Sysco Corp. and U.S. Foods, which sell food to hundreds of thousands of food-service customers, alleged in separate lawsuits that they overpaid for chicken meat for years due to collusion among Tyson Foods Inc., Pilgrim’s Pride Corp., Sanderson Farms Inc. and other companies in the $60 billion U.S. chicken industry. The food-distribution giants represent roughly 25% of the domestic food-distribution business.