The ‘carry over’ of aflatoxin M1 into the milk of cows fed rations containing a low concentration of aflatoxin B1

Abstract Six dairy cows consuming a diet contaminated with approximately 10 μg aflatoxin B 1 /kg excreted aflatoxin M 1 in the milk, the concentration varying between 0·01 and 0·33 μg/litre with a mean value of 0·.19 μg/litre. Approximately 2·2% of ingested aflatoxin B 1 appeared in the milk daily as the metabolite aflatoxin M 1 . This was a more consistent index of aflatoxin ‘carry over’ than the ratio of toxin concentrations in feed and milk.