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Updated: May 12, 2026
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Determination of Reproductive Competence by Confirming Pubertal Onset and Performing a Fertility Assay in Mice and Rats
Published on: October 13, 2018
Comparison of 2 rat breeding schemes using conventional caging
Kenneth P Allen1, Melinda R Dwinell, Allison Zappa
1Biomedical Resource Center, Office of Research, Medical College of Wisconsin, Milwaukee, WI, USA. kpallen@mcw.edu
Summary
Continuous housing of rat pairs in conventional cages resulted in higher pup weaning weights compared to intermittent housing. This suggests a preferable breeding strategy for laboratory animal care.
Area of Science:
- Laboratory animal science
- Animal welfare
- Comparative biology
Background:
- The 8th edition of the Guide for the Care and Use of Laboratory Animals recommends increased cage floor space for female rats with litters.
- Conventional rat cages may not meet these updated space recommendations for housing breeding pairs with litters.
Purpose of the Study:
- To evaluate two breeding schemes for rats within conventional cage limitations.
- To compare continuous versus intermittent housing of monogamous rat pairs.
Main Methods:
- Two breeding schemes were assessed: continuous cohabitation of monogamous pairs and intermittent housing with male removal post-parturition.
- Both schemes utilized traditional cages providing 140 in.² (903 cm²) of floor space.
Main Results:
- No significant differences were observed in generation time, litters per pair, weaning success, or pups born/weaned between the two schemes.
- However, pups from the continuously housed pairs (Scheme 1) exhibited significantly higher average weaning weights.
Conclusions:
- Continuous housing of monogamous rat pairs may be a more effective strategy than intermittent housing when using conventional cages.
- This approach can lead to improved pup growth, supporting updated animal care guidelines.
