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“Did you know?” : silage aromas & meanings

“Did you know?” : silage aromas & meanings

The aroma of the silage can help to identify what has occurred during the fermentation , and is an important tool in making a preliminary assessment of its quality.

Do the test! Grab silage and identify which smell it is close to. See below and download PDF for more info.


Preserved forages have different aromas depending on how well they have been preserved. The most desirable acid for forage preservation is lactic acid. Lactic acid has NO AROMA.


Aroma Cause  Origin Efficiency
Sharp Acid This smell is synonymous of a lactic fermentation. It leads to good silage intake and milk production. This kind of silage could suffer from heating. This is why good face management is required. Homolactic fermentation 100%
Tobacco It is the consequence of high level of heating. Likely pH remains high with low energy content though intake can remain high. High ensiled air/low compaction facilitating yeast and acetobacter development. 49%
Alcohol Growth of yeast during ensiling and storage (poor compaction and ongoing air entry). Yeast 49%
Butyric Clostridia growth can have many explanation: it could be due to limited sugar, soil contamination, excess buffering, excessive compaction of wet silage or high ensiling temperature killing Lactic acid bacterias. Clostridia

Acetyl alcohol

Alcohol smell is also associated with enterobacteria when converting glucose to acetoin. Lactic acid bacteria can also produce Acetate/alcohol/diacetyl when glucose is silage is limited. Heterofermentative LAB


Variable depending on reason
Fizzy to taste

Red / orange

Typical of silage gas production as the pH falls during ensiling (NO2). As gas attempts to escape, it is adsorbed into the silage moisture. High residual nitrogen in plant (can make corn yellow colored) Variable depending on nitrate level
Acetic Acid Typical smell of heterolactic fermentation such as Lactobacillus Buchneri or Lactobacillus Brevis. If this smell is associated with heating silage, then it is due to acetobacter activity. Heterofermentative LAB or
Variable depending on reason