...The California Horse Racing Board adopted a regulatory amendment last Thursday that will require synthetic surfaces at the state's major Thoroughbred racetracks by the end of 2007. The amendment states that any track that conducts four consecutive weeks of Thoroughbred racing must install a polymer synthetic type racing surface before it can receive a 2008 racing license. The decision affects Bay Meadows, Del Mar, Golden Gate Fields, Hollywood Park, and Santa Anita..