WASHINGTON  Military researchers have dressed live pigs in body armor and strapped them into Humvee simulators that were then blown up with explosives to study the link between roadside bomb blasts and brain injury. For an 11-month period that ended in December, researchers subjected pigs and rats to about 200 blasts, according to Pentagon documents and interviews. The explosions have ranged in intensity, wounding some of the pigs and killing others. Roadside bombs are the top killer of U.S. troops in Iraq and Afghanistan. MILITARY: Studies shed light on brain injuries from blasts The research on pigs has determined that body armor does not worsen brain injury, said Jan Walker, a spokeswoman for the Defense Advanced Research Projects Agency, or DARPA, which conducted the study. The military feared body armor would deflect the force of blasts toward the head and increase the risk of brain injury. The research also shows that body armor protects troops' lungs and is critical to surviving blasts. "If use of animal subjects in testing results in our ability to save lives or prevent injury to our troops, we're confident this is the right thing to do," Walker said. Pigs without body armor died from blasts within 24 to 48 hours, while those with armor survived "significantly higher blasts," she said. Blasting pigs raises "red flags," said Martin Stephens, vice president for animal research issues at the Humane Society of the United States. "This is a worthy goal, trying to prevent soldiers from being injured by roadside bombs," Stephens said. "I think the relevance of this is highly questionable. People are not pigs." Col. Geoffrey Ling, who led the study, said pigs are good subjects because their brains are more similar to human brains than those of rats. Pig hearts and lungs are also similar to humans'. The Pentagon complied with policies that ensure that a minimal number of animals were used in the testing and that they were treated humanely at all times, Walker said. Scientists discovered details that will help protect troops, said Michael Leggieri, director of the Pentagon's Blast Injury Research Program. "The bottom line to everything we do in this program is to protect the soldier," he said. DARPA declined to say where the tests had taken place. The next round of the testing is scheduled for later this year. Stephens called on the Pentagon to end testing on pigs. "Is this the best they can do after several years of losing soldiers to roadside bombs?" he said. U.S. car companies used live animals, including pigs, for crash tests until the early 1990s. They stopped after protests from animal rights groups, such as People for the Ethical Treatment of Animals. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more