DES MOINES — Gov. Terry Branstad on Monday maintained a fervent defense of his administration’s move to shift management of Iowa’s Medicaid program from the state to four private health care companies.Iowa’s $4.2 billion Medicaid program serves 560,000 residents.Branstad’s administration said the shift will provide the same — and perhaps better — services at a lower cost.Providers said at a public hearing this past week that the state is moving too quickly.