In accordance with the invention a method for detecting oestrus behaviour of a milking animal is provided. The milking animal is provided with a sensor means for detecting an activity level of the milking animal. The method (10) comprises the steps of: monitoring an activity level increase of the milking animal by the sensor means； and detecting the oestrus behaviour in dependence on a set threshold activity level increase, wherein the threshold activity level increase is set to be indicative of an oestrus behaviour of the milking animal in dependence on time of day. The invention provides a reliable means for determining when a milking animal is in heat.
