Availability of Phosphorus in Corn, Wheat and Barley for the Chick

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Abstract
Two 13-day trials involving 760 day-old chicks were conducted to evaluate the relative utilization and estimate the percentage availability of organic phosphorus in corn, hard red winter wheat, soft red winter wheat and barley containing .27, .37, .30 and .44% phosphorus, respectively. Fat and dextrose were substituted for a portion of each grain so that all diets contained an equal amount of grain phosphorus (.19%). Response criteria were survival rate, growth rate, efficiency of feed utilization and breaking strength and ash content of the tibia. In Exp. 1, chicks fed diets with corn as the grain source gained weight at a slower rate (P<.01), required more feed per unit of gain (P<.05), and had weaker tibias (P<.01) with reduced ash content (P<.01), than those fed diets containing hard wheat, soft wheat or barley, with these differences being greatest in diets with no supplemental phosphorus. No significant differences were found among chicks fed the two types of wheat or barley. Performance and bone density improved as the level of supplemental phosphorus was increased from 0 to .3% in all diets, with the degree of improvement being more pronounced in diets containing corn. In Exp. 2, three graded levels of monosodium phosphate in a semipurified diet were fed to establish a standard with which to estimate available phosphorus in the grains. Of the response criteria, tibia breaking strength provided the best linear fit (r = .99) when evaluated as a function of percentage phosphorus. Using this criterion, availability of phosphorus in corn, hard wheat, soft wheat and barley was estimated at 12, 43, 58 and 50%, respectively. The greater phosphorus availability of wheat and barley coupled with the fact that these grains contain more total phosphorus than corn should permit the use of a lower level of phosphorus supplementation when these grains are used as an energy source. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.