The Organic Acids in Silage as Determined by Gas Chromatography

A method of extracting organic acids from silage and of separating them in the esterified form by gas chromatography is described. The method was applied to a study of the volatile fatty acids and of lactic and succinic acids in alfalfa silage. Fresh alfalfa contained small amounts of lactic, acetic and succinic acids. The quantities of these acids increased during fermentation of the silage but succinic and lactic acids decreased at later stages of fermentation, while butyric acid became prevalent. Wilting of the alfalfa crop for 8 hours prior to ensiling decreased the rate of formation of all acids and prevented the decrease of lactic and succinic acids. Butyric and propionic acids were present in only small quantities. A more severe wilting treatment decreased the rate of formation of acids still further. Some acids not detected by other methods were found in trace amounts.