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Proving the potential of probiotics in beef cattle

Caution is the word for now from an Alberta intestinal health research group on products claimed to have prebiotic or probiotic activity to promote health benefits for people and livestock.

Dr. Doug Inglis

Dr. Doug Inglis

Use of these products won’t harm cattle or people. The worst that could happen from a production standpoint is that they will increase costs with no benefit to the cattle, says Dr. Doug Inglis, a research scientist at Ag Canada’s Lethbridge Research Centre and adjunct professor with University of Calgary Veterinary Medicine.

He’s not nixing the potential merit of prebiotics and probiotics to provide health benefits. In fact, that’s the very question the research group is studying. It’s just that at this point in time there’s not enough scientific evidence to validate the general claims on most products, let alone make specific claims. That’s largely because our basic understanding of how probiotics and prebiotics impart health benefits is missing.

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General claims are usually vague and oftentimes misleading statements about supporting gastrointestinal health. Given that intestinal health has a systemic effect on overall health, some companies extend claims to boosting the immune system, relieving stress and depression, having anti-inflammatory properties, improving glucose tolerance and reducing upper-respiratory tract infections. Products for livestock may claim that they enhance the immune system, improve digestive health, maintain or improve intestinal integrity and barrier function, increase feed efficiency and promote growth.

What you want to see on a product are specific claims — what to expect and why — for instance, the reduction in the number of specific pathogens (salmonella, typhimurium and/or E. coli O157:H7) as a result of having to compete against probiotic bacteria, Inglis explains.

Other modes of action commonly believed but not fully supported by science include directly fighting off harmful bacteria, improving the barrier function of the intestinal wall to bar harmful bacteria, stimulating immune function, reducing inflammation, and producing a growth substance.

“Another concern is that almost all of the science on prebiotics and probiotics has been done in monogastrics so we are really uncertain if there is a health benefit to ruminants,” he adds. Researchers have only touched the tip of the iceberg when it comes to understanding the activity of prebiotics and probiotics in the complex, diverse ruminant digestive system.

Probiotics, often called veterinary biologics or direct-fed microbials in veterinary medicine, are live micro-organisms that work in the small and large intestines.

The most common bacterial probiotics in products for people and livestock today are a few species of lactobacillus and bifidobacterium. They are easy to grow and have been formulated to survive digestion in the stomach so that they reach the intestines, however, they are only active in certain areas of the intestines, represent only a few of at least 1,000 bacterial species within the mammalian intestinal tract, and typically are not present in the intestines in high enough densities to confer a health benefit.

The only way to potentially realize a health benefit is to regularly consume large numbers of the probiotic cells.

Prebiotics are non-digestible food ingredients, such as fibre, that feed beneficial micro-organisms in the large intestine.

Synbiotics combine prebiotics with probiotics for an additive or synergistic effect.

Regulatory oversight varies among countries from strict government regulations to buyer beware. In Canada, it’s mainly buyer beware, Inglis says. Health Canada currently considers prebiotics, probiotics and synbiotics as food ingredients and designates them as “generally recognized as safe,” meaning that they don’t need to go through an approval or registration process to reach the marketplace, especially those for livestock.

Research program

Changes are in the pipeline and companies here and in the U.S. are now in the process of voluntarily removing growth-promotion and feed-efficiency claims from labels on antimicrobials approved to be delivered in feed.

The first phase of their research was to understand how growth-promoting antimicrobials do what they do and then identify specific biomarkers to confirm those functions. They found that antimicrobials have beneficial effects that go beyond simple antimicrobial activity in the intestine.

Part of the work was developing sophisticated mouse models that mirror the workings of the bovine intestinal tract. The models are now being used to advance the project by testing the efficacy of new bio-products in development before eventually testing them in production settings.

“For example, we are looking at mitigation strategies to reduce inflammation in the gastrointestinal tract of cattle and reduce the potential of zoonotic pathogens that may be within cattle to become food safety issues,” Uwiera says.

Preliminary work involved recovering and studying bacteria from the bovine gastrointestinal tract to determine whether any could be used to deliver the bio-products. They found several novel bacteria that have promise.

Now, they are creating probiotics with the desired health effects by incorporating secretion of various bio-products into select bacteria and using the bacteria to produce the bio-products within the bovine intestinal tract.

“The probiotic will be the vehicle or organism to release compounds that reduce inflammation in the intestine and prebiotics will be the regulator to allow the probiotics to release their compounds in a regulated fashion,” Uwiera explains.

The project still has a few years to go. The new probiotics have to prove themselves in lab testing and then in clinical trials and finally on a feedlot scale to collect the bulk of science needed to make specific claims.

The research group won’t be taking the new products through commercialization but Uwiera says there’s definitely potential to patent and sell the intellectual property to a company that will be able to take this new science to the marketplace.

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