SALT LAKE CITY — A state legislator is hoping he can stop bison from infecting cattle with a sexually transmitted disease that causes early termination of females' pregnancies and can potentially cost cattle ranchers tens of thousands of dollars.
The incurable disease, trichomoniasis, is the target of Republican state Sen. Darin Peterson, a Nephi rancher who is concerned that domesticated bison aren't undergoing the same testing for the disease that cattle are.
That can become a problem if a certain cow catches a bison's eye and won't let a fence stop it from mating, he said.
"They are very aggressive animals when they get out," Peterson said. "It's not an affront to buffalo guys. Buffalos are just acting like buffalos when they go out. It's not their fault."
Peterson's opened up a bill file to require domesticated bison, which are commonly called American buffalo, to be tested for the disease once a year, just as cattle are.
Infected cattle are typically sold to slaughter. The disease isn't harmful to humans who eat cattle that have been infected.
But for cattle ranchers who depend on their cows for calves, the disease can be devastating.
"Anyone in the cattle business or bison-raising business, that's their objective to produce offspring and sell those offspring. If they're not able to do that they're not going to be profitable," said Earl Rogers, the Utah Department of Agriculture's assistant state veterinarian.
Peterson said many cattle ranchers have 35 cows for every bull. If one female is infected and passes the disease along to the bull, the entire herd could be quickly infected.
State and industry officials couldn't immediately say how widespread the disease might be in Utah.
Trichomoniasis isn't fatal to cattle or bison. A bull carries the infection for life, but a cow's immune system can destroy the microscopic organism after several months and it can possibly get pregnant later.
"To have that spread out really wreaks havoc. You want that breeding season as tight as possible. You want those things timed correctly," Peterson said.
In 2002, there were about 700 bison in Utah, according to the National Bison Association. That does not include bison at Antelope Island, which Peterson said he would exclude from his proposed legislation because they are isolated.
Dave Carter, executive director of the bison association, said trichomoniasis is one his group's smallest concerns.
"It's not even on our radar screen," he said.
South Dakota, which has one of the nation's largest bison populations with about 40,000, has never had a case of trichomoniasis reported in that breed, said Sam Holland, state veterinarian for the South Dakota Animal Industry Board.
However, he said the disease is more common in Western states and that if a bison carried the disease, it's possible it would spread to cattle. Mating between the two species does occur, he said.
"It's not common at all, but it's sure happened. It will happen if they're grazed together," Holland said.
There has also been concern in the West that bison will spread among other domesticated herd animals brucellosis, another sexually transmitted disease that can terminate pregnancies, create weak offspring or cause a reduction in milk production.