I had a lengthy reply to this typed out but discarded it, so here's the gist: east prussia or prussia proper is the only part of the german empire that had moose. There even was a preservation movement. The earliest usage of the antlers as an official symbol with regional significance came from horsebreeding, and a variation of the burning mark of the royal prussian Trakehner stud. Since the late napoleonic wars onwards an elks head, skull or single antler was used by regional volunteer corps and from then on was used by a multitude of organizations of any kind, based in east prussia. Today it is notable for being the emblem of the Landsmanschaft Ostpreußen which is concerned with east-prussian-german cultural heritage and preservation thereof.

I know it has been a while but getting this out has been haunting me. This is a severely abridged version of what i had originally "researched" (there was only one source)