NORMAN — Excellent rainfall during 2013 across much of Oklahoma allowed drought-stressed pastures to rebound. These rainfall events in central and eastern parts of our state saw many ranchers rebuilding cattle numbers.
While rebuilding, many producers have had to make decisions about bulls for the next breeding season. While doing so, herd health and reproductive disease have been major considerations in the context of what age and type of bulls are being purchased.
Perhaps the one reproductive disease for which bulls play a critical role in transmission is that of Trichomoniasis, or “trich.” This disease has been around for generations and, for many years, was thought to be something only states west of the Rocky Mountains had to be concerned with. This is not the case today; many states now have this disease within their borders.
Trich is a highly contagious sexually transmitted disease in cattle that results in abortions and infertility and is caused by a microscopic protozoan parasite Tritrichomonas foetus. The organism colonizes in both bulls and cows, and as bulls age, conditions on the surface of reproductive organs are more conducive for this protozoa to survive and multiply.
Infected bulls and cows look and act normal. The only way to confirm Trichomoniasis infection is by testing. Typically, cattle producers become aware of a problem when cows are pregnancy checked and there are too many open cows, a prolonged calving period or noticeably reduced calf crop.
Reabsorption of the fetus or abortion usually occurs early (one to four months) in pregnancy and females become temporarily infertile. Late-term abortions have been reported but are not common. The majority of infected cows will clear the infection within four to five months of sexual rest.
Immunity to Trichomoniasis is short-lived, and cows are susceptible to reinfection and abortion the following season. Some cows will not clear the infection. Bulls become infected with the Trichomoniasis protozoa when breeding infected females. Those bulls younger than 3 may clear the infection, but bulls older than 3 are generally permanently infected.