Studies on Phosphorus Assay Techniques

Recent studies (Motzok et al., 1967) showed that for maximum growth and bone calcification of chicks fed soft phosphate, it was necessary to supplement the diet with additional calcium (0.15–0.2% as calcium carbonate), even when sufficient soft phosphate was used to raise the level of calcium in the diet to 1.12%. These data suggested that for maximum utilization of the inorganic (available) phosphorus of the basal ingredients, about 0.2% additional calcium, in a readily available form, was required in diets supplemented with soft phosphate. This suggestion was tested in an assay procedure for estimating the relative availability of phosphorus from supplements, and the results are presented in this paper. Sufficient calcium carbonate to provide 0.2% calcium was added to the basal diet (Motzok et al., 1967) to raise the calcium level to 0.46%. Tricalcium phosphate (chemical grade) and soft phosphate were added to the basal diet containing 0.46% calcium . . .