Identification of trichomonad-carrier cows.

Seven pregnant cows (gestation durations, 42 days to 7 months) were identified as culture-positive for Tritrichomonas foetus. For 6 of these pregnancies, 2 of the youngest fetuses were aborted, and calves were delivered by the other 4 cows. Two cows became carriers, maintaining trichomonad infections for 6 and 9 weeks after parturition. Carrier cows may be a source of reinfection for their herd mates. Hence, strategies for controlling trichomoniasis might include delaying the time of first breeding and aggressive culling of infected cows.