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Office-led project

Breeding and colony management

White icons of three mice on a blue background. Two female mice on the left hand side are each crossed with the same male mouse on the right side, indicating how different mice can be paired for optimised breeding.

At a glance

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  • Reduction
  • Refinement


The use of genetically altered animals has become a mainstay of biomedical research, with new technical approaches (e.g. CRISPR/Cas9) to manipulate the expression of genetic components evolving rapidly. Generating a genetically altered strain of mice uses large numbers of animals to create a colony, and to maintain a colony from which experimental animals are produced. Following best practices for colony management can help minimise the number of surplus animals used in breeding colonies, as well as controlling the genetic characteristics of the colony, leading to more reliable experimental results. 

Returning to breeding mice following the COVID-19 lockdown presents many challenges but also an opportunity to apply best practices to colony management. In response, we have convened an expert working group to generate best practice guidance for breeding and colony management, in light of the scenarios facing research and technical staff re-starting breeding and experiments following interruption due to lockdown. 

The working group includes experts in breeding, archiving, colony management and experimental design from academic and commercial organisations. The group has combined their knowledge of colony management and experimental design to define current best practices in key areas, including best practice for archiving strains, breeding strategies to avoid genetic drift and using intermittent breeding strategies as an alternative to constant mating to reduce animal use. These best practice concepts were then included in the development of strategies and advice for common scenarios when returning to breeding and research following a pause or interruption (e.g. an experiment was only partially completed prior to lockdown and now animals are required to complete the remaining part of the experiment).  

The aim is that this guidance will support researchers and technical staff involved in breeding mice to follow best practice in colony management, when returning to research and continuing into the future. 

Visit our breeding and colony management resource page for best practice guidance for optimising the use of animals and avoiding wastage, using principles that apply to multiple species.

Working group members

Name Affiliation
Prof Ian Jackson (Chair)  MRC Human Genetics Unit, University of Edinburgh 
Dr Simon Bate  GSK 
Mr James Bussell  University of Oxford 
Ms Caroline Chadwick  University of Birmingham 
Mr Brendan Doe  CRUK Cambridge Institute 
Dr Ellen Forty  The NC3Rs 
Ms Sarah Hart-Johnson  Francis Crick Institute 
Prof Monica Justice  The Centre for Phenogenomics/ University of Toronto 
Dr Natalia Moncaut  CRUK Manchester Institute  
Dr Peter Oliver  MRC Harwell 
Dr Esther Pearl   The NC3Rs 
Dr Michelle Stewart  Mary Lyon Centre (MRC Harwell) 
Dr Sara Wells  Mary Lyon Centre (MRC Harwell) 
Dr Jacqui White  The Jackson Laboratory