In a large bowl, combine the egg, milk, Worcestershire sauce, oats, onion, salt, sage and pepper. Crumble beef over mixture and mix well. , Press into an ungreased 8x4-in. loaf pan. Bake, uncovered, at 350° for 1-1/4 hours; drain., Spread ketchup over meat loaf. Bake until meat is no longer pink and a thermometer reads 160°, about 10 minutes longer. Let stand for 10 minutes before slicing.