Toxicity of Echium plantagineum (Paterson's Curse). 1. Marginal toxic effects in Merino wethers from long-term feeding

Abstract

Groups of 10 Merino wethers were pen-fed pelleted diets containing 80 or 20% Echium plantagineum, for four periods of 12 weeks alternating with four similar periods on control diet. Mild liver damage, characteristic of pyrrolizidine alkaloid poisoning, aas induced in one wether consuming 80% E. plantagineum. The other animals on the 80% diet showed only a small increase in the size of the hepatocytes, which was not unequivocally due to alkaloids. There were no effects on liver function, serum enzymes, weight gain or wool growth attributable to alkaloids. The 80 and 20% Echium diets contained 0.11-0.15 and 0.032-0.047% alkaloid respectively, indicating that approximately onequarter to one-third of the alkaloid of the fresh plant was lost during diet preparation and storage. Echlum feeding induced a high rate of destruction of pyrrolizidine alkaloids in the sheep rumen. The conversion of the Echium alkaloids into pyrrolic metabolites by microsomal preparations from livers of the experimental sheep taken at necropsy was unaffected by the feeding schedule.