Fluctuations of Calcium and Inorganic Phosphorus in the Blood of the Laying Hen During the Cycle of One Egg

Abstract

THE calcium content in the blood of the laying hen during the approximately 26 hours of a single egg cycle has recently been studied by several investigators with a variety of results. Charles and Hogben (1933) reported that the presence of an egg in the oviduct is accompanied by a transitory rise in blood calcium. However, their results are unreliable because they sacrificed the hen to determine the position and condition of the egg and thus had to use a different hen for each determination. It has been demonstrated by various workers that the calcium level in the blood of laying hens varies greatly among the individual hens so, unless the same hen is used for each set of bleedings, the results obtained are not comparable. Knowles, Hart, and Halpin (1935) used the same hen for each series of bleedings and obtained results in opposition to those of Charles and . . .