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