A livestock pen with ends and long sides for permanently restricting the freedom of movement of animals kept therein. The livestock pen contains a moving, endless belt that supports all the weight of the animals. The belt is arranged to move from an inlet end towards an outlet end. An outlet end panel forms a gap between the belt and the outlet end panel's lowermost transverse member. At the belt's outlet end, a sensing means, when actuated, stops any ongoing belt movement. An additional aspect relates to a method for stopping the movement of an endless belt in a livestock pen, whereby a sensing means registers when a part of an animal is in a restricted area of the livestock pen. A signal from the sensing means then stops the belt's drive mechanism.