A rack system for mounting a plurality of disposable animal containment cage assemblies, comprising: a disposable animal containment cage assembly comprising a cage base, a thin polymer lid including a flexible surface, a flange, and a first and a second conical receptacle (66, 68, 266, 268) extending outwardly from the lid; a frame (16, 216) comprising shelf assemblies configured to receive and support the disposable animal containment cage assembly; at least one blower (24, 26, 224, 226) coupled to a manifold and plenum system of the frame (16, 216); each of which shelf assemblies is secured to the frame and comprise a first and a second fixed nozzle (70, 72, 270, 272) and having two substantially parallel longitudinal rails on opposite sides of the shelf assembly each having an upper edge configured to receive a bottom surface of the flange portion of the disposable animal containment cage assembly engaged therewith, with each rail being spaced from the first or the second nozzle (70, 72, 270, 272) of the shelf assembly such that the first and second conical receptacles (66, 68, 266, 268) extending outwardly from the lid of the containment cage assembly are biased upward against the respective first or the second fixed nozzle (70, 72, 270, 272) of the shelf assembly due to the resilient flexibility of the thin polymer lid of the cage assembly for establishing a seal between the respective first and second nozzles (70, 72, 270, 272) and conical receptacles (66, 68, 266, 268) for a controllable flow of air therethrough and through a conduit of the shelf assembly which is in communication with an inner passageway of the manifold and plenum system. a disposable animal containment cage assembly comprising a cage base, a thin polymer lid including a flexible surface, a flange, and a first and a second conical receptacle (66, 68, 266, 268) extending outwardly from the lid; a frame (16, 216) comprising shelf assemblies configured to receive and support the disposable animal containment cage assembly; at least one blower (24, 26, 224, 226) coupled to a manifold and plenum system of the frame (16, 216); each of which shelf assemblies is secured to the frame and comprise a first and a second fixed nozzle (70, 72, 270, 272) and having two substantially parallel longitudinal rails on opposite sides of the shelf assembly each having an upper edge configured to receive a bottom surface of the flange portion of the disposable animal containment cage assembly engaged therewith, with each rail being spaced from the first or the second nozzle (70, 72, 270, 272) of the shelf assembly such that the first and second conical receptacles (66, 68, 266, 268) extending outwardly from the lid of the containment cage assembly are biased upward against the respective first or the second fixed nozzle (70, 72, 270, 272) of the shelf assembly due to the resilient flexibility of the thin polymer lid of the cage assembly for establishing a seal between the respective first and second nozzles (70, 72, 270, 272) and conical receptacles (66, 68, 266, 268) for a controllable flow of air therethrough and through a conduit of the shelf assembly which is in communication with an inner passageway of the manifold and plenum system.