Thursday, April 9, 2009

Some pasture plants poisonous to cattle

By David Burton

University Extension

There are several common plants in southwest Missouri pastures that are considered poisonous to livestock according to Eldon Cole, University of Missouri Extension livestock specialist.

The good news is that these poisonous plants rarely result in deaths.

“One such plant is hemlock, a biennial that is tall growing, purple-spotted and hollow stemmed. Locally it’s often called wild carrot. It’s probably already four to six feet tall and begins its spring growth in February or early March,” said Cole.

The classic hemlock poisoning symptoms for cattle include salivation, diarrhea, nervousness, trembling, convulsions and coma.

According to Cole, the poisonous plant concern usually results when the only green vegetation for them to eat is poison, as was the case with the hemlock and the Holsteins.

“It usually takes more than just a bite or two of most toxic plants to cause problems. Livestock seem to have a sixth sense that steers them away from even attempting to graze toxic plants like hemlock, nightshade, buttercup, cocklebur, pokeweed and wooly croton.

Some limited research with other species hints that the ability to avoid poisonous plants could be learned by grazing with their mothers.

According to Cole, every year the most animal deaths from a toxic plant are caused by the ornamental shrub Japanese yew.

“It’s not uncommon to hear of some well-meaning person trimming their yews and throwing the clippings over the fence to cattle, sheep or goats. In those cases, death is almost guaranteed,” Cole said.

The University of Missouri Guide Sheet G4970, “Plants Poisonous to Livestock” is available at extension centers or online at:

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