Calcium Metabolism of Pullets at the Onset of Egg Production, as Influenced by Dietary Calcium Level

THE skeleton of the laying hen has been shown by many investigators to serve as a calcium store which may be utilized for the formation of the egg shell (Simkiss, 1961). Normally, dietary calcium directly supplies only part of the calcium needed for the formation of the egg shell whereas the rest is withdrawn from the skeleton (Driggers and Comar, 1949). Maintenance of such stores is therefore important for maximum performance of the laying hen. Ten days prior to onset of egg production, calcium retention of pullets is greatly increased. This increase is commonly associated with the appearance of medullary bone is the marrow cavities of the skeleton (Simkiss, 1961). The possibility that other segments of bone, in addition to medullary bone, may also take part in this pre-laying storage of calcium has not been thoroughly investigated. Neither has it been elucidated whether the origin of calcium for the formation…