Silage fermentation and additives

Abstract

The main objective of making silage is to maximize the conservation of original nutrients in the forage crop for food at a later date. The final quality of the silage can only be as good as the quality of the initial crop placed in the silo. The process of making a good silage includes 1) quickly removing air from the forage mass in the silo, 2) rapid production of lactic acid for rapid pH reduction, and 3) continuous exclusion of silage air during storage. The rapid removal of air prevents the growth of unwanted aerobic bacteria that can compete with the beneficial lactic acid bacteria (LAB). During active fermentation, LAB uses water-soluble carbohydrates to produce lactic acid, which is mainly responsible for increasing the acidity and decreasing the pH in the silage. In addition, it inhibits the growth of undesirable anaerobic microorganisms, such as enterobacteria and clostridia, which tend to be intolerant at a low pH. When the fermentation of the silage is completed and if it is kept away from the air, the silage remains fairly stable for long periods of time (years). Aerobic stability is a term used to define the period of time during which the silage remains stable and does not spoil after being exposed to air. Because air feeds yeast growth, minimizing their numbers and minimizing air exposure in silage is an important goal. Various organic acids have been used, including potassium sorbate, sodium benzoate and propionic, which inhibit yeasts to improve the aerobic stability of silages. The application of microbial inoculants and chemical additives to the forage is highly recommended to maximize the time that microorganisms have in contact with fermentable substrates. Bad fermentations and aerobic stability will cause the loss of nutrients, low animal productivity and farm profits. Recommended management practices should be followed for the harvesting, the filling of silos, the use of appropriate additives and silos coverings.