The Food Safety Inspection Service, known as FSIS, and the National Chicken Council, a trade association, stressed that the number of birds who die that way represents a tiny fraction of the billions of chickens that are slaughtered every year.
Chicken production is big in much of the South. Georgia, Arkansas, Alabama, North Carolina and Mississippi are the top five states for chicken meat production.
Earlier this month, 68 House members urged Agriculture Secretary Tom Vilsack to scrap a proposed poultry inspection rule that would speed up cleaning and inspecting bird carcasses, known as evisceration. The lawmakers said in their letter to Vilsack that would result in more birds missing backup slaughter devices and entering the scalding tank alive. The House members also objected to the rule's reduction of 500 to 800 inspector positions.
FSIS Deputy Administrator Phil Derfler said that the Agriculture Department "is using the full extent of its legal authority to protect chickens from inhumane conditions because poorly treated birds can present a food safety concern, and it is ethically appropriate for us to do so."
He said that those efforts led to an all-time low of chickens killed by other than humane methods of .008 percent last year.
"Our goal is always to drive that number as close to zero as possible, and our proposal to modernize poultry slaughter inspection would help do that," Derfler said, by better positioning inspectors to ensure humane treatment of poultry.
Birds that die by means other than slaughter are called "cadavers" and not allowed to enter the food supply. Last year, FSIS records show, there were roughly 680,000 cadavers, down from around 730,000 the year before. FSIS officials say the majority of cadavers are birds that have been dropped into scalding tanks alive.
"Dying other than by slaughter causes tremendous suffering to how ever many birds are subjected to this treatment," said Dena M. Jones, the Animal Welfare Institute's farm animal program manager.
Tom Super, a spokesman for the National Chicken Council, said there's an economic — as well as ethical — incentive to reduce the number of cadavers. He said that when birds miss the automatic knife, an employee is used as backup to keep live birds out of the scalder.
Rep. James Moran, a Virginia Democrat who co-chairs the Congressional Animal Protection Caucus, said he thought the number of chickens "boiled alive" in the U.S. was significant.
"You either feel for other living species, or you don't," said Moran, who signed the letter to Vilsack. "And a lot of people simply don't."
Virginia is 12th in the nation, according to the National Chicken Council.
The animal welfare groups' petition also says that birds aren't always properly stunned, which is supposed to make them insensible to pain before slaughter; and that many birds suffer broken or dislocated bones when they are shackled for slaughter.
Super said that his group issued new guidelines last month requiring stunning to be more effective, with a goal of at least 99 percent of birds effectively stunned and insensible to pain, and corrective action required when it falls below 98 percent. And he said companies must have a monitoring program for wing and leg injuries, and retraining of employees when standards are exceeded.
Derfler, of the FSIS, said the agency works under existing law to ensure humane treatment of chickens, relying on the Poultry Products Inspection Act, which condemns adulterated products, including birds that die by means other than slaughter.
"Under our regulations, right now, if live birds go into the scald tank, we do think that's a prohibited act, under the Poultry Products Inspection Act," Derfler said. "And we'd take action, because the animals would be dying other than by slaughter — they'd be drowning, and not slaughtered in a humane way."