Selecting Inoculants

When comparing different types and brands of silage inoculants, there are a number of important considerations that can help you determine the best product for your forage management system. These considerations include:

Product Data

Be sure there is ample data for the specific product in the target crop from trials conducted at independent research facilities, such as universities, verifying their claims. Are these data statistically analyzed and published in reputable journals and research meetings? These trials should validate efficacy of the product at the application rate it is being sold at and should validate any and all claims made for the product. Without data to validate specific product claims, buyer beware!

Read and Understand the Product Label (Figure 1)

Number of bacteria, application rate and weight:

  • Does data supplied by the company validate the recommended application rate?
  • Fermentation aids (it is generally accepted) should be applied at a minimum of 100,000 CFU/g forage
  • Spoilage inhibitor rates vary
  • Calculations may have to be done to determine the application rate of bacteria on forage (Figure 2).

Range Chart
Figure 2
Rate of Bacteria on Forage Formula

Figure 1
Typical Inoculant Label Info

In the U.S. for microbes to be legally included in products, they must be on the list of organisms approved by the American Association of Feed Control Officials (AAFCO).
See Table 1.

Suitability of Product Form

Dry granular application may be easier but is less effective than liquid application as crop dry matter increases (Figure 3). Granular Inoculants should not be used in crops with dry matter above 50% (less than 50% moisture).

Figure 3
Typical Inoculant Label Info

Table 1

Organisms Approved by AAFCO for Use
in Animal Feed Products in the US
Aspergillus niger
Aspergillus oryzae
Bacillus coagulans
Bacillus lentus
Bacillus licheniformis
Bacillus pumilus
Bacillus subtilis
Bacteroides amylophilus
Bacteroides capillosus
Bacteroides ruminocola
Bacteroides suis
Bifidobacterium adolescentis
Bifidobacterium animalis
Bifidobacterium bifidum
Bifidobacterium infantis
Biflidobacterium longum
Bifidobacterium thermophilum
Lactobacillus acidolphilus
Lactobacillus brevis
Lactobacillus buchneri
(cattle only)
Lactobacillus bulgaricus
Lactobacillus casei
Lactobacillus cellobiosus
Lactobacillus curvatus
Lactobacillus delbruekii
Lactobacillus farciminis
(swine only)
Lactobacillus fermentum
Lactobacillus helveticus
Lactobacillus lactis
Lactobacillus plantarum
Lactobacillus reuteri
Leuconostoc mesenteroides
Pediococcus acidilactici
Pediococcus cerevisiae (damnosus)
Pediococcus pentosaceus
Propionibacterium freudenreichii
Propionibacterium shermanii
Saccharomyces cerevisiae
*Enterococcus cremoris
*Enterococcus diacetylactis
*Enterococcus faecium
*Enterococcus intermedius
*Enterococcus lactis
*Enterococcus therniophilus
Yeast (as defined elsewhere)
*Formerly cataloged as Streptococcus.


Your Needs

Does the type of product match your expectations?
Do you need a fermentation aid or a spoilage inhibitor?
Is there independent data to show that the product can do what you are looking for?

Some products require pre-incubation to achieve the correct numbers for product efficacy: consider carefully whether you are prepared for, and capable of, taking on the burden of production and quality control required for this.


The three enemies of these live products are heat, moisture and air. Prevention from exposure to heat comes down to following storage instructions, but packaging must be designed to prevent exposure of the contents to moisture and air.

  • The use of high barrier foils is one common approach that achieves these goals, as is packaging in sealed tubs.
  • Manufacturers should also use nitrogen flushing during packaging to minimize residual oxygen and include specific preservation agents, e.g. moisture scavengers, in the product formulation.


Levels of enzymes: if the product claims to include enzymes, guaranteed levels should be declared and they should be the same as those used in trials to validate product efficacy.

Product Stability

The stability of the inoculant in the applicator tank or hopper is also important. The bacteria in liquid applied inoculants can die off quite quickly following rehydration unless the product contains a stability enhancer (Figure 4). Do not allow water with bacterial inoculants to reach temperatures above 95-100 F during use. Ask to see the rehydration stability data for any product you are considering. If liquid applied product becomes slimy, it should be discarded (bacteria have died, releasing their DNA and causing the sliminess). Granular, dry applied inoculants also die off in the hopper (Figure 5) as moisture is absorbed from the atmosphere and the temperature increases. The product flow characteristics may also suffer. Consider discarding granular inoculant left over in the hopper at the end of the day to ensure optimum product performance.


Calibrate your application rates for liquid and dry-applied inoculants. Application rates should be checked several times a day. Even distribution of the inoculants is also a key factor in their ability to help the fermentation process. Liquid flow rates for different spray nozzles are given in Appendix II. Products are best applied at the chopper box or accelerator on the harvester. The DE1000 (Dohrmann Industries) is a low volume liquid applicator (1.28 oz per ton) which has been validated as achieving even distribution. The product reservoir on this system is a 10 gallon insulated tank, which helps keep the product cool to maintain viability.

It is generally accepted that using a proven, validated inoculant as part of a good forage management program will give a return on the required financial investment. The guidelines above should help you in the selection process to ensure that the product you select is applied as a live, viable product ready for the ensiling challenges that lie ahead. However, inoculants are not “magic bullets” that will make up for lax management practices: they are one tool to help as part of the overall management program.

Figure 4 & 5

Figure 4 & 5


Recommended storage conditions should be read, understood and followed. The shelf life of the inoculant is linked to the recommended storage conditions: improperly storing the product could significantly reduce its shelf life and efficacy.


Always check for an expiration date and never use expired inoculant!

Additional Information:

Dr. Limin Kung, Jr. Article (PDF) PDF
Courtesy of Hoards Dairyman

Investigating Inoculants (PDF) PDF

Guidelines for Inoculant Mixing and Cleaning (PDF) PDF