Effect of a purified or corn-skim milk diet on retention and tissue distribution of manganese-54 in calves.

Calves were fed a corn-skim milk or a purified diet to determine if the large differences in manganese metabolism in rats fed such diets also occurred in ruminating calves. The calf purified diet was similar to the rat purified diet but with potassium bicarbonate and sodium bicarbonate added as buffers to be suitable for ruminating calves. In contrast to the huge differences in rats, retention of manganese-54 was the same in calves fed the corn-skim milk diet as in calves fed the purified diet. It is unlikely that the minor differences in the diets caused such large differences in effects between calves and rats. A likely reason for the difference is the functional rumen in the calf. The active rumen may metabolize ingredient(s) that affect manganese absorption in the rat and, therefore, would not be in the small intestine to affect absorption by the calf.