The Link Between Antibiotic Resistance and Factory Farming

factory farm pig

Soon after he is born, a suckling pig on a factory farm receives his first antibiotic—oxytetracycline—as a preventive against infective enteritis. Within the next few hours, the pig undergoes processing, which involves having his ears notched and testes removed without sedation or painkillers. Twenty days later, he is weaned from his mother and removed from her to a transition crate, where he receives more antibiotic drugs in his formulated, pretreated feed. The piglet’s immature, stressed immune system makes him susceptible to bouts of diarrhea, the first in a long series of illnesses to which he is vulnerable on a high-density factory farm.

After another dose of antibiotics to treat the post-weaning diarrhea, he is moved to a nursery, where he is one among many housed in crowded, unsanitary conditions. He remains there for two to three months and is fed antibiotic-rich feed and water, which are meant to protect him and the herd from a host of infectious diseases such as meningitis, greasy pig disease, and more diarrhea. Continually receiving medicated feed enables the piglet, within six months of birth, to attain his target weight, at which point he is considered “slaughterhouse-ready.”

Farmed Animals and Antibiotics

Factory-farmed animals of all species receive a variety of antibiotic drugs aimed at maximizing their economic productivity. Antibiotics, which can be naturally-occurring or synthetic compounds, speed farmed animals’ growth and prevent the onset and spread of bacterial infections; they are frequently administered to otherwise healthy animals. The prolific use and abuse of antibiotic drugs by factory farms is contributing to the rapid global growth and spread of antimicrobial resistance (AMR). The term AMR, which is defined as the resistance of microorganisms such as viruses, fungi, or bacteria to treatment by any common medication, is often used to refer specifically to the resistance of infectious bacteria to treatment by antibiotic medicines.

The alarming growth of antibiotic-resistant bacteria has prompted the World Health Organization (WHO) to recommend that factory farms stop routinely administering antibiotic drugs to healthy animals. Antibiotics, when not administered excessively, are extremely effective at saving the lives of human and non-human animals; they are the ultimate defense against bacterial infections. However, frequent overuse and misuse of critical antibiotic drugs, primarily via their intensive use in factory farms, is increasingly giving rise to “superbugs”—antibiotic-resistant bacteria that do not respond to treatment by traditional antibiotic medicines. The excessive use of antibiotics by factory farms poses a major risk to humans and other species worldwide as superbugs continue to multiply and spread.

Which Antibiotics Do Farmers Use, and Why?

Farmers rely on a plethora of antibiotics to ensure the efficient and profitable operation of factory farms. Penicillins, tetracyclines, sulphonamides, cephalosporins, quinolones—over 100 different antibiotics are available for farmers’ use. Animals on U.S. factory farms consume over 80 percent of the nation’s antibiotics; a nine percent rise in the sale of antibiotics used in U.S. animal feed between 2017 and 2018 indicates that antibiotic usage by factory farms is still increasing.

Subtherapeutic doses of antibiotics—doses smaller than the amounts required to treat diseases—are frequently administered to healthy farmed animals to promote faster growth and induce weight gain. Regular, or therapeutic, doses of antibiotics are also routinely administered as preventative measures to control the outbreak and spread of infectious diseases, to which farmed animals are highly susceptible as a direct result of intensive farming practices. Factory farmers rely heavily on antibiotic drugs because their administration is the most efficient way to maximize the profitability of each sentient creature while maintaining them in inhumane, crowded conditions.

Increasing Efficiency

Low doses of antibiotics incorporated into the diets of farmed animals are economically profitable specifically because they improve feed efficiency and enhance the quality of animals’ meat. Studies show that the daily weight gains of farmed animals fed antibiotic-supplemented diets can be as much as 10 percent greater than the weight gains of animals fed antibiotic-free diets. Pigs whose diets are supplemented with antibiotics require 10-15 percent less feed to achieve their target weights of typically 250-280 pounds; antibiotics enable “speed-breeding” of pigs in time spans of less than six months—a mere fraction of the species’ natural lifespan of 15-20 years.

Antibiotic-fed animals also produce meat of better quality with less fat and higher protein content as compared to animals whose diets are not supplemented with antibiotics. Adding antibiotics to chicken feed increases the rate of egg production and improves eggs’ ability to hatch while reducing the occurrence and spread of infections among chickens. Antibiotic drug usage by factory farms is a calculated, cost-effective investment designed to lower the risk of disease outbreaks while inducing livestock to gain weight more rapidly with less food. 

Filthy Conditions

In addition to increasing feed efficiency and the meat quality of farmed animals, antibiotics in factory farm settings are often used in lieu of maintaining hygienic farming operations. By design, high-density farms house livestock in closely confined quarters. The unnaturally stressful conditions compromise farmed animals’ immunity and render them vulnerable to a variety of infectious diseases. The crowded, dark, unhygienic stalls that house intensively-farmed animals are some of the dirtiest environments on the planet; these stalls often contain excessive quantities of the animals’ urine and feces. The animals, plied excessively with antibiotics to maintain some semblance of good health, are housed as minimally and cheaply as possible to maximize their profit margins. 

