Halliburton Co said on Friday that it reduced headcount by more than 6,000 during the first quarter due to the prolonged slump in oil prices. The oilfield services provider said revenue dropped 40.4 percent to $4.2 billion in the quarter ended March 31. The company also said it would now hold its earnings conference call on May 3, instead of April 25, to accommodate the April 30 deadline for its merger with Baker Hughes Inc. (Reporting by Manish Parashar in Bengaluru; Editing by Savio D’Souza)