I may be wrong but I believe the estrous cycle is related to photoperiodism. The Pineal gland in the brain controls it and it is related to the lenght of daylight. That is why the rut always close to the same dates. I believe the captive does are kept in pens where the handlers control the daylight so they can induce estrous. I used to have a lot of success with doe pee but the last ten years I have not even brought in one buck with it...........dabow