Changes in Prolactin Content of Fowl Pituitary during Broody Periods and Some Experiments on the Induction of Broodiness

THE induction of broodiness in laying fowl by the injection of prolactin was reported by Riddle, Bates and Lahr (1935). Burrows and Byerly (1936) showed that pituitaries from broody hens had much greater prolactin content than those from laying hens. They also suggested that the pituitaries of hens just becoming broody had more prolactin content than those of hens nearly over their broody period. Saeki and Tanabe (1954) showed that, as the results of the direct comparison of each pair of pituitaries, as judged by the local responses in both the crop-sacs of the same pigeon, the pituitary of the broody hen maintained a relatively high prolactin content as long as her nesting (incubating eggs) lasted as compared with that of the pituitary of the laying hen, and its content began to drop to the same level as that of the laying hen when she hatched her eggs and shifted …