Heat Detection. Signs. of heat. No sign. of heat. No. Yes. Yes. Begin. Pick up heat detection card from office.. Slowly approach . Pen 2 from the south end of the barn.. Quietly watch group . for signs of heat.. Is cow standing . to be mounted?. Fill out heat card:. * Record ear tag #,. * Circle sign of heat. Is cow showing 2 or . more secondary signs:. * Mounting others. * Mucus discharge. * Swelling vulva. * Bellowing/restless. * Rubbed tailhead hair. Continue watching for at least 30 minutes. After 30 minutes, return card to office and place in heat card box.. End. Complete date, time, and observer name.. Heat Detection Flowchart. February 24, 2007.