Acetic Acid

The acid that is present in vinegar. It has a strong ability to prevent growth of yeasts and so should ideally be present in silages at a reasonable level to prevent heating and spoilage. It can be produced in silage in a number of ways, mainly by lactic acid bacteria. Acetic acid can be an indicator of a slow, inefficient fermentation driven by heterofermentative lactic acid bacteria. This type of fermentation can result in the production of other products in the silage that can depress intakes and means that energy has been wasted (see "Homofermenters and Heterofermenters" below). However, acetic acid can also be produced efficiently by homofermentative bacteria, from five-carbon sugars (e.g. xylose) and by the anaerobic conversion of lactic acid to acetic acid by Lactobacillus buchneri. In these situations the fermentation is efficient and the potential intake depressing compounds are not produced.