I am back from my weeklong retreat to the rarefied atmosphere of Denver, CO, where I attended the Joint Annual Meeting (JAM 2010) of the Animal Science Societies. It is fair to say there was a lot going on with the conference, considering five animal science groups were represented there, resulting in a rather unwieldy web address and creating a big tent for folks from the poultry, swine, dairy and cattle, and even pet food industries to gather together. The scientific program for JAM 2010 can be found here.
There was a session at JAM2010 I found particularly interesting. Dr. Hyun Lillhoj, a researcher at the USDA ARS and past recipient of several PSA research awards, chaired a standing-room only session Tuesday entitled “Immunity, Nutrition, Genomics, and Gut Microbiota.” I found the session to be a good balance between the latest scientific techniques and more practical, “so why does it matter to me?” information. As has been noted before, antibiotic use in animal production is under much scrutiny in the US, with the FDA issuing a draft guidance on the use of antimicrobials in food producing animals earlier this year. Thus, the theory goes, the better we understand how antibiotics help or hurt the microbial population in the animal’s gut, the better we can develop effective ways to achieve the same outcomes with other, “kinder and gentler” products or procedures.
G. Donald Ritter, DVM, Director of Health Services at Mountaire Farms, talked about gangrenous dermatitis (“GD”) and how it is an “inside out” translocation of the bad bacteria Clostridium perfringens from the gut to the skin or other organs, where it “sets up shop, goes toxic and results in death of the chicken within a few days.” With the help of the nutrition company Danisco, Dr. Ritter analyzed the microbial flora of farms that were treated with anti-coccidiosis drugs or anti-coccidiosis vaccines (coccidiosis is a serious poultry disease caused by protozoan infections). He observed that the chickens on the vaccine-treated farms had more beneficial lactobacillus bacteria in their guts and less of the bad Clostridia bacteria. Of course, the key question is, were the beneficial lactobacillus promoting better gut health, or does a healthy gut promote the growth of lactobacillus?
To address more directly the question of whether good bacteria is cause or effect of good gut health, Dr. Matt Koci of NC State University presented results at the same session where he described supplementing chicken feed with a direct-fed “good bacteria” supplement (Primalac) and then proceeding to “poke it with a stick” by challenging those chickens’ immune system with the bad bacteria Salmonella enteritidis. Operating under the premise that an “overactive immune system eats first,” Dr. Koci found that adding the direct-fed microbial lowered the energy utilization of the birds immune system such that it was able to allocate more of its energy to growth and less to immunity. In a similar way, Dr. Lillehoj presented work done by her post-doctoral fellow at USDA on diet and gene interactions that looked at how bioactive plant extracts added to poultry feed influenced the expression of certain genes involved in the bird’s immune response.
I find the interactions between nutrition and gut health in animals to be a fascinating one, whether it is directly as a result of competitive exclusion in the gut by the “good bacteria” over the “bad bacteria” or that there are other, more subtle mechanisms at work, including immune modulators, beneficial peptides and/or “pre-biotic” nutrients. With the more sophisticated tools we have now (nutrigenomics, gene arrays, expression analysis, RFLP, etc.), much more information will be gleaned in the years ahead in this active and important area of research. Furthermore, it is exciting to think about how some of these interactions in animal systems can be translated into advances in the promotion of human health.
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