The use of antibiotics in livestock farming has transformed the industry over recent decades, fuelling productivity gains as agriculture races to keep up with a growing global population and rising demand for animal-source foods.
These drugs, once hailed as miracle cures, help keep animals healthy, prevent infections and even boost growth rates. But there’s a flipside: the overuse and misuse of antibiotics – in both humans and animals – are contributing to a growing public health crisis.
Antimicrobial resistance (AMR) — which includes bacterial antibiotic resistance — occurs when bacteria, viruses or other microbes evolve to resist the drugs designed to kill them.
According to the World Health Organization (WHO), AMR is now “one of the top global public health and development threats.”
And the numbers paint a stark picture. In 2019, 1.27 million people died directly from drug-resistant infections, with 4.95 million deaths linked to AMR. Looking ahead, estimates suggest up to 39 million deaths could result from bacterial AMR alone between 2025 and 2050.
In response, global leaders at the 2024 High-Level Meeting on AMR during the 79th UN General Assembly agreed to significantly reduce the use of antimicrobials in the agri-food system.
“In the century since Alexander Fleming stumbled across penicillin in a laboratory in London, antibiotics have become a mainstay of medicine, transforming once-deadly infections into treatable and curable conditions,” WHO Director-General Dr Tedros Adhanom Ghebreyesus said in a statement at the time.
“Antimicrobial resistance threatens to unwind that progress, making it without question one of the most pressing health challenges of our time."
So how are we doing? According to a new study published in Nature Communications, not great.
Researchers led by Alejandro Acosta, a livestock economist policy officer at the UN’s Food and Agriculture Organization, estimate that if current trends continue, global antibiotic use in livestock could rise by nearly 30 per cent by 2040, compared to 2019 levels. That’s despite high-level pledges to bring usage down.
Their projections show that under a “business-as-usual” scenario – with both livestock numbers and antibiotic use intensity (the amount of antibiotics used per unit of animal biomass) following current trends – antibiotic use could reach over 143,000 US tons annually by 2040.
“I believe that society is at somewhat of a crossroads,” Acosta told BBC Science Focus. “On the one hand, we need to increase food supply to meet the growing demand for animal protein. On the other hand, we need to decrease the use of antimicrobials."
The team explored several alternative scenarios. Encouragingly, they found that reducing antibiotic use intensity by just 30 per cent, combined with improvements in productivity that reduce overall livestock biomass, could offset the expected increase in antibiotic demand.
In the most ambitious scenario – a 50 per cent reduction in antibiotic use intensity, again paired with better productivity – total antibiotic use in livestock could fall by more than half to around 62,000 tons a year by 2040.
“We’re not just projecting numbers – we're helping decision makers to understand where antibiotic use in livestock is heading if we don’t act now,” Acosta said. “Perhaps the true value of this paper is that we are able to show what will happen if we don’t translate political commitment into practical action.”
The study also highlights major regional disparities. By 2040, Asia and the Pacific are expected to account for 65 per cent of global antibiotic use in animals, with South America contributing around 19 per cent. But Africa is where growth is set to be fastest, driven by rising populations and increased meat consumption.
“Politically, we have seen a number of declarations on this,” Acosta said. “However, we see that the trend indicates that antimicrobial use might increase. So it seems like a challenge – countries are committing to reduce the need for antimicrobials but the numbers are showing that the system is moving in a different direction.”
So what’s the solution?
According to Acosta, it’s not just about clamping down on antibiotic use. Productivity is the key – more milk, more eggs while using fewer resources like land and energy. He claims this is more than possible with smarter farming practices, such as through better animal nutrition.
But the ultimate solution, he said, requires a much more holistic approach – from investment in water systems to education of the farmers themselves.
The study stresses that “optimising livestock biomass” is crucial. That means enhancing efficiency, improving animal health and welfare, all with a focus on “increasing productivity per animal rather than expanding herd sizes.” This, the authors wrote, is especially critical in middle- and low-income countries, where livestock farming plays a vital role in food security and economic stability.
In short, there’s no simple fix – and no silver bullet on the horizon.
“We are talking about one of the most challenging issues that society will face in the coming years,” Acosta said. “What will happen if antibiotics stop working? It’s a puzzle that needs to be solved – how can we ensure that the health threat doesn’t become a reality while continuing to produce food at a price that consumers can afford, especially in developing countries?”
About our expert
Alejandro Acosta is a livestock economist policy officer at the UN’s Food and Agriculture Organization with more than fifteen years of experience conducting quantitative economic policy analysis and supporting the formulation and implementation of investment programs in various developing regions, including specific field positions in Europe, Australia, Southern Africa and South America.
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