Research shows that numerous factors influence the action of poisons and the severity of a sheep's or goat's reaction to them. These factors include the amount eaten and over what period of time, the chemical nature of the poison, the part of the plant and condition of the plant, the amount of fill in the rumen prior to ingestion of the substance, species of animal poisoned, and the general health of the ruminant prior to eating the poisonous plant. Another key influencer is the size, age, and sex, of the animal.Contrary to popular belief, sheep and goats do not inately know which plants are poisonous and which are not. Sheep and goats learn this knowledge through social interactions of the herd. With only a few exceptions, most adult goats will not eat poisonous plants unless they are forced to do so.
Read the full article, "Why Poisonous Plants Sometimes Lethal, Sometimes Not," in the Summer 2007 edition of the Sheep & Goat Health Report published by the National Institute of Animal Agriculture. For a free subscription, send an e-mail to NIAA@americanagriculture.org.
List of plants known to be poisonous to animals in the United States
