Q. I have silage that tested high in butyric acid. Can I still feed it?
A. When ensiling grasses and legumes with moisture levels greater than 70 percent, it can be common to have butyric fermentation. This occurs when butyric acid is produced by anaerobic bacteria called Clostridia, which are present on the crop at harvest. Generally, lactic acid bacteria (LAB) produce sufficient acid and lower pH quickly enough to keep clostridia from growing. However, a quick pH drop is more difficult to achieve when forage is wet.
Butyric fermentation results in silage with lower dry matter (DM) and energy content. Clostridia also degrade the forage proteins, producing ammonia and biogenic amines, which can lead to lowered intake and metabolic/reproductive issues. These silages also have a higher pH and a rotten smell, coupled with the classic butyric (fecal) aroma.
You can still feed out this silage safely keeping a few points in mind:
- Obtain a laboratory analysis to accurately determine the level of butyric acid present.
- Start feeding out as soon as active fermentation is complete, usually after two weeks.
- Do not feed to pre- and post-fresh cows.
- Do not feed more than 50 grams of butyric acid per head per day. For example, if your laboratory analysis determined there is 1.46% butyric acid present, limit feeding to 7.5 lbs. per head per day on a DM basis.
Before feeding, you can spread out the silage and allow some of the butyric acid to volatilize without risk of spoilage. This may improve intake. Be aware that feeding butyric acid silage can increase the risk for ketosis in cows.
In the future, ensile forage at the right moisture levels to prevent losing DM and energy to butyric acid fermentation. Then, use a proven silage inoculant, with fast, efficient lactic bacteria and enzymes to generate sugars to fuel their growth, to help provide a faster fermentation.
I hope this information helps.
The Silage Dr.