Investigations of the incidence of bovine trichomoniasis in nevada and of the efficacy of immunizing cattle with vaccines containing Tritrichomonas foetus.

Trichomonas cultures taken from 2389 bulls showed that approximately 4.7% of them were infected. Correlation of these data with the ranches from which diagnostic samples were obtained indicated that in the period of 1984 through 1987 26.7 to 44.1% of ranches had at least one infected bull. Thirty-four 18-month-old Holstein heifers were assigned to one of three groups, controls n = 12 animals, soluble vaccine n = 11 animals, and whole vaccine n = 11 animals to determine the effect of Tritrichomonas foetus vaccines on the reproductive performance of T . foetus infected animals. Heifers were bred with T . foetus infected bulls beginning two weeks after the second T . foetus vaccination. All immunized animals developed antibody titers of at least 1:1000 following vaccination. In addition, all control and immunized animals became infected with T . foetus . However, the duration of infection was approximately two weeks shorter in immunized animals. Approximately 42% (5 of 12) of control heifers remained infected with T . foetus for the duration of the experiment, while only 18% (2 of 11) of each of the vaccine groups remained infected for the duration of the experiment. Finally, 27% (3 of 11) of heifers in each of the vaccine groups were pregnant at slaughter, while none of the control heifers were pregnant at slaughter. Therefore, both vaccine formulations appeared to protect heifers (P<0.05) from fetal loss due to trichomoniasis.