Assembly comprising a passageway for livestock, the passageway being delimited by side delimitations, for passage of the livestock from a first space to a second space. The assembly comprises a gate system mounted in the passageway, the gate system comprising at least one self-closing gate leaf which is movable between a closed position and one or more open positions which include a pass position wherein passage to the second space is possible for an animal from the livestock, and wherein the gate leaf is moveable to an open position by pressure exerted by an animal from the livestock for passing through the passageway to the second space. The assembly also comprises a device for determining an ID of an animal from the livestock, and a device for blocking the gate leaf from moving to the pass position, wherein the blocking device can be activated to a blocking position in response to data from the ID determining device.
