A Discussion of SilagePro and Fermentation Prepared for: Consulting Nutritionist

American Farm Products – 30 years of experience in fermenting feeds faster and cooler.

American Farm Products was founded in 1982 by William Absalom. The company initially focused on improving protein retention in alfalfa silage by using selected enzymes to accelerate pH drop which facilitated a cooler fermentation. The result was less bound protein because of less heating. It turned out that the process was having a profound effect on the fiber components of silage and this effect was not limited to alfalfa. Since the 1980’s, improvements and research trials have been conducted in the United States, Canada, and Europe. In 1987, American Farm Products was listed by Inc. Magazine as number 100 of America’s 500 fastest growing companies during the five years between 1982 and 1987.

SilagePro is an unique product

SilagePro was first formulated as an enzyme product to produce an environment where forages would ferment faster and cooler utilizing natural bacteria. Somewhat variable results indicated that natural bacteria alone are not sufficient to provide consistent results. Consequently, four strains of lactic acid producing bacteria were added to the enzyme mixture to provide robust lactic acid production matched to the resulting enzyme activity. Taken separately, the bacterial portion of SilagePro is the cascade recommended by Weinberg and Muck (1996) to provide the most rapid pH drop. In their paper, Weinberg and Muck do a nice job of presenting the cascade growth pattern resulting from rapidly growing Enterococcus, which tolerates high pH, followed by Pediococcus, which grow at mid-range pH (5.5-4.5), and finally L. Plantarum, which are slower growing and prefer low pH (< 4.5).


It is important to control the entire fermentation process. For example, the following sample of haylage was treated with a product that contains only Enterococcus and L. plantarum. The pH did not pass through the middle pH range (5.0-5.5). Presumably, this was the consequence of no Pediococcus to drive this phase of the cascade and insufficient simple sugars to feed the bacteria due to the lack of enzyme activity. The result is a high level of butyric acid (almost 6%).



pH is the most import measure of fermentation

Fermentation is often measured in terms of different volatile fatty acids; however, it is pH that determines the overall preservation quality. Spoilage bacteria, such as clostridia, and other native heterolactic bacteria generally do not grow in low pH. It is true that lactic acid is the primary controller of pH in forage.

  • The two important factors concerning final pH are speed and the magnitude of the drop. The terminal pH of corn silage should between 3.6 and 3.8 with the pH dropping below 4 by day 4. To get the pH to a terminal level in 4 days requires viable bacteria that grow along the pH curve, sufficient simple sugars for the bacteria to utilize, good packing to eliminate the aerobic environment, and good covering (with more forage or plastic) to maintain the anaerobic environment. The following fermentation profile represents properly fermented corn silage (treated with SilagePro) that has been ensiled less than 1 month. At a pH of 3.5 (or for that matter, anything less than 3.8), spoilage bacteria will be greatly inhibited.



Below is another fermentation profile for a corn silage starter pile (treated with SilagePro) that was sampled at 14 days. Similar results were seen at 7 days with NIR profile. This corn silage was stable and being fed with no ill effects.


The ability to inhibit molds and yeasts is pH dependent.

It is well known that acetic acid at low pH inhibits molds and yeasts. At low pH, acetic acid has a hydrogen molecule attached to it (because it is a weak acid). With this hydrogen, the acetic acid is able to cross the membrane barrier of molds and yeasts where it releases the hydrogen. This is fatal to the organism since the intracellular fluid become acidic.

  • The pKa of acetic acid is 4.79 which is the pH when 50% of the acetic acid is hydrogenated. The lower the pH, the more myotic protection provided by acetic acid.