Antibiotic resistance poses a great threat to global human health. This article explores the impact of modern farming practices on animal welfare and the industry’s consequential misuse of antibiotics.
Since their introduction to human medicine in the 1940s, antibiotics have become a cornerstone of modern medicine and helped save enormous numbers of lives.
Antibiotics are not only used to treat patients that have a bacterial infection, they are essential for preventing infections in those undergoing life-saving procedures like cancer chemotherapy, organ transplants or caesareans, or other types of major surgery.
The threat of antibiotic resistance
Unfortunately, according to the World Health Organization, the rise of antibiotic resistance, which occurs when bacteria evolve to resist the action of antibiotics, threatens many of the gains of modern medicine. The WHO says it is one of the top global public health and development threats.
Antibiotic resistance is not merely a threat for the future, it is already here today and having a major impact. According to the first comprehensive assessment of the global impact of antibiotic resistance, published in 2019 in The Lancet journal, the deaths of 1.27 million people a year are directly attributable to antibiotic resistance, and 4.95 million deaths a year are associated with antibiotic resistance (1).
The origins of resistance
Increasing levels of resistance are due to the use and overuse of antibiotics. Excessive antibiotic use increases the selective pressure on bacteria to evolve resistance, as sensitive bacteria are killed off, and resistant ones survive, multiply and spread.
The main cause of resistance in most human infections is the use of antibiotics in human medicine, but we know that the overuse of antibiotics in intensive livestock farming is also contributing.When antibiotics are overused in farm animals, bacteria in their guts, or on their skin, develop resistance, and these can spread to humans through the food chain, the environment, or by direct contact. This occurs for a wide variety of infections, including typical food-poisoning bacteria like Salmonella or Campylobacter, the increasingly resistant E. coli, which is responsible for thousands of deaths in the UK each year (2), or for well-known superbugs like MRSA or Clostridium difficile.
Antibiotic use in agriculture
In many countries, data on antibiotic use is poor, but it is estimated that globally about two thirds of all antibiotics are used in farm animals (3), with the percentage in the UK being lower at about 30% (4). Much of this farm antibiotic use is inappropriate and avoidable. Far too often antibiotics are given to groups of animals, in feed or drinking water, to control the spread of diseases which occur in the stressful and unhygienic conditions in which many intensively farmed animals are kept. This occurs particularly for pigs and poultry, but also in some countries in cattle.
The Alliance to Save Our Antibiotics is an alliance of health, medical, civil-society and animal-welfare groups that was founded by Compassion in World Farming, the Soil Association and Sustain, to campaign to stop the overuse of antibiotics in livestock farming. Our latest report (5), published in February, shows that some significant progress towards reducing farm antibiotic use is being made in the UK, and in many other European countries, but that far more needs to be done to achieve truly responsible use.
UK farm antibiotic use has fallen by 59% since 2014, which is good news, but unfortunately 75% of that use is for group treatments (6). This means that antibiotic use is still not sufficiently targeted and that these hugely important medicines are still being used to prop up farming systems which are causing too many animals to fall sick. In Norway, Iceland, Sweden and Finland, the European countries with the lowest farm antibiotic use, group treatments only account for between 10% and 27% of total use (7). One reason for this is that these Nordic countries have some higher animal-welfare standards, particularly in the pig industry, and this means that illness is not as widespread and treatments can be more frequently aimed at individual animals.
What legislation supports a change in agricultural antibiotic use?
Fortunately, the regulation of farm antibiotic use is improving. On 17 May 2024, new legislation came into force in the UK that is aimed at achieving more responsible antibiotic use. Using antibiotics “routinely” has finally been banned (8). Preventative antibiotic use has also been restricted to exceptional cases where the risk of an infection or of an infectious disease is very high and where the consequences of not prescribing the product are likely to be severe.
These are welcome measures and should contribute to some further reductions in antibiotic use. The new rules are based on regulations the European Union introduced on 28 January 2022. Unfortunately, despite the British government having previously said that it intended to fully align with the EU legislation, some very important aspects of the EU regulations have been dropped (9). In particular, the UK government has refused to ban purely preventative group treatments, as the EU has done. This is a major loophole which will allow some farms to keep on misusing antibiotics.
The British government has also refused to introduce statutory antibiotic-use data collection by farm-animal species. The EU began collecting such data last year, but the UK has decided to rely instead on data collected voluntarily by farming organisations, which does not cover all farms. The fact that the UK has chosen to fall behind the EU on this critical issue is very disappointing as having comprehensive and reliable data is important for understanding and reducing the spread of antibiotic resistance.
The new UK legislation will ban using antibiotics to compensate for poor hygiene, inadequate animal husbandry, or poor farm management practices, as the EU has already done. On paper, this sounds like excellent news, and it will be if fully implemented in practice. However, proper implementation of this rule would require major improvements to animal husbandry, and there is little evidence that this is happening.
Animal welfare in modern farming practice
As our report shows, many current farming practices are actually causing animals to fall sick and are linked with antibiotic overuse. High levels of stress, poor hygiene caused by high numbers of farm animals kept indoors in close confinement, and inappropriate diets all contribute to the emergence and easier spread of intestinal and respiratory disease and to the need for antibiotic use. The early weaning of piglets, which can be legally weaned as early as 21 days, can cause post-weaning diarrhoea and is a major reason for high antibiotic use in the pig industry.
