Reduced performance may result from the failure to confirm pregnancy in dairy cows. The earlier after service that pregnancy can be reliably detected the more useful the method of detection is. Both milk progesterone and veterinary rectal palpation are useful for very early and mid pregnancy confirmation respectively but both have limitations. The BOVEQ (FarmKey Ltd.) detects pregnancy using ultrasonics. Ultrasound waves have the property of travelling through liquids and solids but not air (or any other gas). When they meet an interface between different materials (e.g. fat/muscle, muscle/bone or a pregnant uterus and its contents) thry produce an echo, the strength of which is dependant on how much difference there is at the interface. The uterus of a pregnant animal changes in “tone” and fluid content shortly after breeding and this change is characterised by a specific pattern of ultrasound echoes.