Simple in its design, the Calan Door is the workhorse of the system. The Calan Door has an ergonomic design that promotes easy animal acceptance. Once unlocked, the angled door provides unobstructed access for the animal, promoting relaxed and natural feeding alongside pen mates. When the animal withdraws from the feed trough, the spring-loaded door automatically closes and locks. However, the animal can immediately revisit the feed trough as many times and for as long as it wishes. There is no “lock out”. The Calan door contains a circuit board that controls the electronic functions of the door and lock. The door is lightweight but will withstand the toughest environmental conditions for many years.