70% moisture with the goal of being completed before the crop is drier than 58 to 60% moisture. The length of cut should be between ½ to ¾”. Dull knives tend to tear rather than cut cleanly making it more difficult to pack.
Using inoculants can help increase the amount of desirable bacteria resulting in a faster pH drop and increased dry matter recovery. Inoculants can also improve aerobic stability when the silage is fed. Remember that inoculant strains are living organisms, so avoid exposing them to excessively high temperatures.
Packing the pile well can be challenging, especially with modern, high-capacity chopping equipment, but is an essential step to exclude oxygen. Adding additional packing tractors may be necessary for sufficient capacity. Keep the layers uniform and less than 6” in depth. Packing needs to be continuous throughout the filling process.
Covering a silage pile is arguably the least desirable job on a farm, but vitally important to preserve feed value. An uncovered pile can lose 60% of the dry matter in the original top three feet. An oxygen-barrier film combined with a white-on-black plastic cover results in less loss compared to a layer of plastic alone. Cover the pile as soon as possible after harvest is completed. Waiting as long as 12-24 hours after harvest significantly increases storage losses.
Finally, keep safety in mind. Slopes should be no steeper than 1 to 3 (one foot of rise for three feet of horizontal) to reduce the chances of rollover. Keep the height of the pile no more than the unloading equipment can reach to reduce the risk of catastrophic, even life-threatening avalanches.
Source: Warren Rusche, South Dakota State University
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