The situation is generally described something like this, “we were cleaning up the yard / garden” or “trimming the hedges / tees” with the conversation ending something like this “when we went back outside there were ____ dead cattle. The incidence of accidental poisoning generally hits a seasonal high in the fall due to short pasture supply and accidental introduction of poisonous plants.

Numerous landscape plants are commonly associated with livestock poisoning. One of the most common and most toxic are English or Japanese Yews. The most common Yew poisoning symptom is “found dead”. Never discard or plant yews in areas where livestock may have the opportunity to graze.

Several tree species have toxic components in the buds, leaves and seed pods. The most common tree species of concern are black locust (leaves, pods, seeds), buckeye / horsechestnut (leaves, nuts, bark), red maple (leaves), red oak (acorns, buds), and wild cherry (leaves). Toxicity concerns related to leaves are generally associated with consumption of wilted or damaged leaves while seed and pod consumption are associated with animal intake due to short pasture supplies.

When cleaning up the garden avoid tossing tomato and potato plants into pastures since these plants are closely related to the nightshade family (Solanaceae). These plants are generally unpalatable but if pasture is limited and these are the only green plants available livestock curiosity may result in unwanted consumption.

Another accidental poisoning of ruminants can be triggered by the first frost of the year. Sorghums such as milo, sorghum x sudangrass hybrids, sudangrasses and johnson grass contain a compound known as dhurrin which after freezing is converted into hydrocyanic acid or hydrogen cyanide, also referred to as prussic acid. Prussic acid poisoning can be rapid and lethal. These forages can be safely grazed after a frost if: (1) the crop was safe to harvest before the frost meaning sudangrass hybrids were least 18 inches tall and sorghum-sudangrass hybrids were at least 24 inches tall and (2) the plant tissue is allowed to dry seven to ten days following the frost.

Accidental poisoning can be avoided by being aware of toxic plants, using good judgment when disposing of yard and garden plants and monitoring pastures for frost damaged forages. For more information about toxic plants visit http://www.vet.purdue.edu/depts/addl/toxic/cover1.htm. Further information related to Frost and forages can be found at http://www.livestocktrail.uiuc.edu/pasturenet/paperDisplay.cfm?ContentID=8038.

Justin Sexten, 618-242-9310, sexten@uiuc.edu
Date: 10/10/2006