Disappearance of growth hormone from blood (plasma) was studied in young broiler chickens
in two experiments: a) following single injection of GH (50 μg or 250 μg/kg) to anesthetized
chicks; b) injection of GH (50 μg/kg) (under anesthesia) to two lines of broilers
selected for either rapid growth or feed efficiency. Clearance of GH never followed
a single negative exponential curve. Characterization of the disappearance by a single
metabolic clearance rate and half-life time were found to be inaccurate and inappropriate
on methodological grounds. High doses of hormone might disturb receptor or catabolism
equilibria and result in aberrant values of MCR which could probably be because of
the very dynamic nature of the GH clearance system, which appeared to be influenced
by dose, line (or genetics of the animal) and by some indices of clearance. Therefore,
physiological significance of such data must be interpreted carefully.
GH-Metabolic Clearance Rate - Broilers
