Fermentation
Silage undergoes anaerobic fermentation, which starts about 48 hours after the silo is filled, and converts sugars to acids. Fermentation is essentially complete after about two weeks.
Before anaerobic fermentation starts, there is an aerobic phase in which the trapped oxygen is consumed. The closeness with which the fodder is packed, determines the nature of the resulting silage by regulating the chemical reactions that occur in the stack. When closely packed, the supply of oxygen is limited; and the attendant acid fermentation brings about the decomposition of the carbohydrates present into acetic, butyric and lactic acids. This product is named sour silage. If, on the other hand, the fodder is unchaffed and loosely packed, or the silo is built gradually, oxidation proceeds more rapidly and the temperature rises; if the mass is compressed when the temperature is 140 to 160 Fahrenheit, the action ceases and sweet silage results. The nitrogenous ingredients of the fodder also suffer change: in making sour silage as much as one-third of the albuminoids may be converted into amino and ammonium compounds; while in making sweet silage a smaller proportion is changed, but they become less digestible. In extreme cases, sour silage acquires an unpleasant odour although it keeps better than sweet silage when removed from the silo.
In the past, the fermentation was conducted by indigenous microorganisms, but, today, some bulk silage is inoculated with specific microorganisms to speed fermentation or improve the resulting silage. Silage inoculants contain one or more strains of lactic acid bacteria, and the most common is Lactobacillus plantarum. Other bacteria used in inoculants include Lactobacillus buchneri, Enterococcus faecium and Pediococcus species.
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Famous quotes containing the word fermentation:
“Unquiet souls!
MIn the dark fermentation of earth,
In the never idle workshop of nature,
In the eternal movement,
Ye shall find yourselves again.”
—Matthew Arnold (1822–1888)
“Two principles, according to the Settembrinian cosmogony, were in perpetual conflict for possession of the world: force and justice, tyranny and freedom, superstition and knowledge; the law of permanence and the law of change, of ceaseless fermentation issuing in progress. One might call the first the Asiatic, the second the European principle.”
—Thomas Mann (1875–1955)
“A tree is made to live in peace in the color of day and in friendship with the sun, the wind and the rain. Its roots plunge in the fat fermentation of the soil, sucking in its elemental humors, its fortifying juices. Trees always seem lost in a great tranquil dream. The dark rising sap makes them groan in the warm afternoons. A tree is a living being that knows the course of the clouds and presses the storms because it is full of birds’ nests.”
—Jacques Roumain (1907–1945)