Major Toxic Plants and Their Effect on Livestock: A Review

Abstract

Poisonous plants are major causes of economic loss to the livestock industry. Each year these plants adversely affect 3 to 5 percent of the cattle, sheep, goat, and horses that graze ranges. These losses result from death of livestock, abortions, photosensitization, decreased production, emaciation, and birth defects. In addition to these losses are those of increased management costs associated with such things as fencing, altered grazing programs, and loss of forage. Suggestions are included for the prevention of livestock poisoning by plants. Various species and classes of livestock are reported to be affected by toxic plants particularly in the dry and early rainy seasons when feed is in short supply. A more extensive survey is required to document all poisonous plants in the rangelands and to identify the major toxic principles in the different species possibly pharmacological activity. This review presents the current knowledge on the identity of plants known to have poisoned livestock and research conducted into these toxic plants. Many of the plants identified are considered toxic on the basis of world literature. Research is needed to determine not only which plants represent a potential risk for animal health and production but also their photochemistry and toxicology. It is strongly recommended that veterinarians document plant poisoning cases through government reporting services and that university and government veterinarians, scientists, and extension agents investigate episodes of plant toxicosis and publish their findings. This would help identify toxic species for further photochemical and toxicological studies and possibly pharmacological activity.

Keywords: Bladder tumors, Bracken fern, Castor oil, Kochia, Photosensitization and toxicity.