There are numerous dairies, all of them using butter color. What's that, you ask?
WELLS, RICHARDSON & CO. a.k.a. "The Kind That Has No Mud." <-- actual slogan
DANDELION BUTTER COLOR (Made by Wells, Richardson & Co.)
CHARLES HANSEN'S LABORATORY, makers of "Unrivalled Rennet Tablets" and "Ripening Cream" and the "Most Perfect Coloring on the Market"
THE THATCHER MFG. CO. >> Possibly one of the most terrifying ads ever.
F. B. FARGO & CO. << pushing the limit on how many negatives you can fit into one ad
Read more HERE, HERE, and HERE. (Google Books)