The use of antibiotics in livestock production has reshaped the farm for well over a half-century. While antimicrobial drug use for food-producing animals is below previous highs, efforts to further reduce the need for antibiotics play a key role in fighting antimicrobial resistance. The swine industry is central in the conversation about antibiotics’ importance, impact and sustainability.

Reducing the need for antibiotic use in livestock production is a key focus for researchers and on farms that has significant implications for the wellbeing of animals and humans alike.

Antimicrobial drugs have been widely used for more than six decades to treat bacterial infections, with lifesaving results. But antimicrobial resistance (AMR) threatens the efficacy of these drugs. In humans and livestock, excessive antibiotic use has enabled bacteria and fungi to develop a resistance to the antimicrobial drugs designed to kill them.

“Livestock animals can directly contribute the antimicrobial resistant genes to other animals and also to humans,” says Dr. Yanhong Liu, associate professor of animal nutrition at the University of California, Davis. “That’s a public health issue.”

The mutual health interests of humans and livestock with respect to antibiotic use were established in Stuart Levy’s landmark 1976 study showing “the spread of antibiotic-resistant organisms from chicken to chicken and from chicken to man.” This study illustrated the link between antibiotics given to livestock and the spread of antibiotic-resistant bacteria to humans.

Preserving the effectiveness of antibiotics

The Centers for Disease Control and Prevention (CDC) publishes Antibiotic Resistance Threats reports. The 2019 issue reported that there were 2.8 million antimicrobial-resistant infections in the United States annually, resulting in the deaths of more than 35,000 people. That figure was up from an estimated 23,000 deaths in the 2013 report. The declining efficacy of antibiotics reflects both human and livestock use, and people and animals alike have a role in preserving drugs that can provide lifesaving interventions.  

While the effort to reduce AMR is collective, the swine industry has potential to make a significant impact. According to the Food and Drug Administration, pigs account for about 40% of medically important antimicrobial drug use in food-producing animals in the United States.

“If we can reduce the need for antibiotic use in the swine industry, that is good not only for animals, but it has a huge benefit to humans and the public,” says Liu.

Focus upstream, not on the drug usage itself

Dr. Heather Fowler, director of producer and public health at the National Pork Board, believes the target for reduction is in reducing the need for antibiotics.

"I think it's one thing to say, 'We need to decrease our use of antibiotics,'" she says. "But we need to focus on more than the outcome alone and look upstream. We need to think about how we reduce our need for antibiotics, and that will have that ultimate outcome of also decreasing our overall use."

Stewardship, then, is utilizing all the tools available before there is a need for antibiotics.

Before turning to antibiotics

Biosecurity practices are designed to prevent the introduction and further spread of disease among the herd. They include practices such as setting up barriers to prevent infection transfer by removing potentially contaminated boots and clothing. The Danish-style bench or a simple piece of tape at the entry of the barn serve as a boundary, where boots remain on one side of the divide. Truck washes, boot washes and facility and equipment washes are important for sanitation. UV lights can be used to clean and disinfect products before humans enter.

“Producers recognize the need to do what’s right for people, pigs and planet,” Fowler says. “We are trying to use antibiotics appropriately to prevent resistance in our space but also recognizing resistance has no species barriers, so we’re really doing what’s right for everyone.”

Other preventive practices include vaccinations, ensuring access to clean water, reducing stress that makes pigs more vulnerable to sickness and breeding that takes into consideration production and health optimization. In the lab, researchers are working on ways to improve pigs’ gut health to boost their immune system. Each practice can reduce the need for antibiotics.

“Need drives use for antibiotics, so considering farm management practices to reduce need is key in reduction,” said Dr. Liu. “For example, improving hygiene and environmental conditions to prevent or reduce stress, improving feed quality and using vaccinations to eradicate specific diseases could all yield healthier herds. This will reduce our need for antibiotics, which reduces our impact on resistance.”

The impact of the FDA’s 2017 regulation

On January 1, 2017, a U.S. Food and Drug Administration (FDA) regulation took effect to stop the use of medically important antibiotics for growth promotion in food and animal production. This regulation transitioned access to feed and water-based medically important antimicrobial drugs from over-the-counter to requiring veterinarian prescription/oversight.

To adhere to the regulation, producers must work closely with veterinarians if an antibiotic is necessary to treat a disease, as well as keep records of any Veterinary Feed Directives (VFDs).

Since the regulation’s implementation, sales of medically important antibiotics approved for use in livestock have declined more than 38% from peak usage in 2015 to 2021. Total antibiotic sales decreased almost 29% in that period. But the increased need for antibiotics as a medical treatment since the change underscores the importance of preventive measures.

The incentive for farmers

Disease has a cost to producers, as it takes resources of time, labor and supplies to treat, and it slows overall production. Sick livestock often go off feed and subsequently miss benchmarks for average daily gains.

“Reducing antibiotic need by improving biosecurity and overall herd health is a win-win goal on the producers’ side,” said Dr. Liu. “First, reducing medical cost, second reducing the public concerns on the overuse of antibiotics in livestock. But the most important purpose for society is to reduce the development of antibiotic resistance.”

The future of antibiotic use

To ensure antibiotics are a resource for humans and animals for generations to come, the two sectors must practice responsible antibiotic use. Using the Centers for Disease Control and Prevention’s (CDC) One Health Approach, the two can collaborate for better solutions for animals and humans, with the aim of benefiting all species through best prevention practices and antibiotics use.

Why it matters

Antibiotics are a tool in the toolkit that may be the best option to attack a pathogen. Responsible use of antibiotics is paramount to preserve the efficacy of the drugs for both human and livestock use.

In 1942, 33-year-old Anne Miller became the first American patient to be treated with penicillin. She had been deathly sick with streptococcal septicemia for weeks before receiving the drug that was previously unavailable to civilians. In less than a day, her temperature went from about 105 degrees to returning to normal. Modern use of antibiotics had arrived. Miller lived until 90 years of age, a testament to a life-saving drug. Her story stands as a reminder of the value of carefully managing antibiotic use so the drugs may continue to be effective for people and animals.