The Efficiency of Utilization of Phosphorus by the Albino Rat

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Abstract
The utilization of phytin, lecithin and disodium phosphate phosphorus by growing albino rats was studied by means of balance experiments, efficiency of utilization being expressed as the difference in retention divided by the difference in intake. In one experiment disodium phosphate phosphorus and crude soy bean lecithin phosphorus were utilized to the extent of 63.9% and 69.2%, respectively. Phytin phosphorus was utilized to the extent of 49.2%. The corresponding calcium utilizations were 41.9, 32.0, and 16.1%, respectively. In another experiment of longer duration the disodium phosphate phosphorus was utilized to the extent of 45.0%, and the phytin phosphorus to the extent of 42.5%. This low utilization of disodium phosphate phosphorus was apparently due to a low level of calcium in the ration which made calcium the limiting element instead of phosphorus. The corresponding calcium utilizations were 67.0 and 51.5%, respectively. The higher amount of phosphorus in the feces of the phytin rats apparently signified lower absorption. The pH values for intestinal contents of individual rats varied much, but the average pH value, 6.60, for the phytin rats was higher than that, 6.50, for the disodium phosphate rats. This higher average pH value for the intestinal contents of the phytin rats was associated with a lower utilization of phytin phosphorus. The intestinal wall extracts for both the disodium phosphate rats and the phytin rats showed the presence of a phytate-splitting enzyme. No correlation was found between the enzyme activity of the extracts and the utilization of phytin phosphorus. However, the pH of the intestine may influence the activity of the phytase.