Unlike traditional farming practices that rely primarily on human labor to maintain reasonably sanitary environments for farmed animals, factory farms’ costs are concentrated in capital-intensive infrastructure and equipment. Stalls, cages, fossil fuels, and drugs are prioritized to run factory farm operations over comparatively more expensive human labor. Under these circumstances, antibiotic drugs are the perfect antidote to temporarily maintain animal health, reduce labor costs, and maximize profits.

Farmers are further motivated to rely heavily on antibiotics because often the same drugs that enhance farmed animals’ growth can effectively prevent the proliferation of infectious diseases. These incentives, combined, have encouraged the dramatic increase of antibiotic use by factory farms while enabling the farms to densely pack living beings into highly stressful, unsanitary environments.

Treatment-Resistant Bacteria

Not surprisingly, bacteria on factory farms are plentiful. The routine exposure to low doses of commonly prescribed antibiotic drugs enables some strains of bacteria to become immune to treatment; this treatment resistance can result in the unmitigated spread of bacterial infections and diseases. The infections and diseases produced by antibiotic-resistant bacteria require progressively stronger antibiotics for effective treatment, setting off or further escalating an unwinnable cycle that calls for newer and stronger drugs to fight increasingly treatment-resistant bacteria.

The treatment-resistant bacteria can also transfer its genetic material to other strains of bacteria, thereby spreading antibiotic-resistant genes to new and different bacterial colonies. Antibiotic-resistant bacteria can travel with ease from animal to animal or from animal to human and then human to human; humans can also contract treatment-resistant bacterial infections by directly handling or consuming raw or undercooked animal products that have been exposed to antibiotics.

The routine, excessive use of antibiotic drugs by factory farms has triggered a cycle that results in the continual need for more potent antibiotics to fight dangerous infections in both humans and animals. The continuation of the cycle is resulting in the evolution of increasingly more antibiotic-resistant bacteria.

When Bacteria Spread From Farms to Humans

Bacterial strains that emerge regionally on factory farms are capable of spreading across borders and continents as people, animals, and goods travel. In 2019, the WHO listed antimicrobial resistance, along with global influenza pandemics and climate change, as being among the top ten global threats to human health. Each year, antibiotic resistance results in over 700,000 human deaths worldwide; more than 10 million people are projected to die annually from treatment-resistant bacteria by 2050. In the U.S. alone, antibiotic-resistant bacteria claims a life every 15 minutes and is annually responsible for more than 2.8 million infections and 35,000 deaths.

In an attempt to curb the alarming growth of antibiotic-resistant bacteria, the WHO in 2017 released a document titled, “Guidelines on Use of Medically Important Antimicrobials in Food-Producing Animals.” Based on scientific evidence, these guidelines demonstrate that the overuse of antibiotic drugs in farmed animals is contributing to the widespread emergence of antimicrobial resistance. The guidelines are aimed at preserving the effectiveness of “critically important antibiotics” for human illnesses by reducing their unnecessary and indiscriminate use in farmed animals. The WHO Advisory Group on Integrated Surveillance of Antimicrobial Resistance regularly publishes updated lists of critically important antimicrobials for humans in an attempt to both slow the growth rates of treatment-resistant superbugs and maintain the efficacies of antibiotic drugs that treat fatal infections.

Despite these clear, science-based recommendations, factory farms around the globe continue to conduct “business as usual.” The risks are known—yet factory farms continue to excessively treat animals with antibiotics to maintain highly efficient, unsanitary operations. Emerging treatment-resistant bacteria continues to pose a significant and increasing global public health risk.

Antibiotics and the Environment

Excessive antibiotic use by factory farms negatively affects ecosystems, too. Antibiotic drugs are routinely released in high quantities into the environment via farms’ manure and wastewater streams. Given their concentrated manner of operations, factory farms generate significant quantities of animal waste. In the U.S., a factory farm with 800,000 pigs can annually produce more than 1.6 million tons of biological waste, which consists of manure, urine, and afterbirth such as the placenta and sac. U.S. factory farms collectively generate two billion tons of manure and liquid waste each year. Animal waste on factory farms is typically stored in tanks and massive, open-air cesspools, which are often poorly engineered and prone to leaks and spills. Considering that farmed animals discharge via urine and feces up to 90 percent of the antibiotics that they receive, factory farms’ biological waste is heavily concentrated with still-potent antibiotic drugs.

Application of farmed animals’ manure in agricultural fields routinely occurs by factory farms, resulting in farm soils becoming prime breeding grounds for antibiotic-resistant bacteria. The antibiotic-resistant bacteria in manure, by interacting with soil-dwelling bacteria, can transfer its treatment-resistant genes to new bacterial strains, thereby increasing the prevalence of antibiotic-resistant bacteria in food crops. Antibiotic-resistant bacteria in manure and soils can also spread into the air and leach into groundwater and waterways, causing harm to aquatic life and degrading water quality. The sheer volume of waste generated by factory farms and the often-lacking containment infrastructure, combined with the customary practice of applying animal waste to soil, significantly enables the spread of antibiotic-resistant bacteria from factory farms to the environment at large.

