Opinion of the Scientific Panel on Contaminants in the Food Chain on a Request from the European Commission Related to Pyrrolizidine Alkaloids as Undesirable Substances in Animal Feed

The term pyrrolizidine alkaloids (PAs) describes a group of more than 350 individual compounds that share as a basic structure one of the four necine bases platynecine, retronecine, heliotridine, or otonecine. PAs are produced as secondary metabolites of more than 6000 plant species, belonging to the families of Boraginaceae, Compositae (Asteraceae) and Leguminosae (Fabaceae) and occur world-wide. The pattern of PAs in plants varies largely, depending on the plant variety, climatic conditions, period of sampling and part of the plant analysed. Basic alkaloids seem to accumulate in the seeds, whereas the respective N-oxides dominate in the green parts of a plant. It is assumed that PAs are among the most widely distributed natural toxins affecting wildlife and livestock. In farm animals, however, acute intoxications caused by PAs are rare, as animals avoid PA containing plants if other feed is available. However, this recognition fails in preserved forages such as silage and hay.