NEW YORK, Aug 22 (Reuters) - McDonald's Corp has amended its board, the fast-food chain said on Monday, and the director being replaced had been targeted by activist investor Carl Icahn who sought to tighten the company's animal welfare policies.

Sheila Penrose, who will retire effective Sept. 1, was one of two incumbent board members Icahn sought to replace with his own nominees. In May, investors reelected all 12 of McDonald's directors, including Penrose, handing Icahn a loss in that battle over the treatment of pregnant pigs by pork suppliers.

Days after losing that fight, Icahn ended a similar effort targeting supermarket chain Kroger Co over the way meat producers confine pregnant pigs to crates.

Penrose, who was a McDonald's director for 15 years, led the board's sustainablity and corporate responsibility efforts, the company said in a statement.

Investors have also criticized the Chicago-based company for having too many directors who have served for too long. Chairman Enrique Hernandez has been on the board since 1996, for instance.

On Monday, McDonald's said it elected three new board members: Marriott International Inc Chief Executive Officer Anthony Capuano, Johnson & Johnson Executive Vice President Jennifer Taubert and Salesforce.com Inc Chief Financial Officer Amy Weaver. Their tenures begin Oct. 1. (Editing by David Gregorio)