Abstract: The present invention has objectives of providing a low-cost, easy-to-handle individual isolation animal breeding unit and a system for using the same, significantly reducing costs of facilities and maintenance for animal experiments and saving on labor, and providing a new animal transportation form. For achieving the objectives, the present invention provides a system for maintaining an animal breeding environment, comprising A) an animal breeding unit capable of comprising an internal tray having a sufficient space for breeding an animal of interest, comprising an external tray capable of accommodating the internal tray, and capable of keeping a predetermined cleanliness degree; B) a method for providing the internal tray having the predetermined cleanliness degree; C) an internal tray exchange unit capable of accommodating the animal breeding unit and exchanging the internal tray while keeping the predetermined cleanliness degree; and D) a method for recovering the exchanged internal tray.

Abstract: The present invention has objectives of providing a low-cost, easy-to-handle individual isolation animal breeding unit and a system for using the same, significantly reducing costs of facilities and maintenance for animal experiments and saving on labor, and providing a new animal transportation form (breeding cage having a transportation function).