A detection tag is disclosed for the detection of the reproductive status of animals, the detection tag comprising: a first surface affixable to the hide of an animal a second and opposite surface including abradable material and first and second electronic signal transmission means configured to transmit first and second electronic signals having detectably different characteristics the detection tag being configured such that removal of some or all of the abradable material alters the ability of the detection tag to transmit the first signal or alters a characteristic of the first signal.
