Effect of calcitonin on the domestic fowl

The plasma calcium response of intact and acute partially parathyroidectomized cockerels (Gallus domesticus) to the intravenous infusion of porcine thyroid calcitonin, avian ultimobranchial calcitonin, and chicken thyroid extract was determined. No hypocalcemic response was obtained in the intact cockerels with any of the agents tested. However, marked hypocalcemic responses were obtained in the partially parathyroidectomized cockerels following administration of porcine thyroid calcitonin or avian ultimobranchial calcitonin at the same dose levels (300 MRC milliunits/kg). No hypocalcemic activity was obtained with chicken thyroid extract. It is possible to speculate, from these results, that calcitonin from the ultimobranchial gland is involved in the maintenance of plasma calcium homeostasis in the chicken.