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A new study shows that juniper bark can cause cattle to abort their calves
Juniper trees and cattle are two common sights in Crook County. The combination of the two, however, can have fatal consequences.
November 12, 2012
Most businesses can’t absorb a 33 percent loss, but some Oregon ranchers may potentially lose that much of their calf crop to a recently-discovered culprit.
In the last five or six years, some Oregon ranchers noticed that a number of their pregnant cows aborted their calves a few days after browsing on juniper trees.
Cory Parsons is a Livestock Range Agent with OSU Extension Service for Baker and Union counties in Oregon. He is working closely with Crook County OSU Range and Livestock Extension Agent Tim Deboodt on a study concerning the toxicity of western juniper.
The realization that there was a potential problem with cows grazing juniper was from a producer that Parsons works with in Baker County.
“Fall 2006/Spring 2007, we had a local veterinarian stop in, Dr. George Risdal was his name, and just asked what information we had regarding western juniper that was similar to ponderosa pine needle abortion,” Parsons said.
He explained that when a pregnant cow consumes enough quantity of ponderosa pine needles, it causes late-term abortion or early parturition (birth). That usually happens during the third trimester of gestation and most often in the eighth and ninth month. It is believed that a chemical called isosupressic acid (ICA) is what causes the early term parturition.
“He (Dr. Risdal) had been noticing that same issue in three or four livestock producers in the Burnt River area. They were doing some riparian restoration work on Burnt River itself and they were using western juniper as large woody material or riprap along the stream corridors for protection, buffers, and barriers.
“They went from one property to the next property. Over a series of years, he was getting the same phone calls and the same concerns and seeing the same determination that clinical ponderosa pine needle and yet there are no ponderosa pine around — it was juniper. Eastern Oregon is similar to here (Crook County) as far as winter feeding areas on irrigated crop aftermath and that’s what these fields were, but they’d have a pile of juniper trees or juniper trees in the riparian area.
“The ranchers would see their cows grazing on them on occasion and then we started seeing calves sloughed off. The producers weren’t necessarily making the association, but the veterinarian started watching them from year to year to year and moved downriver during this restoration project. He stopped in and said, ‘I’m not sure what’s out there, but something’s happening with western juniper,’” Parsons said.
Parsons and Deboodt sent some juniper samples to the Poisonous Plant Research Laboratory (PPRL) in Logan, Utah for preliminary analysis.
“I collected some western juniper needles, bark, and some berries and sent it to them. Within a week, they contacted me — very interested in doing a more in-depth evaluation of western juniper,” Parsons said.
They sent him a list of all sorts of plants that had various stages of isosupressic acid, the chemical that they were associating with ponderosa pine needle abortion. Among the list were lodgepole pine needles and some other species of juniper, but not western juniper yet.
In 2009, Parsons was awarded a grant from the Oregon Beef Council to look at the geographical extent of isosupressic acid. Their goal was to find out if there is a geographical difference between northeast Oregon versus Central Oregon versus Southwestern or Southern Oregon.
“Also,” Parsons said, “we wanted to do a feeding trial — buy some heifers, get them bred and do a feeding trial.
That first year, Parsons and the scientists from the Poisonous Plant Lab scraped and collected 2,000 pounds of juniper bark.
“They (PPRL) took it, dried it, sampled it, and did the analysis on it and ground it all up,” Parsons explained.
Typical cow gestation is 280 days. Many calves at 250 days gestation, 30 days premature, are born viable.
The first year, they used six cows in the study that were at 250 days gestation.
“Two out of those six, or 33 percent, aborted their calves within the first five days,” Parsons said.
He went on to explain that those cows were also being fed free-choice grass hay and free-choice water as well as juniper on a daily basis. They continued feeding western juniper to the other four cows that didn’t abort, until they had full-term births.
There are still a lot of questions they are continuing to consider such as the possibility that cows can become acclimated to western juniper, or maybe there is some genetic strain, or perhaps there are saliva, kidney, or liver function considerations.
During the course of the study, Parsons wondered if the western juniper might be having an effect on wildlife. He talked to the Poisonous Plant Lab regarding that and judging from their ponderosa pine needle studies, other wildlife ruminant species, except bovine species such as Bison, are not affected by isosupressic acid.
