Pfizer-(Progesterone) Cattle breeding is more successful with this new progesterone insert. It improves timing and efficiency of beef cow and heifer breeding programs when using Lutalyse. The CIDR insert provides precise control of the estrous cycle and ovulation. For: artificial insemination, easier estrous detection, planned natural breeding, embryo collection and transfer programs, and treating anestrus. Administer inserts intravaginally, one per animal in beef cows and heifers. The CIDR insert releases progesterone during a seven day treatment period. To assure satisfactory synchronization an injection of Lutalyse RX must be given to all cattle one day before insert removal. Removal of the insert on treatment day seven results in a drop in plasma progesterone, triggering estrus within three days Lutalyse Rx is a prescription drug.