Case Report

Suspected M1 aflatoxicoses on a western dairy calf ranch

Abstract

An 8000-unit dairy replacement calf ranch experienced high morbidity and mortality related to exposure of calves to aflatoxin M1 isolated in the milk replacer [place and date not given]. During the six-week exposure period, pre-weaning calf morbidity was 100%, and approximately 3000 calves died. Aflatoxin M1 is an intermediate metabolite of aflatoxin B1, and is found in milk of dairy cows consuming a contaminated ration. Histopathology demonstrated changes in the centrilobular hepatocytes as well as the biliary tree. Serum chemistry values indicated an ongoing liver disorder. Toxicologic evaluation of the milk replacer revealed the presence of aflatoxin M1. Within three days of removal of the affected milk replacer, morbidity and mortality levels returned to baseline levels for this ranch.