(AP) WASHINGTON An undercover video shot by an animal rights group at an Iowa egg hatchery shows workers discarding unwanted chicks by sending them alive into a grinder, and other chicks falling through a sorting machine to die on the factory floor.

Chicago-based Mercy for Animals said it shot the video at Hy-Line North America's hatchery in Spencer, Iowa, over a two-week period in May and June. The video was obtained Monday by The Associated Press.

Hy-Line said in a statement it has started an investigation "of the entire situation," adding that it would have helped their investigation "had we been aware of the potential violation immediately after it occurred."

The video, shot with a hidden camera and microphone by a Mercy for Animals employee who got a job at the plant, shows a Hy-Line worker sorting through a conveyor belt of chirping chicks, flipping some of them into a chute like a poker dealer flips cards.

These chicks, which a narrator says are males, are then shown being dropped alive into a grinding machine.

In other parts of the video, a chick is shown dying on the factory floor amid a heap of egg shells after falling through a sorting machine. Another chick, also still alive, is seen lying on the floor after getting scalded by a wash cycle, according to the video narrator.

Hy-Line said the video "appears to show an inappropriate action and violation of our animal welfare policies," referring to chicks on the factory floor.

But the company also noted that "instantaneous euthanasia" a reference to killing of male chicks by the grinder is a standard practice supported by the animal veterinary and scientific community.

According to Mercy for Animals, male chicks are of no use to the industry because they can't lay eggs and don't grow large or quickly enough to be raised profitably for meat. That results in the killing of 200 million male chicks a year.

The United Egg Producers, a trade group for U.S. egg farmers, confirmed that figure and the practice behind it.

"There is, unfortunately, no way to breed eggs that only produce female hens," said the group's spokesman, Mitch Head. "If someone has a need for 200 million male chicks, we're happy to provide them to anyone who wants them. But we can find no market, no need."

Using a grinder, Head said, "is the most instantaneous way to euthanize chicks."

Hy-Line says on its Web site that its Iowa facility produces 33.4 million chicks. Based on that figure, Mercy for Animals estimates a similar number of male chicks are killed at the facility each year. Hy-Line did not comment on that estimate.

Mercy for Animals says it will call on the nation's 50 largest grocery chains to include labels on their eggs that say, "Warning: Male chicks are ground-up alive by the egg industry."

Head called that proposal "almost a joke," saying the group had no credible authority, and had questionable motives. "This is a group which espouses no egg consumption by anyone so that is clearly their motive." The video does in fact end with a call for people to adopt a vegan diet, which eliminates all animal products meat, eggs or dairy.

Nathan Runkle, executive director of Mercy for Animals, said most people would be shocked to learn that 200 million chicks are killed a year.

"Is this justifiable just for cheap eggs?" he said.

As to more humane alternatives to disposing of male chicks, Runkle said the whole system is inherently flawed.

"The entire industrial hatchery system subjects these birds to stress, fear and pain from the first day," he said.

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On the Web:

Mercy for Animals video: http://www.mercyforanimals.org/hatchery

Hy-Line International: http://www.hyline.com/