Watch for poisonous weeds commonly found in hay
University of Minnesota Extension
Minnesota is home to numerous toxic plants and weeds. Most weeds are not palatable and in a pasture, will be avoided by livestock if adequate forage is available. However, in hay, most livestock cannot differentiate weeds from beneficial long-stemmed forage, resulting in accidental ingestion and possibly a loss in performance or death.
Three weeds commonly found in Minnesota that remain toxic when dried in hay are hoary alyssum, wild parsnip and poison hemlock.