The MooCall HEAT Collar is worn by nature's best bovine heat detector-the bull himself. As he approaches each cow or heifer that is wearing a MooCall eartag, the collar records such things as cow-bull proximity, mounting behavior, and bull activity to determine the exact time she's in heat, whether she repeats, likely due date, even her fertility over time. These data are then forwarded as text messages to one's cell phone and an alert to his MooCall bed-manager app.