AP: Corn prices extended their rally Monday amid heightened concerns about tight supplies even as demand remains strong from ethanol producers, livestock owners and overseas buyers. Corn rose 27.5 cents, or 5.2 percent, to settle at $5.5575 a bushel. It was the third straight gain for corn, which is at its highest price since the recession intensified in the fall of 2008. Much of the trading action was driven by a U.S. Agriculture Department report issued Friday that lowered this …