The option for players to launch diseased cows from trebuchets has returned, in addition to smaller animals like pigs and sheep.
Federal authorities had suggested that it might take weeks, even months, to track the origins of the diseased cow.
United States officials had initially said the diseased cow, from a herd in Canada, was no more than 4 1/2 years old.
The fallout from the discovery of the diseased cow continued to roil the cattle markets, while injecting a new issue into the presidential race.
Government officials emphasized that nervous tissues from the diseased cow were separated at the time of slaughter and did not enter the human food supply.
If the diseased cow was not a downer, the rationale for testing only those cows would be cast into doubt.
Mad-cow disease is contracted when the animals eat organs of other diseased cows.
The diseased cow was not found until Dec. 23, and a recall order was issued.
If the diseased cow was walking, the entire logic of the testing system would unravel.
Its one diseased cow was slaughtered in January and probably made into pet food.