ZINCLESS
ZINCLESS
A BBSRC-funded project​​​
Welcome to the ZINCLESS research project
We aim to advance knowledge and drive collaboration to explore how zinc oxide removal from pig diet affects gut health, antimicrobial resistance, and the microbiome.
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The support of all participating producers in this study is gratefully acknowledged, alongside the hard work and dedication of the sampling teams.

Image credit: SRUC
Image credit: SRUC
Zinc oxide withdrawal
Young pigs may face health problems when they are weaned, including post-weaning diarrhoea (PWD). This condition causes illness, distress and weight loss, with severe cases even leading to death. PWD is mainly caused by enterotoxigenic Escherichia coli (E. coli) bacteria, but other factors including secondary infections and the stress of weaning make piglets more susceptible. PWD is a major animal health and welfare concern and prevention and control of this condition is a priority for producers.
Before June 2024, farmers had the option of adding prophylactic levels of zinc oxide (ZnO) to weaner piglet feed to help prevent PWD. While using ZnO supported gut health and lowered the risk of disease, it also had some disadvantages. Of particular concern, ZnO is thought to encourage bacteria to develop resistance to antibiotics, contributing to the growing problem of antimicrobial resistance (AMR). There are also concerns that spreading pig manure to land risks contamination of soils over time with zinc, a heavy metal.​
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Image credit: SRUC
Due to the concerns linking ZnO with AMR and environmental pollution, the European Medicines Agency ruled in 2017 that the risks of pharmacological ZnO supplementation in the pig industry outweighed the benefits and banned supplementation above 150 ppm in weaner diet in the EU from mid-2022, with UK regulatory withdrawal implemented from June 2024.
Project rationale and aims

Image credit: SRUC
​The aim of our project is to examine the consequences of the UK regulatory withdrawal of ZnO from weaner diet on PWD, antimicrobial resistance and the gut microbiome in weaning pigs.
We are a multi-disciplinary research team from across the UK, working closely with participating industry, producers, and clinicians. ZINCLESS* began in March 2024 and is very timely, with the project running for the first three years following regulatory withdrawal of ZnO in the UK.
We are delivering this research through four inter-connected work packages, aligned to our four project aims:​
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Evaluate the impact of ZnO removal from weaner pig diet on PWD, pathogens and AMR over the first 12 months following withdrawal.
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Identify potentially beneficial bacteria by exploring differences in the gut flora of weaner pigs in the presence and absence of ZnO.
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Understand how the elimination of ZnO may affect ETEC strain diversity and AMR in gut bacteria through the use of genome sequencing technology.
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Engage in two-way knowledge exchange with producers, their veterinarians, and industry stakeholders.
Our findings will contribute to an improved understanding of the consequences of withdrawing ZnO, and help inform the development of alternatives to improve gut health. Read about the impacts of our project.
Project overview
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*BBSRC project title: Intended and Unintended Consequences of the ZnO Ban From Pig Diets on Antimicrobial Resistance, Post Weaning Diarrhoea, and the Microbiome​​