Phosphorus Availability Studies with Feed Grade Phosphates

THE biological availability of phosphorus from inorganic sources for the chick has been reported by Gillis et al. (1954), Motzok et al. (1956), Nelson and Peeler (1961), Miller and Joukovsky (1953) and others. The results of Nelson and Peeler (1961) indicated that practical type diets could be used in critical chick phosphorus assays. In many studies of this nature, dietary adjustments have been made to keep a constant calcium:phosphorus (Ca:P) ratio in all experimental diets. Other workers have maintained a constant level of calcium at all supplemental phosphorus levels. The purpose of this study was to: (1) compare the results of two assays in which different dietary Ca:P ratios were used, and (2) observe the repeatability of results with a phosphate of reported low availability when fed at levels based on its determined phosphorus availability. Three experiments were conducted using broiler cockerels obtained from a commercial hatchery. The chicks…