U.S. economic activity expanded from early April to late May and growth was expected to continue at a “modest” to “moderate” pace against the backdrop of declining oil and gas investment, the Federal Reserve said on Wednesday. In its Beige Book report of anecdotal information on business activity collected from contacts nationwide, the U.S. central bank said most of its regional Fed banks reported that while manufacturing had either held steady or increased, growth was tempered by the downturn in the oil and gas industry.