Unfortunately, I don't think that's correct. Before deer antlers get hard, they are a live appendage and cause considerable pain when lopped off. Check out this exerpt from
here:
<blockquote>Antlers are defined as the appendages which grow annually from the pedicle formation of the frontal bone of deer. They are therefore quite unlike the horns of cattle, sheep and goats, which do not regrow if removed correctly. Antlers also develop and mature in a manner different to horns and broadly two stages of antler development are recognised: velvet antler and hard antler.
Velvet antler is defined as growing antler which contains an abundant blood and nerve supply and which has a fully intact skin with a covering of fine soft hair. The surgical removal of velvet antler without some form of anaesthesia will cause pain and distress to the animal.
Hard antler is the antler when growth has ceased, calcification has occurred, and the skin,nerve and blood supply are no longer functional. This is when the antler has no live skin at its base. Hard antler can be removed above the pedicle without causing any pain or bleeding. Hard antlers are shed naturally just before new velvet antlers begin to develop from the pedicle.</blockquote>