From the MN DNR website

POSSESSION OF BIG GAME
Any person who takes a big game animal must retain the license, site tag,permit and possession(registration) tag for as long as any part of the meat is in possession.

It dosn't specificaly state anything about antlers.

http://files.dnr.state.mn.us/rlp/reg...ng/biggame.pdf
Page 55 of the document.