Tall larkspur can be deadly for cattle.

Tall larkspur (wild delphinium) grows in patches in moist areas along streams and in aspen groves. It is more of a problem for cattle than the low larkspur that tends to grow all over the foothills.

In years past, when my family had cattle out of the Bureau of Land Management range in the summertime, this was a serious problem. There were old bones in many of the larkspur patches — grim reminders of other ranchers’ losses in earlier years, and in 1967 we lost a cow and a calf along the creek. After that, we always rode our horses out onto the range a week or so ahead of when the cattle went into those various pastures and chopped down all the larkspur patches so the cattle wouldn’t eat them.

Tall larkspur is high in protein and cattle like it — and if they eat too much it will kill them. There are several different species, however, with different toxicity levels. The plants in different regions cam also be different, even within the same species, partly due to growing conditions on a particular year, but also some genetic differences in the plants. Some patches seem to be deadly every year and it’s best to either get rid of them or avoid grazing those areas during the time of year they might be a problem.

How much a cow has to eat to be poisoned can vary, however. If it’s a dry year and larkspur is the greenest plant in that pasture, cattle generally consume a lot of it.

Daniel Cook, (research plant physiologist) and Clint Stonecipher (range scientist) at the Poisonous Plant Research Lab in Logan, Utah, have done some grazing studies in Custer County Idaho with Sarah Baker (Idaho Extension educator) in Challis, and a few years ago Dr. Cook gave a talk in Salmon to livestock producers about larkspur.

“In Utah where we’ve done grazing studies, cows usually don’t eat larkspur until it is flowering and into the pod stage, but in eastern Idaho it’s a different species,” he says.

“It all depends on which species of larkspur you have, and the other forage available. The ranchers in Idaho contradicted me when I tried to tell them that cows only eat larkspur during the flower stage. Ranchers in the Salmon area said, ‘That’s not what happens here!’ I learned something, and we came out and did a grazing study and sure enough, in the Challis/Salmon area, the cows were eating it differently,” says Cook.

“The larkspur there is a different species and grows in a different community of plants — in drier areas (sagebrush hills, but in wet spots in those dry hills). The larkspur in our region in Utah is at high elevations, mainly found in aspen groves, in a plant community where it’s always wet. There are still plenty of other green plants around it, whereas in drier areas the larkspur may be the only green plant,” he says.

“Regardless of species and where it grows, larkspur is very palatable and cows eat it readily. Cattle can eat enough larkspur in part of a day to poison themselves. There are alkaloids in larkspur that cause paralysis of muscles and the cow can’t ruminate properly and bloats. Once these animals becomes laterally recumbent (down flat, and unable to get up) you can’t save them,” he explains.

One of the other scientists at the lab, Ben Green, has been trying to see if there might be a gene marker that could be used to select for animals that are more resistant to larkspur, compared with animals that are more susceptible. “It is ongoing research but what we’ve observed so far is that there are differences in animals in their susceptibility to larkspur poisoning. Then the question is whether we can select for animals that are more resistant. If it is heritable this might be a tool we could use in the future,” he says.

“The best strategy for larkspur right now is grazing management. In some regions, like Lemhi and Custer Counties in Idaho, the larkspur is patchy, along the stream bottoms,” Cook says.

On private land a person can spray it, but that’s not allowed on public land (BLM or Forest Service allotments). One solution is just to chop it down so the cattle won’t eat it — a few days ahead of cattle turnout, so the chopped-down plants are dry and not as palatable.

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