Democratic lawmakers want to know why the Agriculture Department has ordered new tests on tissue from a cow that had been declared free of Mad Cow disease seven months ago.
A brain sample from the cow is being sent to England for further study because a third round of tests came back positive late Friday. The Agriculture Department's inspector general suddenly ordered those tests last week.
USDA has not explained why the new tests were ordered. The inspector general's office, an independent arm of the agency, would not comment, saying a brief statement would be issued Tuesday.
Senior Democratic lawmakers say they will ask the department to explain why new tests were ordered and why it took months to do so.