Hallmark/Westland Meat Packing Co voluntarily recalled all of its beef produced since Feb. 1, 2006. USDA said Hallmark violated rules against the slaughter of "downer cattle" -- that is, animals too ill to walk.

"This is the largest beef recall in the history of the United States, unfortunately," said Agriculture Undersecretary Richard Raymond.

Based in Chino, California, Hallmark/Westland has been closed since early February. Company officials were not immediately available for comment.

The Humane Society of the United States showed videotapes on Jan. 30 showing workers at the plant using several abusive techniques to make animals stand up and pass a pre-slaughter inspection. These included ramming cattle with forklift blades and using a hose to simulate the feeling of drowning.

"A recall of this staggering scale proves that it's past time for Congress and the USDA to strengthen our laws for the sake of people and animals," said HSUS president Wayne Pacelle.

Raymond said the recall stemmed from slaughter of cattle that could not stand at the time of slaughter, although they passed inspection earlier. Packers are required to alert USDA veterinarians in those cases so they can decide if the animal can be slaughtered for food.

In most cases, beef from downer cattle is barred from the food supply. The rule was adopted as a safeguard against "mad cow" disease, a deadly, brain-wasting illness. People can contract a version of the disease by eating tainted products. USDA said there are many other safeguards against mad cow.

'LITTLE HEALTH RISK'

Until now, the largest US meat recall was 35 million lbs (16 million kilos) in 1999.

USDA said the Hallmark/Westland recall ranked as a minor health risk because it involved a violation of inspection rules rather than proof of contamination. Most of the meat products recalled were beef, but a small amount was ground pork, according to the department.

Announcement of the recall will help the search for beef produced by Hallmark/Westland that may be held in freezer plants.

Senate Agriculture Committee Chairman Tom Harkin said in a statement that USDA must toughen its inspection measures before animals are slaughtered to prevent future occurrences.

"How much longer will we continue to test our luck with weak enforcement of federal food safety regulations?" said Harkin, an Iowa Democrat. "Federal regulations exist for a reason - to protect public health. For Hallmark/Westland to issue a recall that goes back two years indicates that violations may have been long-term."