American businesses expanded their payrolls less than expected, a key measure of private sector hiring indicated Wednesday. ADP Research said that private payrolls rose by 44,000 in July, missing estimates for 65,000 jobs. The lower-than-expected payroll growth may not reflect a lower demand for labor but a lower supply of available workers. Typical hiring patterns, meanwhile, are changing as employers react to shifting macro-economic conditions,” ADP economist Nela Richardson said in a statement. The mining and natural resources sector shed 6,000 jobs in July, according to ADP.