Managing cattle to prevent trich
April 13, 2014
If a producer doesn't preg-check in the fall, spring calving season may be the first sign of a trichomoniasis (trich) outbreak in a herd.
Knowing the signs of trich, managing for prevention and efficiently implementing a clean-up plan if necessary can reduce or eliminate issues resulting from this costly disease.
"Trich can have a very severe economic impact to a producer once their herd is infected with it," said Idaho State Veterinarian Bill Barton "It's a venereal disease caused by the organism Tritrichomonas foetus that shows no symptoms in bulls. What you will notice is a much greater range in age of fetuses when preg-checking in the fall, or a higher percentage of opens. Or, if you don't preg check, you're going to notice it when you start calving because there won't be nearly as many babies on the ground."
If producers see signs of trich in the spring — typically in the form of an extended calving season resulting from infertility and abortions the previous breeding season — immediately begin testing of all bulls on the operation to determine if any of them are carriers before the breeding season starts, recommends Wyoming State Veterinarian Jim Logan.
"If they find a bull that tests positive this time of year, it creates quite a mess. The associated female cattle will potentially remain infected up to eight months. Typically a female will clean up spontaneously as long as she isn't re-exposed for three to four heat cycles, but you're still looking at 100-120 days where she could potentially re-infect any bull that breeds her. This time of year that scenario creates a real disaster for a producer," said Logan.
Barton suggests waiting up to 150 days before re-exposing a potentially exposed female, adding that there is currently no approved treatment of an infected animal in the U.S. for trich, or a reliable way to test female cattle for the disease.
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"There is a vaccine available for cows, but it does not prevent infection. However, it may speed up the rate at which an infected cow clears the infection from her reproductive tract," said Barton.
While it is the producer's decision to retain potentially and/or known infected females and keep them separate from bulls for 100-150 days, or cull them, there is only one option for a bull that tests positive for trich.
"Once infected, the bull needs to be culled from the herd and slaughtered," Barton said.
Prevention is preferred to treatment by both producers and veterinarians, and there are several management practices that can be implemented to reduce the chance of getting trich in a herd.
"One of the best ways to control trich and keep it out of a herd is to use artificial insemination. In some operations that's either already done or is a possibility, and in others it is not feasible, but it does help," said Logan.
For those who do rely fully on bulls for breeding, keeping a younger bull battery will also aid in prevention, Barton said.
"Do not keep your bulls past four years of age. The trich organism lives in the sheath of the bull, and inside the sheath and prepuce there are crypts. As the bull ages those crypts get deeper, and create a more favorable environment for trich to thrive in. Younger bulls can get trich also, but the environment in their sheath is not as favorable for growth and maintenance of the disease as is found in an older bull," he said.
On the female side, proper management and culling practices are key components of preventing the spread of the disease. Ideally, late and open cows, especially from a known infected herd, should be sold for slaughter only.
"It is very important that people cull open and late cows. Furthermore, they should never buy open females from an unknown source or sources, and then turn them in with their herds. It's much easier to control this disease from the bull side than the female side, and females are one area where I feel we can make improvement in addressing and reducing trich," Logan said.
Avoiding common-allotment grazing situations whenever possible is another way to reduce the likelihood of catching the disease, as is testing all non-virgin bulls annually.
"Since 1989, Idaho has required that all non-virgin bulls, as well as every bull 24 months of age or older, be trich tested annually, and that applies whether they are run on private or public lands. The first year we implemented that law, we tested about 13,000 bulls and had over 350 come back positive for trich. In comparison, last year we tested 23,000 bulls and found four or five positives. Annual testing works," said Barton.
Wyoming requires intrastate testing for any non-virgin bull run in common with more than one producer's cattle, and also for change of ownership of non-virgin bulls. Any non-virgin bulls imported into the state are also required to be tested for trich.
While such testing helps, Logan said ultimately the control of the disease falls on the vigilance of individual producers.
"The best advice I can give, and the key to getting this disease under control, is going to be the industry stepping up and self-policing. No matter what the rules are, be they state or common-grazing allotment rules, if only one person doesn't follow them and everyone else does, and that one person has one infected bull, it can infect everyone else's cattle. The states can require things, but as long as there are those individuals who refuse to comply and step up to the plate this will remain a serious issue," he said. ❖