Oct 28 (Reuters) - Wall Street’s main indexes opened higher on Thursday, led by gains in Caterpillar, Merck and Ford after upbeat quarterly earnings, shrugging off data that showed U.S. economic growth slowed sharply in the third quarter. The Dow Jones Industrial Average rose 54.72 points, or 0.15%, at the open to 35,545.41. The S&P 500 opened higher by 11.16 points, or 0.25%, at 4,562.84, while the Nasdaq Composite gained 68.90 points, or 0.45%, to 15,304.74 at the opening bell. (Reporting by Devik Jain in Bengaluru; Editing by Maju Samuel)