Animal Study Proposal Guidance for Animal Numbers Justification

Part D of the NCI Animal Study Proposal requires a justification for the numbers of animals to be used. Clearly define the various experimental groups. A table that could be attached to the ASP will simplify the review by the ACUC. In general, animal study proposals can be broken down into four categories when considering animal number justifications. Each category requires a different approach to the justification provision, as suggested below:

• Proposals wherein an experimental design dictates the numbers of animals required. Justification should include numbers and types of groups, numbers of animals per group, number of experiments per year to arrive at a total number of animals necessary to complete the study or for a maximum of three years. When appropriate, it should be demonstrated that the sample size is sufficient to assure reasonable power in significance testing or reasonable precision if the goal is estimation. If this information is included in Part E - Experimental Protocol, a reference to that section would suffice. Factors which may reasonably be expected to impact the numbers of animals in a significant way should also be included to preclude future amendments.
• Proposals wherein the use of animals is merely for the harvesting of normal tissues, organs or fluids for in vitro use. A short statement citing past usage levels per year (per experiment, etc.) necessary to meet the P.I.'s tissue or fluid requirements for each year of the proposal would be sufficient. If no prior experience is available, a statement relating anticipated amounts of material needed and the number of animals expected to provide that amount would be sufficient.
• Proposals wherein animals are used for the production of biologic reagents or cells, i.e. monoclonal or polyclonal antibody production, tumor propagation, etc. A simple explanation (based on experience or anticipated production capability) of how many animals would be necessary to provide a volume or other measure of material necessary for each year of the proposal. This should also be related to the number of antigens, tumors, etc. that would be covered by the proposal.
• Proposals wherein animals are kept for breeding and maintenance purposes and not subject to planned experimental manipulations.Studies involving genetic analysis are often animal-intensive and may involve culling a large number of excess animals.  The ACUC would like the investigator to estimate the number of animals required for maintaining specialized breeding colonies and provide a brief explanation for the numbers if they appear to exceed the guidelines provided below.

The NCI LASP has developed a spreadsheet and a web-based animal number calculator to assist in determining breeding colony size. The output results may be printed and appended to ASPs when appropriate.

The following general guidelines are taken from the Institutional Animal Care and Use Committee Guidebook (2002):

After founder transgenic or knockout mice have been identified, between 80 and 100 mice/year may be needed to maintain and characterize the line.  This assumes 5 breeder pairs per line, breeder replacement, and no unusual fertility or maintenance problems.

Up to 750 mice are required to construct a congenic strain using “speed congenics.” If the homozygous mutant does not breed and intercross matings must be employed, the estimated number rises to 1200.

Up to 1200 mice are required to map a single gene with recessive inheritance and full penetrance and have adequate numbers of progeny for developmental studies, phenotyping, and linkage analysis.

NCI Animal Care and Use Committee - Approved 7/19/91 - Revised 6/26/96 – Revised 10/28/2004

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