Reduce: reduction of animal numbers in research

Reduction is one of the "three Rs" (Replacement, Reduction and Replacement) of Russell and Burch, a concept which is described in more detail here.

They defined the three Rs as:

Replacement alternatives: methods which permit a given purpose to be achieved without conducting experiments or other scientific procedures on animals

Reduction alternatives: methods for obtaining comparable levels of information from the use of fewer animals in scientific procedures, or for obtaining more information from the same number of animals

Refinement alternatives: methods which alleviate or minimise potential pain, suffering or distress, and which enhance animal well-being

Reduction is often achievable by better experimental design and statistical analysis.

The PREPARE guidelines contain links to many resources which can be used to implement the 3Rs.

The Rawle Report (2023), commissioned by the NC3Rs, concluded that, in the UK:

'Both AWERBs and funders report paying closer attention to experimental design and statistics in their reviews over recent years, although AWERBs report a shortage of people with the necessary expertise
to review this area. The funders’ aim is to ensure the research they are funding is robust and reproducible, which should lead to reductions in overall animal use, although paradoxically the review of experimental
design often indicates that more animals are required for each experiment to achieve sufficient statistical power.

It is not possible to review the design of every experiment covered by a grant or a PPL application covering three to five years at the outset, and both PPL and grant reviews focus on typical or early experiments. ASRU reviews the basic principles of experimental design but does not undertake a detailed assessment of the proposed statistical methods.

Neither AWERBs nor funders reported much discussion in their reviews of the potential to use methodological advances such as in-cage monitoring, microsampling, or use of imaging techniques to enable more information to be obtained from fewer animals.'

Other literature

• Richter SH (2024): Challenging current scientific practice: how a shift in research methodology could reduce animal use
• de Boo & Hendriksen C (2005): Reduction Strategies in Animal Research: A Review of Scientific Approaches at the Intra-experimental, Supra-experimental and Extra-experimental Levels