Germany has been chosen as the launch venue for McDonald's new global advertising campaign as the giant food chain seeks to boost business with a younger image and a new slogan -- "I'm lovin' it." The new slogan, dreamed up by a German ad agency, Heye & Partner, replaces "We love to see you smile" and will debut in German television ads on Tuesday evening. The campaign is to spread to more than 100 countries by the end of the month with the new campaign hitting U.S. shores on Sept. 29. The company has declined to say how much it is spending on the new campaign, which features American pop star Justin Timberlake. The revamped adverts are part of a new push by the burger giant that also includes the appointment of a new chief executive and the closure of hundreds of restaurants.