Kentucky Derby winner Animal Kingdom was recovering Thursday after his owners announced the colt had undergone surgery on June 30 for a fracture in his left hind leg. The Team Valor International ownership group said the horse underwent the operation at the New Bolton Center in nearby Pennsylvania, with veterinarian Dean Richardson inserting two screws to compress a hairline slab fracture. Animal Kingdom, who should resume walking in a few weeks, captured the Derby in only his fifth career start.