Beef breeding herds susceptible to disease

BROOKINGS, S.D. -- Trichomoniasis is a reproductive disease that cattle producers should keep in mind when preparing for the upcoming breeding season, says Russ Daly, South Dakota State University Extension veterinarian.

BROOKINGS, S.D. -- Trichomoniasis is a reproductive disease that cattle producers should keep in mind when preparing for the upcoming breeding season, says Russ Daly, South Dakota State University Extension veterinarian.

"Perhaps the one reproductive disease for which the bull plays a critical role in transmission is that of trichomoniasis, or 'trich,'" Daly says.

Daly explains that although this disease has been around for generations, for many years it was thought to be something only states west of the Rocky Mountains had to concern themselves with. That changed for South Dakota cattle producers back in 2004, when more than 40 herds were detected with the disease and were faced with the task of cleaning it up.

A cooperative effort between the South Dakota Animal Industry Board and cattle producer organizations resulted in the implementation of regulations that not only tackled importation of the disease, but Daly explains the effort also reduced the spread of the disease within the state.

These regulations involved testing of all non-virgin bulls moving into the state or between herds, as well as the prohibition of open cows being sold back into breeding herds.


"While South Dakota has enjoyed several years of very few new infections, other surrounding states have not been as fortunate," Daly says. "Trich is very much at the top of their producers' minds as it was for South Dakotans 10 years ago."

About trich

Trich is caused by a protozoal organism that lives indefinitely in the sheath of an infected bull. Once it's transmitted to a female through breeding, it causes an inflammation in the reproductive tract that results in the loss of the pregnancy. While infected cows can clear themselves of the infection, bulls remain positive for life.

Therefore, Daly says detection strategies for this disease come down to testing the bull.

"Testing for trich is among the most-discussed aspects of the disease right now," he says. "We have come a long way over the last 10 years in the methods used for detecting the organism."

What has not changed, Daly says, is the location and means of collecting a sample. He explains that the preferred sample is still a scraping from inside the bull's sheath.

"This is where the protozoa live, protected by the microscopic peaks and valleys in the skin inside the sheath," he says.

But Daly says where we used to need to culture (grow) the organism to detect it, today cattle producers can take a sample and submit it for polymerase chain reaction (PCR) testing.


"This is a very sensitive diagnostic technique that can detect just a few organisms, as well as those that are no longer living," Daly says.

He explains that the culture method was fraught with enough shortcomings (survival of the organism in temperature extremes on the way to the lab was one of them) that regulations required taking three samples at weekly intervals from the bull in order to ensure that an infection was not missed.

While states and laboratories have embraced PCR testing for trich, there remains controversy about testing methods.

"The issue is that every lab has its own special method for testing," Daly says.

He explains that some require samples be submitted in culture pouches and some will recommend submitting them in a tube of saline. Some labs and states do not want veterinarians to pool (combine) samples, while others are fine with it for two or three bulls. And then there are the slightly different techniques employed in the PCR testing itself.

Daly says it's these differences between labs and state testing regulations that have some people concerned to the point where a special summit meeting is scheduled for April to discuss the development of standardized procedures.

"In theory, the possibility exists that one lab might do a better job than another when it comes to detecting trich. For practical purposes, this is yet to be shown," he says. "However, it is possible that such efforts may result in more standard, across-the-board testing requirements coming down from state agencies."

Overall, Daly says improvements in test sensitivity and in awareness of trichomoniasis have significantly reduced the risk of its introduction into our cattle herds overall.


But he reminds cattle producers that trich is a long way from being eradicated -- and will remain a consideration for cattlemen for a long time to come.

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