Supporters of the bill mobilized after the Interior Department announced last year that it may have to kill thousands of healthy wild horses and burros to deal with the growing population on the range and in holding facilities.
Republicans complained the bill underscores Democrats' misplaced priorities by focusing on animals instead of people, at a time when the nation's unemployment rate is approaching double digits. They also said the measure would place the protection of wild horses and burros above other animals that rely on the rangeland.
"This bill is based on emotion and not science," Rep. Cynthia Lummis, R-Wyo., said during the debate Friday. The Congressional Budget Office estimated that enacting the Restore our American Mustangs Act would cost about $200 million over the next five years.
Currently, the wild herds roam over about 33 million acres of Western land. To comply with the bill, the Interior Department's Bureau of Land Management would need to find an additional 20 million acres, primarily after 2013, at a cost of up to $500 million, according the CBO.
Rep. Nick Rahall, D-W.Va., chairman of the House Natural Resources Committee, said the CBO's estimates don't reflect new language in the bill that makes adding millions of acres of rangeland a goal rather than a legal requirement.
Rahall said the bill will actually save the government money because the Bureau of Land Management will be able to reduce resources now devoted to caring for the animals in corrals. He said slaughtering healthy animals to control their population should not be an option.
"How can a federal agency consider the massive slaughter of animals they are supposed to be protecting?" he said.
An estimated 36,000 wild horses and burros live in 10 Western states. The bureau determines how many wild horses can graze in various areas and rounds up the excess numbers to protect the herd. The healthy animals are kept in pens and put up for adoption around the country.
To date, there has been no comparable bill sponsored in the Senate, which would also have to pass the measure for it to become law.