Absorption of Calcium and Strontium from Milk and Nonmilk Diets

Abstract

The availability of calcium from milk was contrasted with that from CaCl₂ in rats, rabbits and human subjects, and with calcium supplied with grain in cattle, rats and rabbits. In cattle, the retention of single oral doses of Ca⁴⁵ and Sr⁸⁹ gave essentially the same results as the conventional determination of calcium balance. Calves on a milk diet absorbed and retained a very high percentage of the calcium present. Similar animals on a hay diet and grain diet showed a much lower absorption and retention. A calf on hay and grain for 30 days showed the typical high calcium utilization when returned to a milk diet. The calcium retention of an 11-year-old cow was improved by the addition of dried skin milk in the ration. Young and old rats absorbed about one and a half times as much calcium⁴⁵ from milk as from a solution of CaCl₂ or from CaCl₂ + grain. Young and old rabbits showed no increased Ca⁴⁵ absorption from milk. Three out of 4 human subjects absorbed an average of 34% ingested Sr⁸⁵ from CaCl₂ as compared with 82% from milk.