In an automatic milking installation including a robot arm (2) with a gripper (3) for attaching teat cups (4) to the teats of an animal, e.g. a cow, to be milked, for applying a teat dip to the teats after milking different members, such as spray nozzles (5a, 5b), dipping cups (5c, 5d) and sponge or cloth rollers (5e), are provided for applying different teat dip compositions. Under the control of a computer, the robot arm collects the member (5) appropriate for supplying the selected composition and takes it to a position appropriate for application of that composition. The selection can e effected in dependence upon the teat skin condition, e.g. detected by a camera (15) and/or environmental conditions.