Microclimate in two types of rat cages

Area of Science:

• Laboratory animal science
• Environmental monitoring

Background:

• Rodent housing conditions significantly impact animal welfare and research outcomes.
• Microclimate parameters like temperature, humidity, and ammonia are critical for laboratory animal husbandry.
• Different cage materials and designs may influence the microenvironment within animal housing.

Purpose of the Study:

• To compare the microclimate, specifically temperature, relative humidity, and ammonia concentration, in two distinct types of rat cages.
• To evaluate the ammonia build-up dynamics in solid-floor Makrolon cages versus wire-mesh stainless steel cages.
• To determine if ammonia levels in either cage type exceed established safety thresholds for laboratory animals and human handlers.

Main Methods:

• Two cage types (Makrolon IV solid floor, stainless steel wire mesh) housing five rats each were used.
• Microclimate parameters (temperature, relative humidity, ammonia concentration) were measured twice daily for 8 days.
• Cage cleaning occurred every 4 days to assess ammonia accumulation over time.

Main Results:

• Ammonia concentration showed the most significant difference between cage types.
• Makrolon cages consistently maintained ammonia levels below 5 ppm.
• Stainless steel cages exhibited a continuous increase in ammonia, exceeding the human threshold (25 ppm) by day three after cleaning.

Conclusions:

• Solid-floor Makrolon cages provide a superior microenvironment with significantly lower ammonia concentrations compared to wire-mesh stainless steel cages.
• Wire-mesh stainless steel cages pose a risk due to rapid ammonia build-up, potentially impacting animal health and research integrity.
• Cage design is a critical factor in managing airborne contaminants in laboratory animal housing.