Chicago Board of Trade wheat futures were slightly lower on Thursday as traders squared their positions ahead of US Department of Agriculture crop data due on Friday. Analysts expect the USDA to show a drop in US winter wheat seedings compared to a year ago. Plentiful global wheat supplies have anchored prices even as traders braced for a smaller US planted area. USDA data on Thursday showed weekly US wheat export sales at 71,500 tonnes, below expectations and smallest in the marketing year that stared on June 1.