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Simplifying silage inoculant bacteria

Jim Mattox Published on 06 February 2015

No one really knows the origin of the term “jack of all trades.” But I am convinced that the term must have been coined to describe a farmer. Farmers, by far, have the broadest knowledge base, dabbling in almost every science from architecture to zoology.

This is why I am surprised at the aversion displayed by farmers across the country when it comes to evaluation of different strains of fermentation bacteria.

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You can talk to a farmer for hours about genomics or the complicated science of milk extraction and get a passionate and educated response. However, just mention the word Lactobacillus plantarum (or L. plantarum), and the lights in their eyes go out, their feet start shifting, watches get looked at, and all the undone chores are suddenly remembered.

I can only take a guess as to the cause of this aversion, but I think it relates to the long history of misrepresentation by both reputable and not-so-reputable companies.

The silage-additive industry has zero regulations. Companies can make any claim they want without fear of repercussion. “Fly-by-night” silage inoculant salesmen abound more than any other industry, spreading their misinformation and thriving off gibberish.

It’s a sad situation because countless university studies conclusively prove that silage inoculants are a good investment and crucial to the farm’s bottom line.

However, the silage inoculants industry is rapidly changing. Regulations will increase, and companies will be forced to pay millions to have their bacteria strains registered. The abilities of some of the newer bacteria strains are very intriguing, and new technologies are being developed every year.

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Farmers that want to gain an edge must be prudent and stay updated. Let’s look at the mode of action behind some known bacteria strains currently being marketed and help decipher fact from fiction when evaluating silage inoculant bacteria.

Lactobacillus plantarum

Bacteria are living organisms just like cattle, but we use their scientific name rather than their common name. We don’t walk around saying Bos Taurus to describe our cows, but with bacteria we always use the scientific name.

This methodology is intimidating to some, but it’s important to know the differences. You wouldn’t run a very profitable feedlot if you were finishing Jerseys, and likewise a dairy milking Angus would likely struggle to fill the milk tank.

L. plantarum is the most commonly used fermentation bacteria and is present everywhere in the environment. If you look closely enough, you will find some on your skin right now. L. plantarum is used in a wide array of fermentation processes such as making cheese, pickles and soy sauce.

In silage, L. plantarum is used to rapidly reduce pH and preserve feed faster. In general, the more L. plantarum present during fermentation, the faster the feed is preserved.

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Richard Dietz of Dietz Consulting LLC advises that silage inoculants should be carefully selected and contain high levels of L lactic acid-producing (rumen-friendly) organisms. Many strains of lactic acid-producing bacteria produce d-lactic acid, which can be detrimental in the rumen.

Pedicoccus acidilacti

Another commonly used bacteria that is often used in conjunction with L. plantarum is Pediococcus acidilacti. Chopped corn is around 6.5 pH when it is first harvested, and it is a race against time to reduce that pH to below 4.5 (the lower, the better).

L. plantarum does not work well in a high-pH environment (more than 5.5), so this is where the starter culture P. acidilacti is utilized. Similar to running a relay race, the P. acidilacti lowers the pH from 6.5 down to 5.5 and then passes the baton off to L. plantarum to finish the race.

Products that only have one strain of bacteria (usually L. plantarum) are relying on natural fermentation to lower the pH down to the point where the L. plantarum kicks in. This is like running the 4x100 relay with Grandma running the first leg of the race.

Enterococcus faecium

During the initial phase of fermentation it is imperative to reduce the pH and create an environment that inhibits undesirable contaminant growth. To achieve this effect, the use of a very fast fermentation organism is critical. Certain strains of Enterococcus faecium are capable of producing these results.

These strains have been researched and selected for their ability to produce high levels of l-lactic acid in an oxygen-rich environment with a pH of 6.5.

The extremely fast growth of these strains of E. faecium (doubling in numbers every 16 to 18 minutes) is capable of producing very high levels of l-lactic acid, thus reducing pH, creating an anaerobic (oxygen-free) environment and inhibiting the growth of undesirable micro-organisms. Speed is critical in stabilizing silage, and E. faecium plays a pivotal role in fast fermentation and nutrient retention.

Lactobacillus buchneri

Perhaps the most famous bacteria on the market today is Lactobacillus buchneri. L. buchneri is a well-researched product that enhances aerobic stability, meaning it keeps silage stable in the presence of oxygen. Many farmers use L. buchneri to keep their silage cool during feeding, especially in the hot summer months. L. buchneri produces high levels of acetic acid (vinegar) that inhibits yeast.

Secondary heating is a major problem, and yeast is the primary cause. L. buchneri does a very good job at keeping silage cool during feedout, but this organism also has some major drawbacks. L. buchneri is a very slow fermenter, so the dry matter losses are much more substantial with this organism than with lactic acid-producing organisms.

There is also an impact on cattle feed intakes. Cows prefer sweet-smelling lactic acid over the nose-burning vinegar smell you get from acetic acid.

Furthermore, the latest research from the USDA Forage Research Center shows a 3.5 percent animal performance increase with lactic acid-producing (homolactic) silage inoculants. The same results were not observed with the heterolactic (acetic acid-producing) strains such as L. buchneri.

The bottom line is that situations exist where farms need to use L. buchneri, but they must consider that in doing so they are giving up 3 to 5 percent more dry matter loss along with 3 to 5 percent animal performance. These factors must be considered when doing the cost/benefit analysis of using Lactobacillus buchneri.

Lactococcus lactis

Clostridial fermentation produces butyric acid. Butyric acid is one of the nastiest substances on the earth and makes my stomach turn as I type the words. Not only does butyric acid stink to high heaven, but it triggers ketosis, HBS and wreaks havoc on milk production and components.

Butyric acid can put you out of business quicker than just about any other issue on the farm and should be avoided at all costs.

Butyrate is not often a problem in corn silage but can occur if the silage is too wet or irrigated by manure water over the top of the plant. Usually, butyric acid is observed in alfalfa haylage, grass silage and just about any silage crop other than corn.

Lactococcus lactis is a fermentation bacteria that is used in cheese culture to inhibit clostridia and listeria. If clostridia can be controlled, then butyric acid can be reduced or eliminated. Silage inoculants that contain L. lactis should be used when the farm has a problem with clostridial fermentation.

Conclusions

  • Lactic acid-producing bacteria are utilized in multiple strain configurations where each strain plays a specific role during the fermentation process.
  • Every company has different claims but most important is speed of fermentation.
  • Silage inoculant salespeople should be able to tell you where their product is manufactured and provide peer-reviewed research to support their claims.
  • Rapid changes in biotechnology are bringing better fermentation bacteria to the market. These new bacteria could have major benefits for your farm, but it’s a “buyer beware” market.
  • Do your homework and critically evaluate the claims before investing. Silage inoculants when combined with good management practices can help keep more nutrients, reduce yeasts and molds, and control secondary heating. PD

PHOTO
More farmers understand kernel-processing scores than silage inoculant bacteria, which is an unregulated industry. Understanding bacteria modes of action can help producers determine what inoculants to use. Photo by Lynn Jaynes.

jim mattox

Jim Mattox
Feedtech Solution Manager
DeLaval Inc.

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