Facts about Sunn Hemp Toxicity

Sunn hemp (Crotalaria juncea L.) is an annual plant widely grown in the tropics. The genus Crotalaria includes some species known to be toxic to animals. Development of seed-producing cultivars for the continental United States at Auburn University, AL, has raised the question of whether its seeds and forage are toxic. This review will present the evidence reported in the literature on the presence of toxic compounds in sunn hemp seed and foliage and other Crotalaria species found in the United States and their effect on animals. Results from research on sunn hemp demonstrate it is a valuable source of forage without toxic effects. The seed does not cause acute toxicity to domestic animals because it has only a small amount of the toxic pyrrolizidine alkaloids characteristic of the genus Crotalaria. Therefore, its presence as a feed contaminant does not pose a problem. However, sunn hemp seed should not be incorporated in animal diets because, depending on the amount in the diet and the length of time that the diet is fed, it may cause weight loss and potential death. Conflicting reports found in the literature regarding seed toxicity of C. juncea appear to be caused by the amount of seed included in the diet, length of time the diet was fed, and animal species that consumed it. Statements indicating that sunn hemp forage is toxic seem to be due to misinterpretation of the literature and unwarranted extension of the toxicity problems found in other Crotalaria species to sunn hemp.