Gilad Ashbell

Technology of Forage and By-Products Preservation

17. Silage additives

Controlling the fermentation process in silage is more complicated than in other fermentation industries, and its scope is more limited. Silage fermentation is mostly uncontrolled, but improved understanding of the chemical and the microbiological processes involved in fermentation will give us more possibilities to control it. For many years farmers tried to raise the value of silage or to improve the fermentation process by adding various materials, mainly nutrients, but their efforts did not always lead to success. Nowadays, however, additives are becoming ever more popular in the silage industry. The use of additives is justified only when ensiling is done according to the best technological practice that we know and can apply; they can improve good silage, but cannot remedy the effects of bad management. Silage additives must be proved to provide better quality of silage, with reduced losses, positive effects on the cow, and increased profits. These benefits must be clear in each specific farm where the additives are used, and under the conditions that prevail there.

 

1. Inhibitors

Inhibitors serve mainly to suppress undesirable processes such as aerobic activities of bacteria, molds and yeasts, and to eliminate the activities of enzymes and clostridia. These aims are achieved mainly with chemicals, which are added in small amounts during the chopping. Inhibiting additives were discussed in the chapter on enrichment, above. The list of chemical additives is long, and it can also include several organic acids such as acetic, caproic, formic and benzoic, and mineral acids such as hydrochloric and sulfuric. Other chemicals that have been used include sodium nitrate, sulfur dioxide, formaldehyde, and paraformaldehyde.

 

2. Stimulators

Stimulators are used mainly to improve the effectiveness of the fermentation. These additives are generally bacteria (inoculants) and enzymes, which were also discussed above, under enrichment. The carrier substances for the bacteria or enzymes are usually molasses, sucrose, dextrose, whey, cereal grains, and various kind of pulp.

 

3. Substrate sources

These are usually applied in large amounts, and are added to the silage during the filling of the silo. Mixing is relatively easy because of the large amount that is added. These substrates, which do not need to be dry, may also be residues from the human food industry, such as peels, husks, molasses, whey, pulp or even additional ground grains. It is important to ensure that the source of substrate is correctly matched to the forage, in order to achieve a better forage fermentation formula with higher nutritive value. The addition of grains (of any kind) enhances the DM and energy contents of the silage, but it is recommended to grind the grain, so that the starch it contains can absorb moisture and thus improve the digestibility. Ground grains can serve as a good additive to wet and/or low-energy forage. The addition of by-products to silage, thus recycling them for animal feeding, yields important benefits in reducing environmental problems, and is a good solution to the problem of disposal of such residues.

 

 

 

 

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