The massive testing program began in April after animals from infected herds in New Mexico and Arizona were traced to dairies in southwest Kansas.
"We have the best situation possible in this scenario: complete the first round of testing and find nothing," said Kevin Varner, chief veterinarian in charge of the U.S. Department of Agriculture in Kansas.
People can catch TB, which attacks the lungs, by drinking raw milk from infected cows. But pasteurization kills the bacterium. People who milk cows or work around infected animals also are at risk.