Housing breeding mice in three different IVC systems: maternal performance and pup development

Area of Science:

• Laboratory animal science
• Animal welfare
• Comparative physiology

Background:

• Proper housing is crucial for laboratory mice, particularly lactating females and developing pups.
• Individually ventilated cages (IVCs) are standard, but variations in design and ventilation exist.
• Understanding the impact of different IVC environments on mouse welfare and development is essential.

Purpose of the Study:

• To investigate how three distinct individually ventilated cage (IVC) types influence maternal performance and pup development in C57BL/6NCrl and Crl:NMRI Foxn1^nu mice.
• To identify specific cage design elements affecting the in-cage environment and their consequences.
• To determine if different mouse genotypes respond variably to IVC conditions.

Main Methods:

• Comparison of maternal performance (body weight, feed/water consumption) and pup growth across three IVC types.
• Assessment of in-cage climate parameters within each IVC type.
• Evaluation of nest quality as an indicator of animal well-being.
• Utilizing two mouse strains: C57BL/6NCrl and Crl:NMRI Foxn1^nu.

Main Results:

• Significant differences observed in in-cage climate, maternal body weight, pup growth, feed/water intake, and nest quality among the tested IVC types.
• The NMRI NU mouse strain exhibited a more pronounced response to variations in cage environment.
• Cage physical construction, including feed hopper and air inlet/outlet placement, correlated with observed differences.

Conclusions:

• Individually ventilated cage (IVC) in-cage climate demonstrably affects maternal mouse welfare and pup growth.
• Management strategies for IVCs may need to be strain-specific and consider physiological status.
• Cage design features play a critical role in shaping the microenvironment and its impact on laboratory mice.