On Feb 18, 1930, Elm Farm Ollie became the first cow to fly in an
airplane.  During the flight, which ws attended by reporters, she was
milked and the milk was sealed in paper containers and parachuted over St.
Louis, MO.  This date is celebrated in Wisconsin as Elm Farm Ollie Day,
during which residents of the "Dairy State" mark this festive event by
consuming large amounts of cheese and ice cream and by singing the _Bovine
Cantata_ from Moocini's lyric opera _Madame Butterfat_.
  
-- from Chase's Annual Events