Reducing the Use of Antibiotics in Farm Animals

In January 2018, a report released by the World Health Organization’s newly minted Global Antimicrobial Surveillance System revealed widespread antibiotic resistance among people with suspected bacterial infections in nations around the world. Commenting on the report, Dr. Marc Sprenger, director of WHO’s Antimicrobial Resistance Secretariat, stated, “Some of the world’s most common—and potentially most dangerous—infections are proving drug-resistant.” 

The danger of this is enormous—and could get much worse. According to an April 2019 report prepared for the United Nations by the Interagency Coordination Group on Antimicrobial Resistance (IACG), “Drug-resistant diseases already cause at least 700,000 deaths globally a year.” It warned that without a sustained effort to contain antibiotic resistance, this figure “could increase to 10 million deaths globally per year by 2050” and trigger catastrophic economic shocks. 

So where are all these resistant bacteria coming from? Consider where antibiotics are most used: A 2015 study (Van Boeckel et al.) indicated that, worldwide, antibiotics are more likely to be administered to farm animals than to humans. In the United States, it is far more likely. According to a 2015 study published in the American Journal of Public Health, “Of all antibiotics sold in the United States, approximately 80% are sold for use in animal agriculture; about 70% of these are ‘medically important’ (i.e., from classes important to human medicine).”

The twist is that in animal agriculture, most antibiotics are not used for targeted disease treatment—that is, to treat individual animals who have been specifically diagnosed with a bacterial infection. On farm animals, they are often administered more broadly to control disease, prevent disease, and—most controversially—promote growth.

In disease control, once one or more animals has been diagnosed with a bacterial infection, the entire herd or flock may receive antibiotics to prevent more animals from becoming infected. Disease prevention takes it one step further: In this case, antibiotics are preemptively administered to animals during times of stress—when their immune systems are suppressed and they are thus more susceptible to bacterial infections. Within industrial agriculture operations, animals are routinely dosed with antibiotics to counter the stressful, crowded low-welfare environments to which they are condemned. 

But the real revolution for antibiotics in agriculture came in 1950, when scientists at Lederle Laboratory in New York discovered—somewhat by accident—that low, “subtherapeutic” doses of antibiotics added to chicken feed accelerated growth. From that point forward, farmers began adding tiny amounts of antibiotics to animal feed. Over the decades, across an ever-expanding industry, those tiny amounts have added up to a lot of antibiotics. 

Today, however, the use of antibiotics to promote growth is increasingly viewed as an unacceptable risk. The IAGC report states that antibiotic use to promote growth and prevent (rather than treat) disease in healthy animals is “further contributing to the development and spread of antimicrobial resistance.” As explained by the Centers for Disease Control, “When animals are given antibiotics for growth promotion or increased feed efficiency, bacteria are exposed to low doses of these drugs over a long period of time. This is inappropriate antibiotic use and can lead to the development of resistant bacteria.” It appears the descendants of those 1950 chickens are coming home to roost—with antibiotic-resistant bacteria in tow. 

Animal products are, in fact, one of the ways antibiotic-resistant bacteria get transmitted to humans. In recent years, Consumer Reports has tested hundreds of packages of supermarket meat, poultry, and shrimp (which, if farmed rather than wild caught, may have been dosed with antibiotics). It found antibiotic-resistant bacteria in 14 percent of beef, 14 percent of shrimp, 57 percent of chicken, and 83 percent of turkey samples tested. Proper food safety practices can help reduce this exposure. But changing the way we use antibiotics in livestock can also help. The 2005 US ban on the use of fluoroquinolones in poultry production, for example, significantly decreased the occurrence of fluoroquinolone-resistant Campylobacter infections in humans. 

The use of antibiotics for growth promotion has now been outlawed in dozens of countries worldwide, including those within the European Union. However, a 2018 report by WHO, the UN Food and Agriculture Organization, and the World Organisation for Animal Health indicated that across the globe, only 42 percent of countries have limited antibiotic use for growth promotion. WHO “strongly recommends an overall reduction in the use of all classes of medically important antibiotics in food-producing animals, including complete restriction of these antibiotics for growth promotion and disease prevention without diagnosis.”

In the United States, the Food and Drug Administration implemented a voluntary plan in 2013 for pharmaceutical companies to remove information from their product labels on use for growth promotion. The FDA has since banned outright the use of antibiotics for growth promotion in feed or drinking water and stipulated that a valid veterinary-client-patient-relationship is required for all antibiotics administered to livestock in feed or water to combat disease. This regulation, known as the Veterinary Feed Directive (VFD), went into effect on January 1, 2017. Under the VFD, a prescription from a licensed veterinarian—one who has seen the animals within the past 12 months—is required for all antibiotics added to livestock feed or drinking water. This is a significant regulatory change, as livestock producers previously could purchase antibiotics over the counter without veterinary oversight.

This has led to dramatic changes in the sale and use of medically important antibiotics intended for use in food-producing animals in the United States. The latest FDA report shows a 33 percent reduction in the quantity of these antibiotics sold between 2016 and 2017, and a 43 percent reduction since 2015, when antibiotic sales were at their peak (see graph above).

The VFD appears to have caused producers and veterinarians alike to reframe their thinking around antibiotics. As Dr. Glenn M. Rogers, president of the American Association of Bovine Practitioners, said in 2018, “Antimicrobials are a necessary tool to use appropriately when a failure occurs somewhere in the production system. Over-reliance on antimicrobials or incorporating them as a crutch for poor management should not be an acceptable option.” 

A focus on preventative medicine, low-stress handling, nutrition, and effective herd/flock management can all help reduce antibiotic use. The fact is, better animal welfare goes hand in hand with more responsible use of antibiotics by the animal agriculture industry—which in turn will help preserve the antibiotic safety net upon which we, as humans, have come to depend. 

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