A portable and collapsible modular calf housing system featuring at least one pen comprising a front panel and two side panels and optionally a rear panel forming a pen. The side panels include channels in which the front panel can slide vertically to adjust the height of a feeding pail attached thereto. The channels are disposed on either face of each side panel to enable a front panel from each one of adjacent pens to be joined to form a plurality of interconnected pens.
