Chronic hepato-toxicity of Senecio erraticus in calves from two 50-day feeding periods in consecutive years.

One-year-old male Holstein Fresian calves were fed low doses of Senecio erraticus during two 50-d periods in consecutive years to determine its chronic effect on the liver. Toxic liver effects were determined by monitoring serum levels of hepatic enzymes, bromosulphthalein retention (BSP), and histopathological changes in the liver at times before, during and after Senecio ingestion. A gradual increase in BSP retention was observed at days 60 and 90 during the first feeding period. Histological studies of the liver showed hepatocellular megalocytosis and karyomegaly, and hypertrophy of Kupffer cells in both groups. Periportal fibrosis, bile duct proliferation and the presence of periportal hyperchromatic and hypertrophic hepatocytes was seen after the second feeding period.