under which authorities say there is little risk of illness . Raymond said cattle that had lost the ability to walk since passing pre-processing inspections were slaughtered without an inspector having examined them for chronic illness -- a practice he said violated federal regulations and had been going on for at least two years . Watch video of cows being abused '' Federal regulations are aimed at preventing the spread of bovine spongiform encephalopathy , or BSE -- the scientific name for `` mad cow '' disease . It 's important to keep downed cattle out of the food supply because they also may pose a higher risk of contamination from E. coli or salmonella because the animals tend to wallow in feces and have weaker immune systems , according to AP . Raymond said the average age of the cattle involved is 5-7 years , meaning they were likely born long after a 1997 ban on ruminant feed , and that the incidence of BSE in U.S. cattle is `` extremely rare . '' `` We do not know how much of this product is out there at this time . We do not feel this product presents a
-LRB- CNN -RRB- -- A slaughterhouse that has been accused of mistreating cows agreed Sunday to recall 143 million pounds of beef in what federal officials called the largest beef recall in U.S. history . Officials said this is the largest recall in the United States , surpassing a 1999 recall of 35 million pounds . Keith Williams , a U.S. Department of Agriculture spokesman , said investigators have found no cases of illness related to the recalled meat . But Dick Raymond , the undersecretary of agriculture for food safety , said there was a `` remote probability '' that the meat from the Westland/Hallmark Meat Packing Company in Chino , California , could cause illness in humans . The amount of beef -- 143 million pounds -- is roughly enough for two hamburgers for each man , woman and child in the United States . The largest U.S. meat recall before Sunday came in 1999 , when about 35 million pounds of product possibly contaminated with listeria were ordered off shelves . USDA officials said that was Class I recall , involving a known risk to human health . Sunday 's action was a Class II recall ,