WASHINGTON (MarketWatch) - The U.S. economy grew at a 3.0% pace in the first quarter - lower than the 3.2% previously reported - owing mainly to smaller increases in consumer spending and investment in business software, the government said Thursday. Economists surveyed by MarketWatch expected first-quarter growth to be revised up to 3.5%. The latest revision incorporates data that is not available for the first reading of GDP. Consumer spending, the largest contributor to GDP, grew at 3.5% annualized rate in the first quarter, down from the initial estimate of 3.6%. The increase in business investment, meanwhile, was reduced to 13.1% from the original estimate of 14%.