The goal of an inoculant is to help ensure your crop is preserved as closely to harvest as possible – this means the production of lactic acid and a rapid drop in pH to then actually halt fermentation. The goal to preservation is to quickly reach a terminal pH; fermentation halts when either the bacteria run out of substrate to ferment or reach a terminal pH. The more rapidly this occurs the less dry matter is lost. 

So why is there so much difference in inoculant pricing? There are very few regulations in the area of inoculants, which is a major reason there are so many products. How can you evaluate what you are purchasing and evaluate the cost-benefit ratio? Here is a short list of some of the reasons.

Factors impacting cost

1. Bacterial species that are included in the product: The number of different strains of bacteria can affect the cost. Different bacterial strains are more efficient at growing during fermentation. This would be called bacterial yield – the better the yield, the less expensive the cost of production. Sometimes, the bacteria a company adds to a product could have a lower yield, thus cost of production would be higher and affect the cost of the product. Reputable companies are most concerned about results, not just cost.

2. What is the difference in bacterial strains? First of all, bacteria are named by genus and species. This is probably the area of most confusion; while nearly all inoculant products will include a Lactobacillus plantarum bacteria, this does not mean all of these Lactobacillus plantarum bacterial strains are the same. How could they differ? The best example I can think of is the strain of E. coli 0157, which causes potentially fatal intestinal infection in humans. E. coli bacteria are found widely in nature, but not all are pathogenic. In this same way, different L. plantarum bacteria are not the same. L. plantarum is used in the food industry for fermentation, but, again, the strains are specifically developed. The major inoculant companies have specific strains of bacteria that are grown and developed just for them. Bottom line: Not all strains of bacteria are the same. 

3. What is the source of the strains that companies use? We have talked about the fact that many bacteria are used in industry for fermentation and their production of enzymes; this is also true of many yeast and fungal organisms. Because of this, there are many bacteria that can be purchased from companies that have already used the organism for another purpose. For example, L. plantarum is used in industrial applications in the starch, beverages, food and textile industries. These strains can be purchased by inoculant companies to be included in their product and are listed on the label as L. plantarum. Sourcing bacteria from industry certainly could influence the cost of the inoculant. If the bacteria are not always sourced and grown the same way, the results could vary. Again, the major companies grow their own strains of bacteria solely for use in their inoculant.

4. What strains are included? The strains that are included are for different reasons. First, Lactobacillus buchneri is included for its benefit in aerobic stability. The strains included typically are included to assist in fermentation across the range of fermentation pH. All organisms have “ideal” pH range in which they grow, as well as a preferred substrate (what they use for an energy source to grow on). The top companies use strains they have developed for the best results and that grow ideally at different pH levels. The inclusion of different strains has an impact on cost of the product. 

5. How many bacteria should be applied to the crop? This number depends on several things. The crop is one; the corn plant has more naturally occuring lactic acid bacteria than small grains or hay crops, so the number of bacteria applied could be a lower number. However, research by the University of Florida showed that just adding more bacteria to a product does not necessarily result in a better fermentation. The number of bacteria on the label is sometimes confusing. The number to compare is the number of colony-forming units (CFUs) applied per gram of silage. The CFUs do not tell you what percentage of the different bacteria are in the product, only the total number. Again, the top companies have research on the CFUs of their bacteria and have selected the best rate of application. Changing the percentage of the different bacteria could affect the cost, as they could have a larger amount of a less expensive bacteria, yet the total count is still comparable to reputable products. 

6. What research does the product have? The top inoculant companies have spent time and money performing research. Testing products on the dairy can be time-consuming and challenging. This is one reason to only consider reputable products that have already done research on their products. One other consideration to remember when evaluating product research is the research being shown was done on the product that is positioned to buy. Sometimes companies change their products – different bacterial counts, different bacteria, etc. – for example. If changes are made, then new research needs to be completed with the new product. Research really comes in a couple of different forms: university (third party) and field research. University research is typically the best form, and many times, it has been published in a journal where others reviewed the protocol. Field research can be of value provided it was well-run and well-controlled.  

Howard Jensen is a large herd specialist with American Farm Products. Email Howard Jensen.