Factors Affecting the Utilization of Calcium and Phosphorus From Soft Phosphate by Chicks

THE absorption of dietary calcium and phosphorus by the chick depends on a number of factors. Adequate solubility of compounds of these minerals, as indeed of other essential elements, is a primary requisite but co-factors of absorption may also play an important role in the efficient utilization of these nutrients. Hill et al. (1945) determined the solubilities of a variety of phosphates in several solvents and showed that soft phosphate was not as readily soluble as bone meal and tricalcium phosphate. On the basis of these solubility tests, it can be surmised that the relatively low growth and bone calcification often observed in birds fed soft phosphate (as reviewed by Motzok et al., 1956; and Almquist, 1962) may be due at least in part to the low solubility of this type of supplement. On the other hand, the importance of vitamin D as a co-factor in the absorption of dietary…