Modern farm-animal breeds are often selected to increase productivity, but this can lead to numerous health and welfare problems and higher antibiotic use. The growth rate of modern broiler chickens has quadrupled since the 1950s, and intensively farmed chickens are now slaughtered when they are just 28 to 42 days old (10). Data from the Netherlands shows that fast-growing chickens receive 6 to 9 times more antibiotics than slower-growing birds because of their health problems (11).
Sows are being bred to produce ever-increasing numbers of piglets. The most productive UK sows now produce an average of 17.16 piglets a litter and 37.56 live piglets a year (12). Such hyper-prolific sows may not have enough teats and can struggle to produce enough milk for all their piglets, making early weaning necessary.
British dairy cows produced an average of 8,163 litres per cow in 2022, up from 5,151 litres in 1990 (13), and compared with a global average of about 2,500 litres (14). Genetic selection for high milk yield is positively correlated with the incidence of lameness, mastitis, reproductive disorders, and metabolic disorders, conditions frequently requiring antibiotic treatment.
Unfortunately, despite the overwhelming evidence showing that modern farming practices, and poor hygiene and high levels of stress are associated with more disease and greater need for antibiotics, the government is still not planning any improvements to minimum husbandry standards. This raises serious questions about whether we can really expect the use of antibiotics to compensate for poor hygiene and inadequate animal husbandry to end.
Improve animal welfare to protect our antibiotics
Undoubtedly, progress has been made in tackling some of the worst misuses of antibiotics in British farming, but stricter rules are still needed. The UK would do well to align with the EU and prohibit all prophylactic group treatments. Introducing statutory antibiotic-use data collection would also support regulation to attenuate antibiotic misuse.
Yet, ultimately, to address the many causes of farm animal ill health we need to fundamentally change our approach to farming. Farm animals deserve to be kept in far less stressful conditions, where their health and happiness are given real priority. And consumers will also need to accept that protecting our antibiotics, and farming animals more humanely, will mean less, but higher-quality and healthier animal foods.
References
- Antimicrobial Resistance Collaborators, 2021. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis, The Lancet, https://www.thelancet.com/journals/lancet/article/PIIS01406736(21)02724-0/fulltext
- Official Statistics 30 day all-cause mortality following MRSA, MSSA and Gram-negative bacteraemia and C. difficile infections: 2022 to 2023 report Updated 9 November 2023, https://www.gov.uk/government/statistics/mrsa-mssa-and-e-coli-bacteraemia-and-c-difficile-infection-30-day-all-cause-fatality/30-day-all-cause-mortality-following-mrsa-mssa-and-gram-negative-bacteraemia-and-c-difficile-infections-2022-to-2023-report
- Tiseo et al., 2020. Global Trends in Antimicrobial Use in Food Animals from 2017 to 2030, Antibiotics, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766021/pdf/antibiotics-09-00918.pdf
- Veterinary Medicines Directorate and UK Health Security Agency, 2023. UK One Health Report: Joint report on antibiotic use, antibiotic sales and antibiotic resistance, https://www.gov.uk/government/publications/uk-one-health-report-joint-report-on-antibiotic-use-antibiotic-sales-and-antibiotic-resistance
- Alliance to Save Our Antibiotics, 2024. How to end the misuse of antibiotics in farming, https://saveourantibiotics.org/media/2166/how-to-end-the-misuse-of-antibiotics-in-farming-full.pdf
- Veterinary Medicines Directorate, 2023. UK Veterinary Antibiotic Resistance and Sales Surveillance Report UK-VARSS 2022, https://www.gov.uk/government/publications/veterinary-antimicrobial-resistance-and-sales-surveillance-2022
- European Surveillance of Veterinary Antimicrobial Consumption (ESVAC): 2009 – 2023, https://www.ema.europa.eu/en/veterinary-regulatory-overview/antimicrobial-resistance-veterinary-medicine/european-surveillance-veterinary-antimicrobial-consumption-esvac-2009-2023
- The Veterinary Medicines (Amendment etc.) Regulations 2024, https://www.legislation.gov.uk/uksi/2024/567/contents/made
- Alliance to Save Our Antibiotics, 2024. New regulations on farm antibiotics for Great Britain and how they compare to the regulations in the European Union, https://saveourantibiotics.org/media/2169/new-regulations-on-farm-antibiotics-for-great-britain-and-how-they-compare-to-the-regulations-in-the-european-union.pdf
- European Food Safety Authority, 2023. Welfare of broilers on farm, https://www.efsa.europa.eu/en/efsa-journal/pub/7788
- Netherlands Veterinary Medicines Institute (SDa), https://www.autoriteitdiergeneesmiddelen.nl/en/publications/general-reports
- AHDB, Indoor breeding herd Key Performance Indicators, https://porktools.ahdb.org.uk/prices-stats/costings-herd-performance/indoor-breeding-herd/
- AHDB, Average UK milk yields by calendar year, https://ahdb.org.uk/dairy/uk-milk-yield
- AHDB, UK milk productivity: the global context, https://ahdb.org.uk/news/uk-milk-productivity-the-global-context/
