Abstract: Objective To study the micro-environment indicators inside the IVC raising with mice or rats, providing the basic data for enact national IVC standard. Methods The temperature, relative humidity, and ammonia concentration were detected inside the cages raising with mice or rats, and the relations between the ventilation rates and temperature, relative humidity, and ammonia concentration inside the cages were analyzed. Results For the mouse cages, the temperatures were 1.5~2.2℃ higher and the relative humidity was 10%~15% higher inside the cages than those of outside the cages after changing bedding ; while the ammonia concentrations raised gradually the day after day and higher than national standard on the third day after changing bedding. For the rat cages, at rate of 20 times per hour ventilation, the temperature and relative humidity inside the cages raised gradually the day after day, 3℃ and 20% higher than those outside the cages respectively at the third day after changing bedding. The ammonia concentration inside the rat cage was significantly higher than the national standard at the third day after changing bedding. Increasing the ventilation rate can slightly lower the temperature and relative humidity and significantly decrease ammonia concentration inside the cages. Conclusion The temperature, relative humidity, and ammonia concentration inside the IVC cages are apt to be influenced by the animal numbers, animal body sizes, and bedding-change interval, thus affecting the results of animal experiments. In order to decrease the ammonia concentration inside the cages, the ventilation rate of rat IVC cage should be more than 60 per hour. In order to ensure the health and safety of animals raising inside the IVC cages, it is necessary to monitor the ammonia concentration inside the cage periodically.

Key words: Individually Ventilated Cages(IVC), Micro-environment inside cages, Temperature, Relative humidity, Ammonia concentration.