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November 30, 2005
Reference: Forage Beef.ca

Knowledge Nuggets

• Plants are not easily classified as poisonous or non-poisonous. Some poisonous plants are good forage when eaten in small amounts. Most poisonous plants are dangerous only when consumed in large quantities, and even then may be harmless at certain times of the year. However, a few species are extremely poisonous even in small amounts.
• Depending on the type of poison and the amount of plant material eaten, an animal’s reaction may range from reduced performance to death.
• Prevention of livestock losses depends on a good knowledge of poisonous plants and the seasons when they are the most dangerous. Many poisonous plants are native to rangeland. These plants are normally not grazed because they are unpalatable or few in number. Unusual conditions that force livestock to eat toxic quantities of poisonous plants may cause large losses.
• Many poisonous plants increase in abundance when rangelands are overgrazed.
• The palatability and toxicity of poisonous plants varies seasonally.
• To manage poisonous plants, ranchers should be able to recognize poisonous plants, know what class of livestock is most susceptible, and know in what seasons or under what conditions poisonous plants are most dangerous.
• The best way to reduce livestock losses from poisonous plants is to maintain a good cover of forage species.
• Grazing hazards to avoid include:
  - Trailing hungry stock through poisonous plant areas. While on the move, animals tend to graze any green plant along the trail. Trailing too far or too fast can increase poisonings.
  - Scarcity of forage for long periods of time. Hungry animals are less selective of what   they eat.
  - Lack of salt or minerals.
  - Grazing too early in spring, before forage species have adequate growth.