An Etymological Dictionary of the German Language/Annotated/Farre
Farre, masculine, ‘bullock, bull,’ from the equivalent Middle High German varre, var, masculine, Old High German farro, far, masculine; corresponding to Dutch varre, var, ‘bull,’ Anglo-Saxon fearr, masculine, Old Icelandic farre, masculine, ‘bull.’ Since there is a corresponding fen. form, Färse, the rr must have originated in rz (rs), (compare dürr, irre). —