Tracking Trichomoniasis

In today's world of ever increasing input costs, producers are looking for ways to cut expenses.  But cutting out Trich testing may not be the place to shave the budget.

It’s all about weighing risks, relays D.L. Step, DVM, Oklahoma State University Food Animal Extension Specialist, who reminds that Trichomoniasis is no longer a disease associated with just western states’ herds.

“It’s a myth that the Midwest and eastern states no longer have to worry about Trich,” he says. “As animals have been marketed and transported from different parts of the country, bringing in an animal that looks OK has brought in a carrier of Trich. Therefore, the disease is being established in many other states in the U.S.

” According to the Oklahoma Department of Agriculture, this venereal disease has been found in at least 28 states (see map). Therefore, Step advises beef producers to manage accordingly: assess their herds’ risk before they decide to stop Trich testing as a cost-saving measure.

Assessing herd risk

As a DVM and educator, Step often walks producers through the risk-awareness thought process. He says if producers have records, are managing their herd, have very good reproductive efficiency, and are purchasing young virgin bulls or using artificial insemination with semen from reputable companies, then the risk of Trichomoniasis is going to be fairly low.

On the other hand, if a herd is exposed to other animals that may be carrying Trich or if producers don’t have an opportunity to keep records to even realize there is potentially a reproductive problem occurring, or they are bringing in bulls that could be carriers, then the risk is high and, therefore, this disease should be of concern.

Step explains that Trich is a sexually-transmitted disease in cattle caused by the parasitic protozoan Trichomonas foetus. The problem, he finds, is many producers look for clinical signs of this disease because it is, indeed, caused by an infectious organism. However, that is where Trich is tricky – it’s a silent disease.

“The bull is one of the primary carriers,” Step says, “but he will not exhibit any outward abnormal clinical signs.” Furthermore, the organism does not affect semen quality, so a bull can pass his semen test and, yet, be a carrier of T. foetus.

 Efficient transmission

The T. foetus organism resides in the tissues lining a bull’s penis, prepuce, and sheath. Studies show that mature bulls are more likely to become infected and stay infected with Trich. Since there is no treatment, all Trich-positive bulls need to be culled for harvest and replaced.

The usual means of Trich transmission in a herd is an infected bull exposing unexposed cows or infected cows exposing uninfected bulls.

The organism causes varying degrees of reproductive inefficiency, namely early embryonic death. Trich doesn’t interfere with a cow’s ability to get bred, but to stay bred. If infected by Trich, a female may lose her first conception, clear the infection, return to estrus, and conceive a pregnancy that goes to term.

The results of this scenario are a drawn-out calving period within the cow herd if bulls are left with the cows long enough. Therefore, it’s often the open and late cows that are carrying the disease, and they too need to be culled and replaced.

Step reports that the disease is very efficient at transmission. “An infected bull can infect up to 80-90% of the cows he breeds.” A good example of what a herd could experience if 100 cows are exposed to a percentage of infected bulls within a defined 60-90-day breeding season is given in Chart 1.

According to this chart, some 60% of females will show infertility – or, in other words, be open at preg check – therefore confirming that the biggest source of economic loss is from the reduction of calf crop. This isn’t to mention the cost of testing, culling, and replacing infected bulls and females, all which are big economic hits for Trich-infected operations.

Borrowed or leased bulls: A good idea?

Veterinarians greatly caution producers on the practice of borrowing, leasing, or buying used bulls. But Step does acknowledge there can be economics and genetics involved, especially for seedstock producers.

He explains, “There are some older bulls that are very high quality, very fertile, and have good genetics. They just need to be tested before use.” This is a requirement in many states, including Oklahoma, that have intrastate (in-state) regulations in place that require Trich testing of bulls that have a change in ownership/management.

Step continues, “There are going to be cases in which you know the bull, it’s test-negative, and you should be OK. However, if you don’t know the history, it’s not tested, and is having reproductive problems, then that should be a flag. Have him tested or look for another bull,” he recommends. “It all goes back to risk, assessing the risk, and working with your veterinarian.

