Poisonous plants are a major cause of economic loss to the livestock industry. Two poisonous plants common to Oregon are poison hemlock and Western water hemlock. Ingestion of either by humans or livestock typically results in death.
The monthly grazing capacity of a pasture can be stated as animal unit months, AUM for short. It is calculated by estimating the amount of forage an animal eats each day — 2.5% to 3% of its body weight — times 30 days.