INORGANIC PHOSPHORUS, ORGANIC PHOSPHORUS, AND INORGANIC CALCIUM IN BLOOD PLASMA FROM TWO BREEDS OF CHICKENS FED VARIOUS LEVELS OF DIETARY CALCIUM AND PHOSPHORUS

Male crossbred broiler-type and Single Comb White Leghorn (SCWL) chickens were fed graded levels of dietary calcium (0.0, 0.3, 0.6, 0.9, 1.2, and 1.5% added) and phosphorus (0.18 and 0.36% added) from hatching to 4 wk of age. Inorganic phosphorus (PPi), inorganic calcium (PCai), and organic phosphorus (PPo) were determined on blood plasma obtained when the chickens were 4 wk old. PCaiwas influenced by breed, phosphorus, calcium, breed × calcium, and phosphorus × calcium. PPiwas influenced by the dietary level of phosphorus and calcium and a significant (P < 0.01) phosphorus × calcium interaction occurred. The dietary calcium level had a significant (P < 0.05) effect on PPoand there was a highly significant (P < 0.01) breed × calcium interaction. Regression coefficients were determined for PCaion PPi, PCaion PPo, and PPion PPousing individual data from the 24 groups and by dietary calcium levels (six groups). Few significant regressions were obtained using the individual data from the 24 groups or the data pooled by calcium levels (six groups). The most important significant regression appeared to be between PCaiand PPiat the lowest dietary calcium level.