“The really important thing is that it’s the last trimester,” explained Parsons. “Isosupressic acid is a vasoconstrictor, which means it constricts the vascular system, starving the calf of oxygen. That doesn’t have much impact on the fetus when it’s small, but when it hits the third trimester, it requires a large oxygen supply. The fetus is what triggers parturition — it’s a stress mechanism.”
Not only is early parturition detrimental for the calf, it also takes a huge toll on the cow as well.
“The signs and symptoms on the cows are pretty dramatic and severe, because they haven’t gone through all that soft-tissue dilation, and they haven’t developed a mammary system, so they don’t have milk for the calf. It can be fairly traumatic,” said Parsons.
The connection between western juniper and early parturition in cows has been slow in coming for a variety of reasons.
Some calf loss is expected and during the last trimester, some cows are still out on the range, so they are not observed. Many things can cause a cow to abort and until recently, ranchers have been attributing it to something other than western juniper. Sometimes, a rancher cannot find all the calves they were expecting to be born, which can be due to predation or possibly the cow wasn’t pregnant to begin with.
Ranchers can absorb a normal 2-to-3-percent calf loss each year.
“At a 33-percent loss to western juniper abortion, there aren’t very many producers who can absorb that kind of financial loss,” Parsons said.
After that first year’s findings, Parsons and other OSU agents, including Deboodt in Crook County, knew it was critical to continue the study.
“We sat down the next year and said, ‘Let’s look at a geographical range,’ so we did over a three-day period and hit over 35 different locations in 13 counties across northeast, central, and southeast Oregon. We sampled 10 trees in 35 locations, so 350 samples,” Parsons explained.
They separated out bark, needles, and berries, and ran chemical analysis on all of them. What they found was that the isosupressic acid was high in some, but not in others.
Isosupressic acid is a member of a family of chemicals called labdane acid. When they looked at the overall labdane acid content, it was as high if not higher than ponderosa pine needles. So now, even though isosupressic acid could be the culprit, they don’t exactly know which of the chemicals is causing the problem.
They were, however, able to make some other decisive conclusions.
“When we analyzed all these 35 different areas we were able to sit down and allocate a low risk, a medium risk, and a high risk to the areas, based on the analysis that came back. What we found out is that it varies across the state, and it varies even more from tree to tree within a location,” Parsons said.
The variations may be due to the age of the tree, soil, whether it’s a male or female tree, or a number of other conditions.
What they did find was that every location had some areas of high levels and they do know that .5 percent of isosupressic acid in a plant tissue will cause abortion.
Now, they are doing a seasonal survey in three regions, Baker, Lake, and Crook counties. They are sampling the same 10 trees every two months for two years to see if there are variations between seasons.
Abortion is not the only reproductive concern they have with western juniper. About a year and a half into this study, Bobbi Riggs, who used to work in the Crook County Extension office, wondered if it could have an affect on a cow’s ability to breed or conceive.
“There was one producer on the backside of Post that was noticing that for a two-year period, he was having some reproductive issues (they didn’t get bred) with his heifers when he ran them through a particular pasture with access to western juniper.”
After receiving another grant from the Oregon Beef Council with matching funds from PPRL, they decided to include the effect of western juniper on breeding into their study. They bought 20 heifers to do two feeding trials. One to see if they can induce early parturition and then in 60 days start it again to see if they will have trouble conceiving.
According to Parsons and Deboodt, there are a number of precautionary things producers can do to avoid possible exposure. One, is to trim branches up to where the cows can’t reach them. Two, is to make sure cows have plenty of good alternative feed available. Three, is to clear out down trees. Four, is to not graze in areas with high concentrations of western juniper during the last trimester. Five, is to manage the body condition score in the cows, and try to keep it between 4 and 6.
Researchers don’t know why cows will eat juniper bark, needles, and berries. It might be recreational grazing due to boredom, or weather induced, or lack of feed, but whatever the reason, browsing on western juniper at the wrong time can cause early parturition in cows.
For more information including the list of vegetations that contain isosupressic acid, contact Cory Parsons at 541-523-6418 or email@example.com