Effect of feeding milk from goats fed tansy ragwort (Senecio jacobaea) to rats and calves.

Dried tansy ragwort, which contains pyrrolizidine alkaloids (PA), was fed to lactating dairy goats. Milk containing 7.5 ng of PA/g (dry weight basis) from these goats was fed to rats and calves. Rats fed a goats' milk diet for 180 days with a calculated total PA intake of 0.96 mg/rat had swollen hepatocytes of centrilobular distribution, and biliary hyperplasia, indicating PA involvement. Rats fed tansy ragwort at dietary levels of 1%, 0.1%, 0.01% and 0.001% (corresponding to PA intakes of 39.77, 5.04, 0.52, and 0.05 mg/rat) showed swollen hepatocytes, megalocytosis, biliary hyperplasia, and fibrosis. The histopathologic changes in the milk-fed rats and those given 0.001% tansy ragwort in the diet were similar. Definitive changes in 2 calves fed goats' milk were not detected. The results with rats indicate that PA are transferred in goats' milk and may produce hepatoxic effects.