Only 19 of 80 From Herd of Infected Cow Found

Nearly four weeks into their investigation, agriculture officials have tracked down just 19 of the 80 cows that entered the United States along with the Holstein infected with mad cow disease.

These are the cows believed most at risk of carrying the brain-wasting disease because they could have shared contaminated feed that officials consider the probable source of infection.

Investigators are hampered by the lack of a modern tracking and identification system that could have eased greatly the search for the origins of the infected cow and others in its herd.