Disease a major headache for Montana bison ranch

BOZEMAN, Mont. — About 2,600 bison cows and bulls, with 1,800 calves at side, roam the 114,000 acres of the Flying D ranch, but even this vast area and relative isolation can’t protect them from illness.

In fact, the wide-open spaces that make this ranch ideal for bison are also ideal for other wildlife, including an elk herd that harbours brucellosis and spreads it to bison.

Ted Turner, the largest bison owner in the world, bought the Flying D in 1989 and put it under a conservation easement in 1990. It comprises about 175 sq. miles of contiguous property in the southern part of Montana.

However, the bison herd has been quarantined by the U.S. Department of Agriculture since 2010, when some animals tested positive for brucellosis. Chronic infection in the elk herd that frequents the property means the bison herd will never be free of the contagious and untreatable disease.

“The only real solution is going to be a better vaccine,” said ranch manager Danny Johnson.

“Until there’s a better vaccine, there is no chance of us getting off of quarantine because we have to have three consecutive (negative) tests” of the entire bison herd.

Johnson said the Montana Fish and Game department estimates 27 percent of the elk herd in the region carries brucellosis.


Danny Johnson, manager of the Flying D Ranch near Bozeman, Montana, says they have
established supplementary feeding areas to retain bison until the animals are ready for
slaughter because the herd has been quarantined since 2010 after some animals tested positive
for brucellosis. | Barb Glen photo

Since the bison herd is tested only once a year, Johnson said the chances of finding no brucellosis cases in that many bison over three years are virtually nil.

“We were quarantined for brucellosis in 2010, and it’s from migrating elk. We’re never going to get away from that, so basically animals cannot leave here unless they’re on a USDA sealed truck and trailer and going to slaughter, so we try to keep them here as long as we can.”

For the Flying D, that has led to establishment of two Supplemental Nutrition for Animal Performance (SNAP) areas on the ranch. They are essentially feedlots, although Johnson said they’re trying to avoid that term.

Each lot holds 499 head, keeping numbers below the level where commercial feedlot rules would apply. Each allows 800 sq. feet per animal.

“The main reason we’ve gone into it, and actually all the ranches are kind of heading this direction anyway, the longer we can keep (the bison) home, the more comfortable they’re going to be,” said Johnson.

The bison have free choice of grain and can choose from three different kinds of hay so they can follow natural instincts to balance nutritional needs and rumen health.

Animals enter the SNAP facilities at 18 months and are shipped at about 28 months after 180 days on feed.

Young bulls are fed through fall and winter and heifers in spring and summer.

“We’re trying to grow things on this ranch, rather than importing feeds … wherever we can and try to feed them out,” said Johnson.

“All the hay comes off the ranch right now and we’re trying programs with oats and barley. And field peas, we tried that. Just things we can grow here on the ranch.”

About 10 percent of heifers are kept each year as replacements, and the rest are fed out.

During the once-per-year processing, the entire herd is tested, tagged and sorted. It takes about five weeks.

Back in 2010, when brucellosis appeared during random blood test screening, the USDA demanded that the entire herd be tested. That required a second run through the chutes, and Johnson said he thinks the stress left the herd open to an outbreak of mycoplasma. About 800 head were lost to that illness in 2010.

“The herd’s healthy right now,” said Johnson.

Turner owns three other ranches in Montana, six in Nebraska, three in New Mexico, two in South Dakota, one in Kansas and three in Argentina. He owns about 56,000 bison.

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