Weekly variations in body weight, relative body-weight gain and plasma growth hormone (GH) concentrations were determined in control and cortisone-treated (5 mg cortisone acetate/bird d) chickens between 3 and 10 weeks of age. 2. Treatment with cortisone between 3 and 5 weeks of age markedly suppressed growth but did not inhibit GH secretion. 3. After the cortisone injections were stopped these birds grew more rapidly than the controls. However, this period of "catch-up growth" was not accompanied by alterations in plasma GH concentrations.
