December 14, 2017

Most probiotic strains used in the poultry industry belong to one of two groups: spore-forming Bacillus species, or lactic acid bacteria (LAB). LAB, which comprise a variety of genera including Lactobacillus, Pediococcus, and Lactococcus, are characterized by their ability to thrive in acidic environments, such as the poultry gastrointestinal track, making them suitable candidates for use as probiotics. But unlike Bacillus species, very few LAB are able to form spores, which means that they require specific storage conditions to optimize their survival and viability. Loss of viability of the probiotic organisms will translate to a loss in effectiveness of the product in the field.

One apparent source of extreme confusion to consumers is which probiotic is administered where and why. Probiotics administered in the feed are not administered as living organisms but rather as spores. Why? Because in today’s modern feed mills the process of making the pellets and crumbles that we feed to birds require the addition of heat in one form or another. Heating is the same process that is used to sterilize surgical instruments so it stands to reason that heating would damage living organisms. Bacterial spores are better equipped to withstand the temperatures experienced in a feed mill so, to accomplish our goal when administering probiotics in the feed, we are actually administering spores of Bacillus spp. usually B. subtilis or B. licheniformis. When these spores are ingested, they must undergo transformation to vegetative species
before they start their metabolic processes. It is byproducts of these metabolic processes that are believed to be the active metabolites that work
in the intestine. While the roles are not clearly defined, many Bacillus spp. produce a variety of antimicrobial metabolites (e.g. bacteriocins) that, at high enough concentrations, are believed to act on the intestinal microbiome. As you might imagine the transition to vegetative state and building of sufficient levels of active metabolites is a long term and slow process. Therefore, Bacillus spores are probably best administered in the feed and administered for the life of the animal.

The LABs, on the other hand, are administered as fully functional vegetative organisms and are ready to start metabolism as they are ingested. Their metabolically active by-products are organic acids such as butyric, proprionic, and acetic acid. As they transverse the intestine these metabolites create a gradient of increasing acidity (decreasing pH) making a more inhospitable environment for the nasty gram-positive bacteria such as Clostridium and Salmonella. Because these are living organisms it is reasonable to believe that they will be killed or severely damaged by the feed manufacturing process and, as a result, these are best administered via the drinking water as water soluble products.

As with many of the alternative products on the market today, it is in the consumer’s best interest to understand and be able to read and interpret the label. Gone are the days when we could pick up a bottle of
penicillin and read that it contains 100 mg of procaine penicillin G per ml. and know that is what is in the bottle. The labels for the LABs are particularly confusing. One needs to know that you want to be using a product that contains living organisms and, as such, the label should clearly state how many organisms of what species are contained per gram of product. Many manufacturers incorrectly lead consumers to believe that they are using living organisms by making ingredient statements such as “dried Bacillus subtilis fermentation products”. These are not living bugs but rather by-products of some manufacturing process. If the product contains live bugs it will say so!!

One other source of great confusion is proper care and storage of live bugs. While these bugs are not extremely fragile, they do require a certain amount of diligence on the part of the consumer to maintain their viability and insure that live bugs are being administered to the animals.

Generally, with live microbial products, the colder the storage temperature, the longer the cells will remain viable. This is because lower temperatures reduce the metabolic activity of the live bacteria, which allow the cells to persist in a semi-dormant state. However, it is very important that the organisms experience the fewest amount of freeze-thaw cycles as possible. In other words, if a microbial product is received frozen, it should be kept frozen until use; if a microbial product is received unfrozen or allowed to thaw, it should be kept at -4 degrees Celsius until use and never be frozen. Storage conditions at or above room temperature should be avoided for storing LAB for more than a few days.

Equally as important as temperature is humidity. In order to maintain the highest viability of LAB-based products, humidity should be minimized during storage. Hydration of LAB during storage will cause the bacteria to become metabolically active - the cells will ‘wake up’, but will soon die after quickly exhausting all of the available energy. Like most probiotics, LAB products are meant to be activated either shortly before, or within their intended environment (i.e. the gastrointestinal tract if a bird), and should remain in a dry, sealed container until that point.

In summary, non-spore-forming bacteria, such as LAB, are highly sensitive to temperature and humidity conditions, and these variables should be taken into account when shipping, storing, and applying LAB-based probiotics. Knowing what products to use and how to use them will help consumers significantly improve their success with probiotic administration.

For More Information:


Evan Hutchinson, Arm and Hammer Animal Nutrition
Robert L. Owen, VMD, Ph.D., Best Veterinary Solutions

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