Poisonous Plants, Bulletin 415, Preventing livestock losses
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United States Department of Agriculture

Agricultural Research Service

Bulletin 415
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Plants Poisonous to Livestock in the Western States

To view the full document go to /ARSUserFiles/oc/np/PoisonousPlants/PoisonousPlants.pdf

Poisonous plants are a major cause of economic loss to the livestock industry.  Each year these plants adversely affect 3 to 5 percent of the cattle, sheep, goats, and horses that graze western ranges. All too often the losses to individual livestock operations are large enough to threaten the viability of that ranch.

Livestock losses can be heavy if animals:

  • graze ranges infested with poisonous plants when plants are most toxic.
  • are driven, trailed through, or unloaded from trucks onto range or pasture areas infested with poisonous plants. Animals are less selective in their grazing at these times of stress.
  • are not watered regularly.
  • are allowed to become hungry. Such animals are more likely to eat lethal quantities of poisonous plants.
  • are grazed on rangelands early in spring when there is no other green vegetation except poisonous plants.
  • are stressed, such as when they are trucked, penned, or handled (branding, vaccination, etc.).
  • are not limited on how much and how fast they consume the plants.

There are no known treatments for animals poisoned by most poisonous plants. Where a treatment is available, affected animals are usually in remote places and cannot be reached until it is too late to provide the treatment. Furthermore, the stress of handling poisoned animals may increase the probability of death. If the animals recover enough to be handled, treatment should consist primarily of symptomatic treatment except where a specific treatment is known.

Prevention of loss from poisonous plants in general is a problem of range and livestock management. Under normal conditions, some poisonous plants form an important part of livestock diets without negative effects on the animals. Poisoning occurs only when these animals are enticed by hunger or other stress conditions to eat too much too fast.

Symptoms listed for each plant toxicity are those most likely to be observed. Not all symptoms will be seen in all toxicities and signs of poisoning may vary greatly, depending on dosage and the time taken to consume the dose. Also, individual animals respond differently to specific poisons.

To protect your animals from poisoning:

  • Learn to identify the poisonous plants that grow on your range.
  • Learn the conditions under which these plants can be dangerous to your livestock.
  • Develop a grazing plan to improve your range and prevent poisoning. These plans should take into account the poisonous plants on the range, allowing animals to graze them at the most appropriate time or to avoid them.
  • Do not allow animals that have been under stress or that are overly hungry to graze in areas infested with poisonous plants.
  • Provide adequate water for your livestock.
  • Be especially careful when grazing newly acquired livestock on your range.
  • Provide adequate salt and other supplements as needed, but do not put them in an area where poisonous plants are growing
  • Control poisonous plants where feasible.

If your animals get sick, consult your local veterinarian to ensure proper diagnosis and treatment. If a poisonous plant is involved, identification of the plant is essential for any corrective action.

Last Modified: 8/13/2016
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