Comparison of Phosphorus Availability Assay Techniques for Chicks

GENERALLY accepted methods of assaying inorganic phosphate as a source of phosphorus for chicks have usually involved at least a four-week supplemental feeding period (Gillis et al., 1948Gillis et al., 1954; Grau and Zweigart, 1953; Miller and Joukovsky, 1953; Creech et al., 1956; Gardiner et al., 1959). Ammerman et al. (1960) reported that a satisfactory assay was obtained with a ten-day feeding period which included four days of phosphorus depletion followed by six days of feeding phosphorus-supplemented diets. The objectives of this study were to: (1) compare results obtained with the ten-day depletion-repletion assay with those obtained with the standard four-week assay, (2) determine the effect of initial weight on the response of body weight and bone ash to graded levels of phosphorus, (3) determine the repeatability of the percent ash from the right and left tibia, and (4) study the feasibility of using percent beak ash for measuring phosphorus availability. EXPERIMENTAL