Calcium and Phosphorus Metabolism and Egg Shell Formation in Egyptian Birds

IN EXPERIMENTS with laying pullets Halnan (1952) noted, in White Leghorns, the storage of calcium before laying and a heavy excretion of phosphorus during laying. Common (1932, 1933, 1936, 1938, 1940) observed the storage of calcium prior to the commencement of laying and also the heavy excretion of phosphorus accompanying each egg laid. Increases in blood calcium at the time of ovulation have been noted in the domestic fowl by Hughes et al. (1927) and Russel et al. (1930). Buckner et al. (1930) and Charles and Hogben (1933) found that there were high blood calcium values during shell formation and low values when the shell was complete. Laskowski (1934) has found that the total plasma phosphorus for laying hens was very high but shows marked variation. Houchin et al. (1939) gave a phosphorus level of hen’s blood of 3.96 mg. %. Tyler and Willcox (1942) stated that calcium carbonate gives …