Aerobic Instability

Silage that heats on exposure to oxygen suffers from aerobic instability. In research trials the length of time a silage is stable is measured by the time it takes to heat by a specific amount, most commonly 2ºC. As previously mentioned (see "Yeasts and Molds" above) most of the heating events seen in silage result from the growth of yeasts. When determining in the field if a silage is heating, it is important to note and record the ambient temperature on the day the silage was made. It is normal for a silage to increase in temperature by 15 - 20ºF during a good ensiling process. So, if the forage was harvested on days when the temperature averaged 80ºF it would not be abnormal for the silage to be 95-100ºF. However, if the same silage is 120ºF, then it is heating. Just because the silage "steams" as it is removed during feedout in winter does not necessarily mean that it is heating!