Ranchers steer clear of juniper risk with OSU's help

man in boots stands next to a young juniper tree
Cattle can come in contact with juniper trees while grazing but have no desire to eat it unless hungry. (Photo by Lynn Ketchum.)

OSU research discovers common tree causes premature birth in pregnant cows

When a veterinarian in eastern Oregon noticed a pattern of dead calves, he asked the OSU Extension Service about it. The university identified western juniper as the culprit.

OSU researchers discovered that cows that eat bark, berries or branches from western juniper trees late in pregnancy are more likely to abort their calves or give birth early. OSU researchers found that the tree contains toxins known as labdane acids. These chemical compounds constrict the flow of oxygen to a fetus. The researchers estimate that juniper causes 5 to 10 percent of lost cow pregnancies. Until OSU's investigations, the tree's harmful effect on pregnant cattle was unknown.

Since then, OSU Extension experts have taught ranchers about juniper's harmful effects. They've also crafted strategies for steering foraging cows away from the tree and its debris. OSU is also investigating whether juniper consumption inhibits conception.

Oregon's ranchers sold $654 million of cattle and calves in 2012.

Sources: Tim Deboodt, a range management specialist with OSU Extension in Crook County; USDA's National Agricultural Statistics Service.

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