Methods which minimise the number of animals used per experiment

This aim considers whether an appropriate number and species of animals have been selected for a particular experiment. Using too many animals must be avoided whilst using too few may result in an inconclusive result, necessitating wasteful repetition. Reducing the number of animals required involves careful experimental planning and good statistical analysis of data, including, for example, the use of pilot studies.

When calculating animal usage in experiments, it is important to take into account any animals which may have been produced but not used. This includes any additional animals that are inevitably generated when breeding experimental animals but cannot themselves be used in experiments because of their gender or genetic makeup. Minimising sources of variability such as genetic diversity, gender and age can reduce the number needed to generate clear data, although it is also essential to ask whether results obtained in this way have wider relevance, especially to the diverse human population.

As well as ensuring careful experimental planning, Reduction should also be an active process to look at ways in which established experimental designs can be improved with no loss of information quality.


Examples of Reduction

  • Computational modelling of molecular and cellular processes allows to us to reduce the numbers of animals used in research. This includes both making initial discoveries ‘in silico’ and thereby reducing the involvement of animals in research until results need to be validated in a living system, and replacing the use of animals entirely. One example of the former is the study of calcium signalling in learning and memory (research publication).
  • Computerised record keeping and reporting tools are used to refine and reduce animal use by monitoring colony size and matching breeding performance to usage. Low usage colonies are cryopreserved as embryos rather than maintaining live animals.
  • An in vitro method using brain explants has been developed to study the early stages of Alzheimer’s disease. This model also establishes a new system for drug testing which could reduce the numbers of mice required for this research.
  • We promote opportunities for tissue sharing. The Institute is a major contributor to an archive of tissues from aged mice established by SHARM (Shared Ageing Research Models).
  • Using the latest research technologies, for example, multi-parameter flow cytometry, allows more data to be gained from fewer cells, thereby reducing the number of donor animals required.