What movie series was a spin-off of the 1947 movie, The Egg and I?

Ma and Pa Kettle are comic film characters of the successful film series of the same name, produced by Universal Studios, in the late 1940s and 1950s. They are a hillbilly couple with fifteen children whose lives turn upside-down when they win a model-home-of-the-future in a slogan-writing contest. At the verge of getting their farm condemned, the Kettles move into the prize home that is different from their country lifestyle. After that, they are subjected to more unusual situations.

Originally based on real-life farming neighbors in Washington state, United States, Ma and Pa Kettle were created by Betty MacDonald in whose 1945 best-selling novel, The Egg and I, they appeared. The success of the novel spawned the 1947 film The Egg and I starring Claudette Colbert and Fred MacMurray, also co-starring Marjorie Main and Percy Kilbride as Ma and Pa Kettle. Main was nominated for an Academy Award for Best Supporting Actress for her role.

After the audiences' positive reaction to the Kettles in the film, Universal Studios produced nine more films, with Marjorie Main reprising her role in all and Percy Kilbride reprising his in seven. The films grossed an estimated $35 million altogether at the box office and are said to have saved Universal from bankruptcy.