Before Linus The Lionhearted roared onto the screen in 1964, General Foods (now part of Kraft) sponsored The Bugs Bunny Show on ABC. This enabled Warner Bros. to produce a series of commercials to promote Post Cereals and Tang, a popular instant breakfast drink better known for its association with NASA and the Apollo space program. Imbaaack uploaded the following block of ads, bracketed by a commercial promoting The Bugs Bunny Show and a couple of Post-centric bumpers from the same show. The ads were produced between 1960-4, before independent producer Ed Graham landed the license to adapt Post's own mascots for television.
I believe it's either Mel Blanc or Hal Smith (The Andy Griffith Show) as Elmer Fudd, by the way.