Regulatory Shortcomings

Lax regulatory oversight regarding the use of antibiotic drugs by factory farms further enables the ongoing growth and spread of antibiotic-resistant bacteria. European Union regulations banned factory farms’ use of antibiotic drugs as growth promoters in 2006. The U.S. Food and Drug Administration (FDA) in 2017 issued similar, though non-legally-binding, guidelines; the intent of the guidelines is to decrease the administration to farmed animals of growth-promoting antibiotics that are important to human health. But since many of the antibiotic drugs used to accelerate the growth of farmed animals can simultaneously prevent infectious diseases, both the European Union regulations and the FDA guidelines are easily circumvented.

The overuse of antibiotic drugs continues as both American and European factory farms choose to exploit the obvious loopholes. Clearly, in the U.S., stronger measures than non-legally-binding guidelines are needed to enforce changes to antibiotic use by factory farms; the lack of regulation, oversight, and enforcement also means, as the Centers for Disease Control and Prevention admits, that the term “antibiotic-free” on food labels is not USDA-approved and has no single definition or clear meaning.

The existing environmental protection laws are also insufficient and poorly enforced, failing to properly manage the copious amounts of antibiotic-laden animal waste that farming operations generate. The result is that factory farms legally pollute the soil, air, and water in their vicinities with increasing levels of antibiotic-resistant bacteria. The severe lack of regulations governing the use of antibiotic drugs by factory farms and the poor enforcement of existing regulations—regulations necessary to prevent both widespread public health crises and harmful environmental impacts—are recurring themes in the fight against growing global antibiotic resistance.

Increasing Demand for Antibiotics

Antibiotic drug use by factory farms is poised to increase as farmers strive to boost their productivity to meet the ever-increasing global demand for meat and dairy. In the U.S., where factory farms produce 99 percent of the nation’s animal products, the estimated combined production of beef, pork, and poultry reached a record quantity of 26.9 billion pounds in the first quarter of 2020. Globally, the meat and dairy industries are currently worth over $2 trillion dollars and are expected to experience record growth in the coming years. The rising affluence of nations in Asia, Africa, and the Middle East is a major driver of the steady increase in meat consumption worldwide.

China’s demand for pork, in particular, has dramatically increased within the past few years; the nation’s people now annually consume 55 million tons of pork, equal to approximately half of the pork produced globally each year. Not coincidentally, China is also the world’s largest consumer of agricultural antibiotics, requiring an estimated 162,000 tons of these drugs per year. As antibiotic drug use by factory farms rises in parallel with the growing global demand for meat and dairy products, the prevalence of antibiotic-resistant bacteria will likely also continue to increase.

Antibiotics and COVID-19

The COVID-19 disease caused by the virus SARS-CoV-2 illustrates the importance of humans’ access to antibiotics that can effectively treat and control the spread of infectious bacterial diseases. Patients diagnosed with COVID-19 are more susceptible to secondary illnesses caused by bacteria, such as pneumonia; such secondary bacterial infections, acting on the patients’ already-weakened immune systems, are more likely to be fatal. Up to 50 percent of COVID-19 patients who die incur secondary bacterial infections. During the 2009 H1N1 viral flu pandemic, secondary bacterial infections occurred in up to 55 percent of the 300,000 fatalities.  Secondary bacterial pneumonia caused a significant number of the deaths associated with the 1918-20 H1N1 flu pandemic.

Humans’ increased susceptibility to fatal bacterial infections during viral epidemics and pandemics has prompted the National Institutes of Health to state that the “preparations for diagnosing, treating, and preventing bacterial pneumonia should be among the highest priorities in influenza pandemic planning.” Prevalent antibiotic-resistant bacteria during pandemics, by decreasing or voiding treatment efficacies, significantly worsen clinical outcomes from such infections. An arsenal of effective antibiotics is the best line of defense that humans have against life-threatening flu pandemics.

The Ongoing Public Health Threat

Ignoring the link between the abuse of antibiotic drugs by factory farms and the aggressive growth of antibiotic-resistant bacteria is short-sighted. An abundance of evidence reveals the risks that intensive factory farming inherently poses to humans, animals, and ecosystems; yet a lack of meaningful regulation and the growing demand for animal products is enabling factory farms to continue to grow unimpeded. The abuse of farmed animals is not only dangerous to public health globally but also inhumane and unethical.

As sentient beings ourselves, humans have the capacity to treat other living creatures with compassion and kindness without any ulterior motives. Perhaps it will take the advent of another, even deadlier pandemic before we seriously reckon with our food system’s overreliance on antibiotics and the tortuous existences to which we subject other animals. But, by then, as dangerous superbugs continue to multiply, it may be too late.