If the fermentation process doesn’t go just right, clostridia spores commonly found on forages can lead to the formation of excess butyric acid in ensiled forages. Ensiled alfalfa is especially vulnerable to butyric acid formation.
In order to combat this problem in alfalfa, Richard Muck, of the U.S. Dairy Forage Research Center, suggests the following steps:
Do not spread manure on alfalfa fields that already show regrowth.
Alfalfa should be ensiled at 30 percent dry matter with a pH of 4.7 (or 40 percent dry matter if using wrapped bales).
If alfalfa is rained on or cool, cloudy weather persists during the wilting stage, it will have increased risk for butyric acid formation. Start feeding it as soon as active fermentation is complete — about two to three weeks.