The results were all negative, for the presence of mad cow disease, and acording to the USDA, no further testing on those animals is planned.
The government previously performed a "rapid screening test" on 67 adult cows from this ranch and herd, all of which tested negative.
The Agriculture Department announced that the second case of mad cow disease in the U.S. was traced to a beef cow born in Texas 12 years ago and slaughtered last November at a pet-food plant.
This is the first time the disease is found in a U.S. born cow. The first case, in December 2003, was found in a dairy cow imported from Canada.
Dr. John Clifford, Agriculture's chief veterinarian, says the case was linked to the herd in Texas through DNA evidence, citing the herd had been quarantined and no infected animal carcass entered the food chain.
The government has not identified the cow's owner or the town it came from. Considering the cow's age, Clifford speculates it may have been infected before 1997, when the ban forbidding the use of cattle parts in animal feed was imposed.
Officials are currently trying to identify herd mates born within one year of the infected cow's birth, as well as offspring born within the last two years.
The Agricultural Department confirmed the case last Friday but needed to wait on DNA analysis to confirm the cow's origin, which proved difficult because its breed was mislabeled and its tissue was mixed with parts of other cows.
Officials insist beef from Texas and the U.S. in general is the safest in the world. Said Sen. John Cornyn, R-Texas, "It's clear to me that our safeguards worked as designed and the animal in question never entered the human or animal feed supply."
Initial screenings of the cow in November had indicated a presence of the disease; later, more sophisticated tests came back negative. The results bothered the Agricultural Department's internal investigator, who ordered a second round of tests in early June; the results of which came back positive, confirming the cow was infected.
