Blaming a downswing in fresh-chicken prices and an upswing in energy costs, Pilgrim's Pride Corp. said its fourth-quarter profit dropped 31.1 percent to $11.3 million, or 28 cents a share, compared to year-earlier results. In fourth-quarter 1999, the company (NYSE: CHX, CHX.A) earned $16.4 million, or 40 cents a share.