The announcement, which gives authorities powers to enforce preventative measures, was made soon after state agriculture officials announced four new poultry farms had initially tested positive for the virus.
Iowa, the top egg-producing state in the United States, is the third state to declare a state of emergency because of the viral outbreak, which either has led or will lead to the extermination of up to 21 million chickens and turkeys nationwide.
Minnesota and Wisconsin declared states of emergency in April.
Iowa’s state of emergency is effective immediately now and will be in force until at least the end of May, depending on developments in the outbreak, Branstad told a news conference.
Dozens of countries have imposed total or partial bans on U.S. poultry and poultry imports since the outbreak of avian influenza was discovered in December.