When air comes in contact with the silage, aerobic microbial activity will commence and the result to the producer is dry matter and nutrient loss. Heat is often produced but may not significantly increase the temperature in corn silage as the wet silage mass acts as a heat sink. One should not assume, however, that corn silages are exempt from deterioration when exposed to air. The microbial activity associated with silage deterioration of corn silage has been studied extensively and most researchers believe yeasts to be the primary organisms involved. Some aerobic bacteria, especially those capable of metabolizing lactic acid, likely have a interactive role with the yeasts in the spoilage process.
Molds also play secondary roles during deterioration.
If toxin production accompanies their growth, it can cause severe problems for dairy cows including off-feed, reduced immune response and delayed breeding. It is difficult to predict if a fermented forage will be stable or prone to extensive deterioration. A great amount of research has been conducted to attempt to correlate aerobic deterioration with a chemical component in forages or to identify natural chemical constituents that promote stability. These studies have shown only butyric acid to be detrimental to aerobic deterioration. It is ironic that the silage we consider poor from a nutritive and palatability perspective, happens to confer stable bunklife to corn silage.