Effects of Intake and Calcium to Phosphorus Ratio on Absorption of these Elements by Sheep

Abstract
Feeding rations containing Ca:P ratios of 0.8:1, 2.8:1 and 6.0:1 to growing lambs had no effect on the amount of calcium or phosphorus absorbed. The amount of either calcium or phosphorus absorbed was directly related to the amount fed. Excretion of metabolic fecal calcium was independent of the amount of either calcium or phosphorus absorbed since it remained essentially constant on the three ratios. Metabolic fecal phosphorus excretion, however, was significantly affected by both calcium and phosphorus absorbed. Within the ranges studied the amount of metabolic fecal phosphorus excreted increased as the phosphorus absorbed increased and decreased with increasing calcium absorption. The smallest excretion of metabolic fecal phosphorus occurred with the ration containing a 6.0:1 Ca:P ratio. The ratio of absorbed calcium to phosphorus with this ration, however, was 1:1. The specific activity of the phosphorus of the saliva was observed to be a good indication of the specific activity of the phosphorus of blood serum 10 days after a subcutaneous injection of P32.