Abstract
A factorial experiment was conducted with multiparous rats (6 months old on average) fed one of eight diets prepared according to an L8 (27) -type orthogonal design for 13 weeks to determine the influence of dietary protein, calcium and phosphorus on kidney, femur, and utilization of calcium, phosphorus and magnesium. Factors studied were protein, calcium and phosphorus content in the diet and feeds were prepared containing both the standard amount according to AIN-76 and double the amount. The results obtained were as follows: 1) An increase in protein intake alone caused an increase in urinary calcium, but no change in calcium absorption. An increase in phosphorus intake alone caused a decrease in urinary calcium excretion. A concurrent increase in protein and phosphorusintake caused a decrease in urinary calcium excretion. 2) A high protein or a high phosphorus intake caused a significant increase in kidney weight. A high phosphorus intake increased markedly the concentrations of calcium, phosphorus and magnesium in the kidney. 3) Pathological examination revealed that calcification and degeneration had occurred in the distal parts of the renal tubule due to high phosphorus intake. 4) There were no differences in the effect on femur weight produced by dietary differences in calcium, phosphorus and magnesium concentration.
