EMORY MILKVETCH (ASTRAGALUS-EMORYANUS VAR EMORYANUS) POISONING IN CHICKS, SHEEP, AND CATTLE

Abstract

A severe outbreak of Emory milkvetch poisoning in cattle and sheep occurred near Roswell, New Mexico, USA, in the spring of 1975. Mortality averaged 2-3% and morbidity averaged 15-20%. Emory milkvetch collected from the infested area contained miserotoxin measured as 5-9 mg of NO2/g of plant (dry weigt). Chicks fed extracts of Emory milkvetch showed toxic signs when fed 1 dose as 300 mg of NO2/kg of body weight and died within 5-8 h when fed milkvetch as 400 mg of NO2/kg. A sheep fed Emory milkvetch for 7 days in the form of 38 mg of NO2/kg per day developed signs of nitro poisoning on the 7th day. Cattle were poisoned or died when fed Emory milkvetch as 12-20 mg of NO2/kg for several days. The toxic signs observed in the field and under experimental conditions were similar.