U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version



Veterinary Clinics of North America: Food Animal Practice, Volume 27, Issue 2, July 2011, pp 419-428; doi:10.1016/j.cvfa.2011.02.013


Many problematic pyrrolizidine alkaloid (PA)-containing plants are foreign invasive weeds that invade pastures, fields, and ranges, and contaminate feeds and food. Others are native plants that may increase or expand on field edges or in disturbed areas. Most are unpalatable, only becoming a problem for livestock when alternative forages are unavailable, or when they are included in hay and other harvested feeds. Human poisoning is most often a result of contaminated grain or flour, although several poisonings have resulted from the use of PA-containing herbal preparations. Major PA plants and their specific health-related characteristics are discussed individually.