Deer (and other animals such as elk)
shed their antlers every year and then grow a complete new "rack". This shedding procedure takes two or three weeks to complete, while the regeneration takes the entire summer to conclude - and the cycle begins again. With the sole exception of reindeer (both male and female), male deer shed their antlers between January and April after the mating season. By then, antlers are no longer necessary to attract females, or challenge other male competitors.
(info via; antler-shed.com)
