In young calves receiving a small i.v. dose of Ca to stimulate calcitonin release, i.v. infusion of somatostatin did not significantly modify the jugular venous plasma calcitonin levels measured by radioimmunoassay, using a porcine system which cross-reacts with bovine calcitonin. In piglets, i.v. infusion of somatostatin also did not change the jugular venous plasma calcitonin concentration.