IVC - Ten Years of Experience with Building-Integrated Ventilated Caging Systems: What We’ve Learned

In 2003 the University of Michigan opened the first of its two large vivaria that were engineered to have rodent racks ventilated directly by the building's air supply and exhaust systems. The overall outcome of this effort has been extremely successful: cages are ventilated steadily by filtered air, the rooms are quieter and more pleasant work places, and rodent breeding has been successful in colonies in which previous rackmounted blowers negatively affected the birth/weaning rates. Use of the building ventilation system has benefitted the animal care staff ergonomically by eliminating the need to move blowers off/on the racks on change days, and has eliminated the labor associated with cleaning the blower pre-filters. It has also been subjectively noted that cages integrated with the building ventilation system need fewer "as-needed" changes prior to the regularly scheduled change days. Another positive outcome of the integrated system has been a closer working relationship between building maintenance staff and the animal facility managers. Our systems were designed with separate thermostats for room air and intra-cage air, in an effort to control cage temperature independently from room temperature (i.e., warmer cages for mice with cooler rooms for staff). Unfortunately this goal was not achieved, as the temperature of the air provided to the cages was readily influenced by the temperature in the room. A review of our study on the effects of differing thermostatic setpoints, including measurement of air temperatures at multiple locations within the rack supply plena, will be presented.