THE INFLUENCE OF THE PARATHYROIDS ON BLOOD CALCIUM LEVELS AND SHELL DEPOSITION IN LAYING HENS12

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Abstract
EFFECTS of parathyroidectomy on the deposition of shell calcium in the fowl have not been determined. Previous studies have been concerned with the function of the parathyroid glands in adult male or immature ducks (1, 2) and pigeons (3, 4). Some effort was directed toward correlating changes in bone during the egg formation cycle of laying pigeons (5) and with parathyroid histology in laying hens (6). In these preceding studies, parathyroidectomy of the laying female bird, at a time preceding or during shell deposition was not performed. METHODS Adult female chickens in their 1st and 2nd year of production were individually caged in 3-deck batteries, and given water and mash, ad libitum, except when starved; then only water was allowed. These hens were crossbreeds and leghorns.