Guidelines for the Care and Use of Mammals in Neuroscience and Behavioral Research (2003) / Chapter Skim
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Appendix B: Estimating Animal Numbers
Appendix B: Estimating Animal Numbers
Pages 181-190
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From page 181... ...
For example, a breeding colony may be required for an established animal model because the animal model is not commercially available, young animals with specific age or weight that cannot be provided by a commercial breeding colony are required, or the physiologic status of a mutant animal is too severely affected for it to survive shipment. Investigators developing a new spontaneous or induced mutant animal model need to maintain their own breeding colony because there is no alternative source for the mutant.
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From page 182... ...
If suckling animals will be euthanized at or before weaning because they are of the wrong genotype or sex for the experiment, they should be included as animals held but not subject to experimental manipulation. One alternative is to instruct investigators to include all preweaning animals subjected to experimental manipulation in the estimated number of animals or for the IACUC to request estimated animal numbers as follows: Estimated number of weaned and adult animals to be subjected to experimental manipulation Estimated number of suckling animals to be subjected to experimental manipulation TOTAL Estimated number of breeders held but not subjected to experimental manipulation Estimated number of suckling animals to be euthanized at or before weaning and not subjected to experimental manipulation *
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From page 183... ...
( 1 ) Number female breeders = Number animals required for experiment x infertility factor Average pups weaned per litter x sex correction x mutant correction a)
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From page 184... ...
Depending on the strain of mice, the number of pups weaned by females in pair matings may exceed the number of pups weaned by females in trio or harem matings. In addition to the desired 50 homozygous mutant female mice, the 84 breeders will produce on the average 50 homozygous mutant male mice, 200 heterozygous mice of both sexes, and 100 homozygous wild-type mice of both sexes.
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From page 185... ...
The number of pups weaned per female per week is determined as follows: Number of pups weaned weeks 1 Wean per female per weed X Number of female breeders n week Once the number of pups weaned per female per week is determined, the number of female breeders is estimated as follows: Number of _ number of animals per week female breeder~wean per female sex X mutant: ~ per week correction correction Example: Fifty homozygous mutant female mice are required once a month with a 2-week age range. Homozygous mutant mice are fully viable but sterile.
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From page 186... ...
1,200 mice can be 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. That number assumes a breeding colony of 10-12 pair matings with a 6- to 8-month reproductive life span, around 90% productive matings, replacement of breeders, and no unusual mutant infertility or mortality.
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From page 187... ...
A naturally ovulating hybrid or outbred female mouse will usually yield more fertilized eggs or embryos. Immature female mice given hormones to induce ovulation ovulate larger numbers of eggs 16-24 eggs per inbred female (Mobraaten, 1981)
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From page 188... ...
As with collection of fertilized eggs, additional females must be mated to the vasectomized males to compensate for females that do not mate at the appropriate time. Not all surgically transferred microinjected two-cell embryos or blastocysts undergo further cell division, implantation in the uterus, or development into viable liveborn pups.
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From page 189... ...
Number of animals Donor females to produce desired number of naturally ovulated fertilized eggs (or blastocysts)
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From page 190... ...
Estimate as follows: total number of viable embryos (number of embryos transferred by pseudopregnant females: ~ a pseudopregnant female with vasectomized malesJ number of viable embryos = number of blastocysts injected x expected % of blastocysts viable after injection (iv) N equals estimated ratio of nontransgenic to transgenic animals to be weaned from original number of blastocysts.
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