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Reducing antimicrobial use still key, says researcher

Cites consumer attitudes, lack of new products, need to reduce costs and need to improve animal health through better management.

The antimicrobial resistance study alleviates concern that antimicrobial use in cattle production is contributing to resistance that threatens human health today, but that shouldn't change the goal of reducing antimicrobial use in the beef industry, says Dr. Tim McAllister of Agriculture and Agri-Food Canada.

"It's important that this study didn't show any linkage to human health, because basically what it does is it buys us some time," says McAllister, a prominent southern Alberta beef researcher and part of the antimicrobial resistance study research team. "If we were in a situation where we had an immediate health concern, we'd probably be looking at having to remove the relevant antibiotics as soon as possible.

"As it stands, our goal is still to reduce the use of antibiotics in livestock production. There's no reason to still not have that as a goal. We're just lucky that we have some time to do that, as opposed to having an immediate health problem identified and having to do it tomorrow."

Prudent use remains crucial

While there are no resistance problems identified today, the principles of prudent antimicrobial use are crucial to avoid problems tomorrow, he says. The longer and more widely an antimicrobial is used, the greater the risk of resistance developing. Along with avoiding contributing to human health concerns, prudent use is also important to preserve the effectiveness of antimicrobials for veterinary use and keep production costs low.

"As it stands now, in many instances antibiotics are used as a crutch for some of the management practices we employ in feedlot cattle production," says McAllister. "By modifying these practices and exploring alternatives to preserve animal health, it's possible to dramatically lower the level of antibiotics that today's operations require. That's a goal we need to keep moving towards as an industry as it appears that is only a matter of time before consumers demand such changes"

Antimicrobial drugs are typically administered to healthy cattle upon entrance to feedlots to protect animal health and promote growth. The drugs are administered at subtherapeutic levels - in other words, at levels below those used to treat sick animals, but with enough dosage to protect against infection. This use of antimicrobials helps the animals cope with the inherent disease risks associated with the stress and dramatic dietary and environmental changes that occur upon introduction from the range to the feedlot.

"There are management practices that we could employ where we could still put those animals into a situation in a manner that wouldn't increase their risk to diseases as much as it does now," says McAllister. "There are also nutritional options that we're looking at, such as priobiotics and proper dietary introduction when cattle first enter the feedlot, which could greatly reduce the need for antimicrobials."

Absence of new products

In addition to examining the above factors, McAllister and colleagues are looking into how antibiotics change feeding behavior. "Once we define how the antibiotics change feeding behavior, then we can look for other feed additives or other management practices that mimic those same changes."

There's no doubt there are many challenges to changing current feedlot regimens, but the industry must steadily move down that road, says McAllister. The most blunt reason is that the prospects are slim for new antimicrobial drugs approved for use in cattle production. As the current generation of drugs loses its effectiveness, the industry will have no choice but to rely on alternative practices.

"Obviously, if we had a bunch of new products coming out regularly than we could frequently change antibiotic therapies, a strategy that can reduce the development of resistance," says McAllister. "But the likelihood of that is extremely slim, because of the regulatory hurdles, and because of the relatively small amount of money that the use of antibiotics in livestock accounts for as compared to their use in human medicine.

"Many pharmaceutical companies are naturally much more focused on human medicine products as this is where the majority of their revenue arises from. Also, because they recognize the resistance issue, these companies don't want the products they're developing for human medicine used in livestock production, because they don't want to compromise the effectiveness of those products."

Consumers want change

Consumer attitudes are further driving antimicrobials out of the livestock production picture, he says. "Consumers increasingly don't want the animals they consume fed antibiotics of any kind, irrespective of a human health issue."

The quest to develop antimcrobial alternatives has uncovered some promising tools, such as bacteriophages and nutraceuticals, but nothing as yet has made a big impact. "The problem is for now, many of the alternatives that are presently available are not near as good as the antibiotics that are presently on the market," says McAllister. But he believes that can change with a long-term investment in research and development.

"You have to put the current situation in the context that millions and even billions have been spent on the development of the antibiotics we use today. Billions of dollars have not been spent on the development of these alternatives."

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