Milkvetch

Milkvetch (Astragalus bisulcatus) is a perennial herb of the Pea (Fabaceae) family, and a specific type of locoweed. Milkvetch is native to central and western North America and parts of Canada. Milkvetch has purple showy, pea-like flowers and a thick woody root-stock stem.

Milkvetch has the ability to accumulate high amounts of selenium. Seeds contain the highest selenium concentrations, followed by the flowers, stems, leaves, and roots. The elevated levels of selenium in A. bisulcatus can cause acute or chronic selenium toxicity in chickens. Due to the presence of swainsonine, animals usually present with symptoms of both selenium poisoning and locoweed poisoning.