If Wisconsinâ??s essence were distilled to one four-note riff, it would be this: D, C-sharp, E, D. Whether played on trumpets or pianos, sung by sopranos or tenors, thumped from synthesizers or shouted by rappers, those four musical notes are encoded into Wisconsinâ??s DNA. The notes, as well as the rest of the ditty that would become not just the Badger fight song but Wisconsinâ??s state song, were first performed 100 years ago Tuesday when a glee club warbled “On, Wisconsin!” for the first time in practice followed by the first known public performance at a pep rally the next day.