Influence of a High Level of Dietary Cadmium on Cadmium Content in Milk, Excretion, and Cow Performance

Abstract

Three Holstein cows were each given 3.0 g of Cd daily (2 equal doses) for 2 wks. by gelatin capsules. There was a sharp drop in concentrate consumption for the first few days of Cd administration but, by the 2nd week, consumption returned to normal. Milk production declined sharply for several days and then increased appreciably, but to a level still substantially lower than that of controls during the last 5 days Cd was given. When Cd treatments ceased, milk production increased by 50%. Fat content of milk was elevated considerably during the week when production was not reduced. Cows given Cd lost considerable weight. There were no other clinical manifestations of toxicity. As determined by the chromic oxide indicator method and twice-daily grab samples, fecal excretion of Cd for the 2nd week averaged 82% if that given. The Cd level in the urine was below the limits of detectability of the method (0.5 ppm of urine). The Cd content of the milk was less than 0.1 ppm of the milk, which was the lower reliability limit of the procedure used. On this basis less than 0.022% of the amount administered appeared in the milk. In vitro studies demonstrated that Cd combined with the casein and whey protein fractions of the milk readily, with the amount combined being linear when levels from 1.0 to 25.0 ppm are added to milk. Smaller amounts were present in the lactose and mineral fractions.