An animal holding pen comprises front, rear, left and right rigid plastic panels that interlock to one another by means of a coupling system including stainless steel fasteners that remain physically attached to the side panel assemblies when the front and rear panels are detached. The front panel may include an opening through which the animal may extend its head when feeding. Feed and water are adapted to be contained in pails held by a pail support assembly that can be folded up against the front panel or deployed perpendicular to the front panel.