”Preventing the diseaseExperts like Step agree that if you can keep Trich out of your herd in the first place, you’ll be money ahead. One of the biggest keys to prevention, they say, is know your bull source: buy from a reputable breeder

.Step also recommends these Trich-prevention measures:

• Keep records in order to evaluate the reproductive status of your herd. These can help alert you to a potential problem
• Diagnose pregnancy, i.e. preg check in a timely fashion.
• Cull any open female.
• Trich test bulls about two weeks after breeding season. This is the best early indicator of a Trich problem. Cull any positive bulls immediately for harvest.
• Keep young virgin bulls or test-negative bulls in fences; assess the risk if they cross fence lines or commingle with neighboring bulls.
• Employ Trich vaccination as a management tool in at-risk herds.
• Utilize good husbandry practices: prevent and control other reproductive diseases, keep cows in proper body condition so they can maintain pregnancy.

Other management practices that may be helpful for Trich prevention include the purchase of virgin replacement heifers from known sources. If cattle do run in common on rangelands, make sure the majority of cows are bred before turning out or that only clean, tested bulls are allowed.

State Trich Regulations and Tests Often Differ

According to Oklahoma State’s Dr. D.L. Step, almost every state west of the Mississippi River has interstate regulations that require Trich testing of bulls for state entry. States east of the Mississippi are beginning to see the infection and are also developing regulations. Oklahoma is one of the newest states to also enact intrastate rules, which are very similar to those in Texas, Louisiana, New Mexico, and Colorado.

Still, there are quite a few inconsistencies in Trich regs, relays Bill Barton, Idaho State Veterinarian. Therefore, he says, “It’s really important to check with the individual state of destination to see exactly what the requirements are.” He says the age requirement for bulls that can be considered virgins or have to be tested varies dramatically among states.

Barton says that if you assume all states are 24 months or less like Idaho, “You could be exporting bulls illegally without the proper Trich test.

”Testing protocol is also critical to note. Trich can be diagnosed through culture tests or the newer PCR – polymerase chain reaction – assays. States with newer Trich rules automatically require that bulls have a PCR test for entry into their state.

Barton says there are lots of real specific requirements on a state-by-state basis, therefore, “the best thing is for producers to get with their veterinarian, have him or her call the state of destination, and find out exactly how they want that sample treated.”

Produces Stand Tough On Trich

In east central Oregon, quality genetics and herd health are a priority for Ironside Associates ranch managers Jeff and Edie Palmer. But Trichomoniasis is still consid-ered one of their greatest threats.

“We’ve been a Trich-contact herd five times,” Jeff explains, “and haven’t had a positive bull. In east-ern Oregon, it’s pretty important we stay on top of all that.

”For this reason and more, Jeff believes “it’s very important” to involve his veterinarian in their operation. “For our deal, I wouldn’t do it without a vet,” he assures.

Trich testing of bulls is not mandatory in Oregon, unless they are in a herd that has tested positive for or been exposed to the dis-ease. But ranchers in the Palmers’ Malheur County desired a tougher Trich program, and took imple-mentation into their own hands.

The county cattlemen’s as-sociation sought the help of the county court in promulgating an ordinance to control and eradicate Trichomoniasis in their county, declaring that all bulls, except virgins, being turned onto public grazing allotments located wholly or partially within that county shall be tested and tagged for Trich.

This area encompasses 4.5 million acres of public grazing lands and some 75,000 beef cows. Jeff says transient herds are common because of the amount of grass for rent; but the ordinance has still helped clean up their end of the county.

“The biggest thing about the ordinance is it’s just made everyone aware of the disease. Our vet men-tioned he’s tested bulls in herds that have never been tested,” Jeff relays.

Julie Weikel, state field veterinarian for the Oregon Department of Agriculture, agrees the ordinance has been “hugely helpful” in decreasing Trich, and has even helped change the mindset in this state.