The Obama administration will probe consolidation in the agriculture industry and enforce antitrust laws where it finds excessive market power hurting competition, Attorney General Eric Holder said Friday. Holder and Agriculture Secretary Tom Vilsack spoke in Ankeny, Iowa, at the first of five workshops on competition and regulation in the agriculture industry. Holder said they have already received 15,000 comments on the subject. 'Is today's agriculture industry suffering from a lack of free and fair competition in the marketplace?' Holder said to a standing-room crowd of about 700 people at a community college. 'That is the central question.' Consolidation in meat, packing and seed markets have lowered food prices while pressuring growers and threatening the life of rural economies, Vilsack said. Companies that abuse their dominant market position to hurt competition will face Justice Department action, said Christine Varney, head of the antitrust division. 'Big is not illegal,' Varney told reporters outside the workshop, when asked whether the administration plans to break up large companies. 'We are not looking to restructure the economy. We are looking to enforce the law wherever the facts take us.' The department is investigating whether patents on biotech seeds are being abused to extend or maintain companies' dominance in the industry, Varney said. The department is looking broadly at the intersection of patent and antitrust laws, she said. 'There is a very robust patent system in this country and if you are abusing a patent to extend or maintain a monopoly, that is not legal,' Varney said. 'We are looking at those very important issues.' Monsanto has begun switching seedmakers and growers from soybeans with the Roundup Ready gene, which was in 93 percent of U.S. soybean seeds last year, to the newer Roundup Ready 2 Yield version in advance of the original's patent expiration in 2014. DuPont Co., the second-biggest seed company, says Monsanto is using incentives and penalties to switch the industry to the new product in a way that unlawfully extends the Roundup Ready monopoly. Varney declined to comment more specifically on the focus of the probe. 'Monsanto's place in seed is something that is a competitive issue that is before all of us,' Iowa Attorney General Tom Miller said. Iowa also is investigating the St. Louis-based company, he said. Holder said he will aggressively review mergers in the agriculture industry. He highlighted the Justice Department's Jan. 22 lawsuit against Dean Foods Co. over its acquisition of Foremost Farms USA's consumer-products division, saying the deal hurts competition in the sale of milk to schools and stores in several states. The partnership with the Department of Agriculture is meant to also address competition through regulation, Holder said. Vilsack highlighted concerns about increased concentration and integration in meat-packing and rapidly shrinking spot markets. 'Are farmers and ranchers in this country currently getting a fair shake? Is there sufficient transparency?' Vilsack said. 'Seed companies in some cases control the lion's share of market. Is that good or bad for farmers?' Sen. Charles Grassley, R-Iowa, said he will explore legislative remedies to boosting competition. The cooperation between the Justice and Agriculture departments is unprecedented and 'fills a big void,' he said. 