In a previous issue we discussed an emerging disease in Missouri cattle known as trichomoniasis or ‘trich’. This issue provides an excellent opportunity to bring producers up to date on recent changes in Missouri state regulations.
Trichomoniasis is a sexually transmitted reproductive disease of cattle that is caused by the protozoal organism Tritrichomonas foetus. Bulls serve as the primary carriers of the disease and often show no outward signs of infection. Infected bulls transmit the disease to cows upon natural service. Cows infected at breeding frequently abort the pregnancy in the first trimester and return to estrus. For most cows, a 90 day interval is required to clear the infection at which point the cow can again become pregnant. Since some immunity persists from initial infection the cow has a much higher likelihood of carrying the subsequent pregnancy to term. A small percentage of cows may abort in late gestation or become chronic carriers of the disease themselves. Because most herds have no prior immunity to ‘trich’, introduction of the disease to the herd by an infected bull can be devastating to the following year’s calf crop resulting in fewer calves born and a majority of calves born late in the calving season. The economic impact can vary substantially from one farm to the next, however, greater than 50 percent open cows at the end of the breeding season would not be an uncommon finding after the introduction of ‘trich’ to a herd.
Due to increased prevalence of the disease in the state and the potential for significant economic impact, Missouri first required testing of all non-virgin bulls or bulls 24 months of age or older entering Missouri from other states. As of June 1, new regulations took effect regarding movement of bulls within the state, requiring that all non-virgin bulls or bulls 30 months of age or older that are sold through private treaty, leased, bartered or traded in Missouri will require a ‘trich’ test within 30 days prior to change in ownership or possession. Bulls 24 months of age or older that are sold through a livestock market will also be tested unless destined for slaughter. Enforcement of these regulations begins September 1. In November the age requirement for testing all bulls will change to 24 months. Available tests include three consecutive cultures at 7 to 10 day intervals or a single PCR test. Samples are collected by a veterinarian and submitted to an approved laboratory. Bulls must have official identification and accompanying test results at change in ownership. Positive bulls must be sent to slaughter. Further regulations exist for handling animals from a positive herd.
The most important factor for control is being careful about the source of new cattle introduced into the herd. Virgin heifers and bulls are the safest bet. Avoid buying open or short-bred cows from unreliable sources. Consider testing all bulls annually prior to the breeding season and maintain good perimeter fencing to keep neighboring bulls out and your bulls in. Use of a controlled breeding season followed by pregnancy evaluation allows for prompt identification should a problem arise.
Dr. Darren Loula, DVM, is owner of Christian County Veterinary Service, LLC, a mobile large animal vet clinic.
