EVAL-FARMS: Evaluating the Threat of Antimicrobial Resistance in Agricultural Manures and Slurries

Antibiotics are used extensively to fight bacterial infections and have saved millions of lives. However, the bacteria are becoming resistant to antibiotics and some antibiotics have stopped working. We refer to this as antimicrobial resistance - AMR. We don't just use antibiotics for people; similar amounts are given to farm animals. More than 900 million farm animals are reared every year in the UK and antibiotic treatments are vital for their welfare, for farms as businesses, and for us to enjoy affordable food. However, farms may be contributing to the development of AMR. The aim of this project is to improve our understanding of how farm practice, especially the way in which manure is handled, could lead to AMR in animal and human pathogens. This understanding will help farmers and vets find new ways to reduce AMR, without harming their animals or their businesses.

For research purposes, Nottingham University maintains a typical high performance dairy farm - its 200 cows produce a lot of milk and a lot of manure. The waste is stored in a 3 million litre slurry tank, any excess goes into a 7 million litre lagoon. This slurry is applied to fields as organic fertilizer. Cow manure contains many harmless bacteria but some, e.g. E. coli O157, can cause severe infection in people. When cows get sick they are treated with antibiotics. Udder infections are treated by injection of antibiotics into the udder. Since this milk contains antibiotics, it cannot be sold but is discarded into the slurry. Foot infections are treated with an antibacterial footbath, which is also emptied into the slurry tank.

As a result, slurry tanks contain a mixture of bacteria, antibiotics and other antimicrobials that are stored for many months. The bacteria that survive in the presence of antibiotics are more likely to have antibiotic resistance. This resistance is encoded in their genes so passed to the next generation. Worse still, the genes can be passed on to other bacteria in the slurry.

Before we wrote this proposal, we investigated our own farm's slurry tank to see if this might be happening. We tested 160 E. coli strains from the slurry; most carried antibiotic resistance. We also found antibiotics in the tank - including some that bacteria were resistant to. Our mathematical modellers showed that reducing spread of resistance genes in the tank might be more effective in preventing resistance than cutting the use of antibiotics. Conversations with the farm vets revealed that they knew about AMR and had changed some of their antibiotic prescriptions. But these analyses leave us with more questions than answers.

In this project, we want to find out if current farming methods are contributing to the development of harmful antibiotic-resistant bacteria in slurry, bacteria that may then be encountered by humans and animals. To do this, we need to integrate scientific and cultural approaches:

- What bacteria are in the slurry? How many are harmful? What resistance genes do they carry? How do these genes spread?
- How long do antibiotics remain in the tank? Do they degrade?
- What happens to the bacteria and antibiotics after they are spread on fields?
- How do farmers, vets and scientists interpret evidence about AMR? What are their hidden assumptions? Can we improve collaborative decision making on AMR risk management?
- Can we reduce resistance by avoiding mixing together bacteria and antimicrobials in slurry?
- Can we predict the risk of emergence of and exposure to resistant pathogens? Can we predict which interventions are likely to be most effective to reduce AMR, taking into account both human and scientific factors?

Through this research, we will learn what can realistically be done to reduce this risk; not just on this farm, but UK wide. We will work with farmers, vets and policy makers to ensure that our results will make a difference to reducing the risk of harmful AMR bacteria arising in agriculture.

Antibiotics save millions of lives. However, because bacteria adapt, some antibiotics may stop working. We call this antimicrobial resistance - AMR. Farm animals are given antibiotics as well as humans; we need to understand how manure handling on dairy farms could lead to AMR. EVAL-FARMS will help farmers and vets find ways to reduce AMR without harming their animals or businesses, and policy makers to understand AMR risk in agriculture.

Our impact goals are to produce measurable changes in:

- policy understanding of the role slurry handling and management plays in AMR
- the understanding and practice of dairy farmers and associated industries in relation to AMR and slurry management
- wider awareness of the role AMR plays in human food from 'farm-to-fork'.

Who will benefit from this research?

We have identified two key beneficiary communities:

- policy makers working in the fields of waste management, agriculture and the environment in the UK and the EU
- dairy farmers and related industries e.g. vets, farm services and the waste management industry

We will also work to improve public awareness through the media.

How will stakeholders benefit from this research?

1. Policy makers: Our policy stakeholders will benefit from our research in three ways. First, through Defra representatives on our EAB, we will improve the quality of understanding of AMR in the policy community, and take up opportunities to directly influence policy-making. Second, we will produce a policy pack to ensure our evidence is embedded at the leading edge of policy thinking in the UK/EU. The research will be presented in usable formats, including policy/ministerial briefings, case studies and slides. Finally, we will work with the James Hutton Institute to inform Scottish Government policy through the co-creation of research outputs.

2. Dairy farmers and associated industries: We will work with a range of partners (NFU, Severn Trent Water, the BCVA and Velcourt Farm Management Services) to share our findings with the farming community. We will have a presence at events in the dairy diary, in periodicals and will run farm demonstrations to explore the implications of our findings. Co-creation and representing a meaningful understanding of the cultural context will make our research accessible and usable. As a result the dairy industry will improve AMR risk management.

3. Public interest: The UoN Press Office will produce a range of PR material for national and international media outlets including broadcast, print and online platforms covering science, environment and agriculture. The team will have access to UoN's media hub. Articles will be produced for sites such as The Conversation, and messages targeted at programmes such as The Archers and Countryfile.

How will we measure impact?

We will measure the reach and significance of our impact using the following metrics:

- EVAL-FARMS research cited in UK/EU policy documentation, conversation and directives. This will be tracked via policy presence on the EAB and document scanning.
- 90% of policy makers working on slurry management/storage understand the importance of AMR to their work.
- Industrial partners report quantifiable changes in design/practices following access to the research. We will track this via follow up phone calls six months after engagement with the project.
- Numbers of vets taking up our CPD offer or farm visits, and reporting changes in practice via evaluation forms.
- Numbers of dairy farmers accessing our research through periodicals, events and call to action pack downloads.
- Numbers of dairy farmers reporting a change in practice on farms, tracked via the Farm Business Survey using telephone and text messages.
- Media impact metrics are those gathered as a matter of routine by UoN and include reach, value, positive/ negative coverage, media type, source (international and national), press release impact.