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United States Department of Agriculture

Agricultural Research Service

Title: SWITCHGRASS (PANICUM VIRGATUM) TOXICITY IN RODENTS, SHEEP, GOATS AND HORSES

Authors
item Stegelmeier, Bryan
item Elmore, Susan - INTEGRATED LAB SYSTEMS
item Lee, Stephen
item James, Lynn
item Gardner, Dale
item Panter, Kip
item Ralphs, Michael
item Pfister, James

Submitted to: Poisonous Plant Global Research and Solutions
Publication Type: Book / Chapter
Publication Acceptance Date: May 31, 2006
Publication Date: June 20, 2007
Citation: Stegelmeier, B.L., Elmore, S.A., Lee, S.T., James, L.F., Gardner, D.R., Panter, K.E., Ralphs, M.H., Pfister, J.A. 2007. Switchgrass (panicum virgatum) toxicity in rodents, sheep, goats and horses. Poisonous Plants Global Research and Solutions, Chpt. 19,pp. 113 - 117.

Interpretive Summary: Switchgrass (Panicum virgatum) commonly used in pastures and as a cover crop, can poisons animals but its toxicity has been difficult to reproduce experimentally. The purpose of this study is to establish a model for switchgrass toxicity, identify switchgrass toxins and determine their toxicity, document the clinical and histologic lesions of switchgrass poisoning, and predict when and under what conditions switchgrass is toxic to livestock. Syrian hamsters, horses, sheep, goats and horses were fed or dosed orally with fresh switchgrass, switchgrass hay or ground switchgrass. Feeding trials varied from 30 to 180 days. Ground switchgrass was analyzed for toxins (glycosisidic steroidal alkaloids). Diosgenin was identified as the major toxin with smaller amounts of yamogenin. Animals fed switchgrass lost weight and body condition, but did not develop photosensitivity. No crystalline lesions were detected in the livers of these animals. However, goats fed green switchgrass with green alfalfa did develop liver lesions with with rare inclusions and sun burn consistent with phylloerythrin-associated photosensitivity. These findings suggest that switchgrass can be toxic under certain conditions and that goats may be most susceptible to poisoning. Additional work is needed to better define when and under what conditions poisonings are likely to occur.

Technical Abstract: Switchgrass (Panicum virgatum) commonly used in pastures and as a cover crop, can poisons animals similar to Kleingrass. However, switchgrass toxicity has been difficult to reproduce experimentally. The purpose of this study is to establish a model for switchgrass toxicity, identify switchgrass toxins and determine their toxicity, document the clinical and histologic lesions of switchgrass poisoning, and predict when and under what conditions switchgrass is toxic to livestock. Syrian hamsters, horses, sheep, goats and horses were fed or dosed orally with fresh switchgrass, switchgrass hay or ground switchgrass. Feeding trials varied from 30 to 180 days. Ground switchgrass was analyzed for glycosisidic steroidal alkaloids. Diosgenin was identified as the major sapogenin with smaller amounts of yamogenin. Animals fed switchgrass lost weight and body condition, but did not develop photosensitivity. No crystalline lesions were detected in the livers of these animals. However, goats fed green switchgrass with green alfalfa did develop hepatocellular necrosis with rare canilicular crystalline inclusions and radiation induced dermatitis consistent with phylloerythrin-associated photosensitivity. These findings suggest that switchgrass can be toxic under certain conditions and that goats may be most susceptible to poisoning. Additional research is needed to better define when and under what conditions poisonings are likely to occur

Last Modified: 10/31/2014
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