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NC State Extension

Antimicrobial Resistance and Beef Cattle: A New Report

Originally published in January 2017 Carolina Cattle Connection

Recent federal regulations may have changed the way some producers do business in our industry. I have encountered many different opinions on this Veterinary Feed Directive running the gamut from misunderstanding to anger and frustration to indifference. Depending on your personal production philosophy, this change to medicated feed availability may or may not directly affect your cattle and ranch. However, the overarching effect on the industry may change production practices between segments to some degree. Smaller stocker and feedlot operations, which still manage the majority of feeder calves in our country, in the short term may change management practices as the VFD kinks are worked out. Overall, the beef industry is focused on pivoting away from antibiotic use in production. One of the main drivers behind negative public attitude toward production animal antibiotic use is media reports on antimicrobial resistance patterns in important coliform bacteria. These bacteria are commonly linked to fecal contamination of food products either from inappropriate sanitation in slaughterhouses, application of animal waste on field crops, or inappropriate sanitation or cooking procedures in restaurants or homes. This issue represents millions of dollars to industry and is heavily researched in both university and federal settings, and certainly represents one the biggest human health concerns for our country and global community.

The issue boils down to use of medically important antibiotics in food animals and their potential effect on bacteria that can infect humans. A medically important antibiotic is used both to treat human infections as well as animal infections. With the recently implemented FDA regulations, antibiotic delivery in feed or water is only deemed acceptable if a veterinarian has prescribed use of the product for the purpose of treating sick animals or protecting at-risk animals from getting sick. Prescriptions are intended to be very specific for a specified number of animals on a specific location and treatment time periods and drug amounts are very defined. Having worked primarily with the cow-calf industry during my career, I seldom encounter clients that use antibiotics for purposes other than treating sick individuals. The exceptions would be medicated milk replacers for orphaned calves or CTC in mineral for cattle on pasture, which have historically been used more liberally and perhaps without always having a true necessity for the product. Looking outside the Southeastern cow-calf segment, there are examples of antibiotic use that represent other production philosophies, however. Until 2015 we used some medically important antibiotics to alter rumen microbiota to improve weight gain efficiency and feed conversion. This practice, in theory, allowed us to keep heavily stocked systems healthier and certainly made them more efficient. However, this practice also dramatically increases the amount of antibiotic fed to animals en masse and is simply not going to be regarded as acceptable by the consuming public. It also, perhaps, can lead to higher selection rates of antibiotic-resistant bacteria in the GI tracts of the animals we produce. It’s a simple equation: exposing GI bacteria to drugs will kill all the bugs that are susceptible to these drugs leaving behind the ones that are resistant or unaffected by the drug. Those resistant bacteria, after a certain amount of time and continued exposure, will be the only ones left. Then, the domino effect of human exposure to these dangerous bugs becomes far more likely. This is certainly a simplified version of reality. There is no definitive research to show a cause and effect relationship between human infections with resistant bacteria and antibiotic use in food animals. Regardless, the ethos of antibiotic use is changing, and we all have to get on the bandwagon because of the potential risk we are creating by using antibiotics in the feed for beef calves. This is not a new issue; we have been moving towards mitigating the risk of creation and exposure for decades now through improvements in sanitation in both the slaughterhouse and post-harvest facilities, improvements in animal health technology pre-harvest, and educating the public about appropriate cooking and handling of meat products. So what does science say is happening in response to our efforts to control the risk? Antibiotics have certainly made our industry far more productive and efficient, and losing them represents a major loss of technology that could put large proportions of our industry in a world of financial hurt.

In a recently released report from The National Antimicrobial Resistance Monitoring System (NARMS) there is good news to be told! NARMS was established in 1996 as a partnership between the FDA, the Centers for Disease Control and Prevention, and the U.S. Department of Agriculture to track antibiotic resistance in foodborne bacteria. Since that time, they have reported trends in resistant bacteria in food products, production animal rearing facilities, and human infections. Depending on the pathogen, the news has often been alarming and indicative of the need for continued work or change in practices. This recent report documents data collected in 2014, so it does not document any changes related to GFI 213 or the VFD. You can view the full report on the FDA website at http://www.fda.gov/downloads/AnimalVeterinary/SafetyHealth/AntimicrobialResistance/NationalAntimicrobialResistanceMonitoringSystem/UCM528861.pdf.

In a nutshell, the report documents that recovery rates, or incidence, of antibiotic resistant isolates of several problematic bacteria have decreased in recent years from all sources (livestock, food, and humans). Significant reductions in resistant Salmonella species recovered from beef packing houses were reported (20% in 2010 to 7.6% in 2014). Multi-drug resistant Salmonella isolates from feedlots also declined in this last reporting interval: 67% in 2009 to 7% in 2014. Despite this bright and cheery news, in some populations of pathogens, resistance to certain drugs has increased or remained stable during the same time period. Of particular note is the increased percentage of isolates resistant to ciprofloxacin, the marker member of the fluoroquinolone class of antibiotics which are some of the newest and more highly restricted drugs available to our industry. 12% of Salmonella serovar Dublin isolates recovered from cattle and 9% of isolates from humans since 2004 have displayed resistance to this drug, which indicates a steady increase. A majority of those isolates were also resistant to cephalosporin antibiotics, another critically important class of antibiotics.

Food animal medicine has always been restricted when compared to other segments of the veterinary profession or our human-oriented counterparts. We have not only the health and well-being of our animals to contend with, but also the charge to protect the people who consume what we produce. The production of safe, wholesome, and enjoyable beef begins at the individual farm level. Practices that we employ as early as turning the bull out with our cows affects the final product either positively or negatively. When it comes to antibiotic use, we must be cognizant that every time we choose to use an antibiotic we are altering the potential safety of the product we are producing for our consumers. The decision to treat or not treat is important. We as an industry have made significant strides in the right direction, but there is still work to be done. I encourage each and every producer to develop or continue to maintain a relationship with a livestock veterinarian and have frank discussions about antibiotic use on your farm. This relationship will cost the operation some dollars, and in the current market, those are coming at a premium. In the overall cost analysis of the production unit, the “vet” cost category normally constitutes 10% or less. This includes product and services. Optimizing this cost unit will be very important for protecting your business as well as the overall health of our meat market share. Perhaps more importantly, the ability of medical doctors to treat infections for decades to come may in part rely on our responsible use of antibiotics in beef cattle. Some have said that we have entered the Post Antibiotic Era, meaning that the medical community has lost antibiotic technology for future treatment of bacterial diseases. This is a daunting and alarming thought, but at least for now the data is more positive than in previous reports from this reporting body.