It costs a lot of money to seduce someone in my village

The shakeup deals a major blow to The Richards Group, which introduced the Chick-fil-A cows on a billboard with the "Eat Mor Chikin" tagline in 1995. The campaign more than doubled Chick-fil-A's same-store sales and helped turn the regional chicken joint into the one of the largest U.S. restaurant chains with more than $6 billion in sales in 2015 and over 2,000 locations in 43 states and in Washington, D.C.

Stan Richards, the principal and founder of The Richards Group, said in an emailed statement that the agency is sad that the relationship is over, but they are proud of what they have accomplished, especially with the cow campaign.

"The cows are core to the brand's success and certainly we are protective of them -- we think we know them pretty well having given birth to and nurtured their unique personalities for more than two decades," he said. "We hope the cows live on and continue to thrive with a new family."

After Chick-fil-A's chief marketing officer retired and it replaced a vice president, the agency suspected "things would go in a different direction," Richards said.

"We believe that brand is a promise," Richards said. "It's not a logo, a founder, a CMO, or an ad agency. It should be bigger than all of that. This is a brand we love. And have loved for a very long time. We will continue to love it long after its stewardship has left this building."