April 25 (Reuters) - Chemicals maker Dow beat first-quarter profit estimates on Thursday, helped by higher sales volumes as global manufacturing activity shows signs of growth.

The Midland, Michigan-based company reported operating earnings per share of 56 cents for the quarter ended March 31, compared with the average analyst estimate of 45 cents, according to LSEG data. (Reporting by Sourasis Bose in Bengaluru; Editing by Maju Samuel)