Heating is a natural result of the fermentation process that occurs during ensiling. However, sometimes this process can become unstable, with significant heating. When this occurs, valuable dry matter (DM) and nutrients — as well as milk production — can be lost.
Aerobic instability in silage is likely a result of spoilage yeasts, which can cause increases in forage pH. In turn, this allows for further spoilage by molds and undesirable bacteria. Where you can see spoilage, there have already been significant DM losses and increases in temperature.
Each 15°F increase in temperature on 1 ton of 30%-DM silage requires over 12.6 Mcal of energy. This ends up costing producers around 20 lbs. in lost milk production per ton of silage, in terms of energy equivalency. Plus, feed costs increase due to lost DM and more feed refusals.
Heating can occur at the following times:
- During filling and shortly after silage is enclosed. This is when micro-organisms begin to grow and produce heat naturally due to exothermic (heat-generating) biochemical processes. Plant respiration also produces heat. When the oxygen within the silage is consumed, the rate of temperature increase slows. The final temperature depends on oxygen availability and the types of micro-organisms that dominate in the crop.
- After silage is opened. Exposure to oxygen reactivates aerobic growth, which produces heat. The intensity and speed of this heating depends on the level of yeasts and molds present, speed of feed-out and environmental conditions.
To help prevent silage heating and resulting DM losses, use a research-proven forage inoculant that will drive an efficient ensiling fermentation at the start. Additionally, inoculants that contain Lactobacillus buchneri NCIMB 40788 at an effective dose can help address stability challenges. In fact, the high-dose-rate L. buchneri 40788 is the only active microbial reviewed by the FDA and allowed to claim efficacy in preventing the growth of yeasts and molds in silages and high moisture corn (HMC).
Producers also need to be at the top of their silage management game. Pack and fill silos and bunkers correctly to drive out excess oxygen, and seal silage structures as soon as possible after filling. All exposed surfaces need to be covered and sealed completely and effectively. Finally, correctly feed-out silage, use good face and feed management, and be sure the ration is properly balanced around the silage.
Well-managed silage that has been treated with a proven inoculant will minimize nutrient and DM losses, maximize quality, increase stable feed available and improve production from your forage base.
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