By DEE-ANN DURBIN, AP Business Writer The U.S. dairy industry, the largest in the world, is under severe pressure as the consumption habits of Americans shift. Borden Dairy Co. filed for bankruptcy protection, the second major U.S. dairy to do so in as many months. Borden produces nearly 500 million gallons of milk each year for groceries, schools and others. It employs 3,300 people and runs 12 plants