The Utilization by the Chick of Phosphorus from Different Sources

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Abstract
The comparative availability of a number of common phosphorus supplements and pure phosphate compounds has been studied by adding them singly to a basal chick diet very low in phosphorus. When used to raise the phosphorus content of the basal diet to 0.4%, the orthophosphates, including KH2PO4, pure beta tricalcium phosphate and reagent grades of mono-, di-, and tricalcium phosphate, were excellent sources of phosphorus and slightly more available than steamed bone meal. At the same phosphorus level, the defluorinated superphosphate and defluorinated phosphate rock products used in these experiments were good sources of phosphorus, but less available than the pure orthophosphates or steamed bone meal. When used to raise the phosphorus content of the diet to 0.8%, the defluorinated superphosphate and defluorinated phosphate rock, both fused and calcined, were of equal value and were nearly as effective as pure beta tricalcium phosphate or steamed bone meal. Crystalline calcium acid pyrophosphate was well utilized by the chick, while vitreous calcium metaphosphate was poorly utilized and vitreous sodium metaphosphate was only slightly available. Potassium metaphosphate, beta and gamma calcium metaphosphate, alpha, beta, and gamma calcium pyrophosphate, and crude calcium phytate were virtually unavailable. Comparison of the biological availability of the products used in these experiments with their solubility in 0.4% HCl shows that the solubility test is useful only in that insoluble compounds may be eliminated. The results also show that there was no difference in the availability of the different crystalline forms of a given chemical compound. Severe phosphorus deficiency in the young chick results in early loss of appetite, weakness, and death within a period of 10 to 12 days.