SILAGE FERMENTATION AND SILAGE ADDITIVES - Review -

Advances in silage technology, including precision chop forage harvesters, improved silos, polyethylene sheeting, shear cutting silo unloaders, and the introduction of total mixed rations, have made silage the principal method of forage preservation. A better understanding of the biochemistry and microbiology of the four phases of the ensiling process has also led to the development of numerous silage additives. Although acids and acid salts still are used to ensile low-DM forages in wet climates, bacterial inoculants have become the most widely used silage additives in the past decade. Commercial inoculants can assure a rapid and efficient fermentation phase; however, in the future, these products also must contribute to other areas of silage management, including the inhibition of enterobacteria, clostridia, and yeasts and molds. Nonprotein nitrogen additives have the problems of handling, application, and reduced preservation efficiency, which have limited their wide spread use. Aerobic deterioration in the feedout phase continues to be a serious problem, especially in high-DM silages. The introduction of competitive strains of propionic acid-producing bacteria, which could assure aerobically stable silages, would improve most commercial additives. New technologies are needed that would allow the farmer to assess the chemical and microbial status of the silage crop on a given day and then use the appropriate additive(s).