South African champion Horse Chestnut, who is standing his fourth season at the Hancock family's Claiborne Farm near Paris, Ky., is recovering from colic surgery performed at Rood and Riddle Equine Hospital near Lexington. The problem was corrected without removing any part of the intestine.""He's better this morning," said Gus Koch of Claiborne March 19. "We're pleased with his progress."Horse Chestnut showed signs of discomfort the afternoon of March 17 and was promptly sent to the clinic, where Dr. Alan Ruggles performed the surgery.Horse Chestnut (Fort Wood -- London Wall, by Col Pickering) is expected to miss about four or five weeks of the breeding season and to stay several more days at Rood and Riddle. He covered 28 this year.