ENDOCRINE AND METABOLIC RESPONSES OF INTACT AND HYPOPHYSECTOMIZED TURKEY POULTS GIVEN A DAILY INJECTION OF CHICKEN GROWTH-HORMONE

Female turkey poults were hypophysectomized at 4-5 weeks of age, Begin ning at 6 weeks of age, 20 hypophysectomized and 20 intact birds recei ved a daily intramuscular injection of natural chicken growth hormone (cGH, 100 mu g/kg body weight) or vehicle for 12 days, Blood samples w ere taken from each bird just before injection and 4 hr post-injection at 6 and 12 days of treatment, Hypophysectomy reduced the growth rate of turkey poults to 75% of that of intact controls, significantly red uced carcass protein and ash percentages, and significantly lowered pl asma concentrations of GH, insulin-like growth factor-I, triiodothyron ine, thyroxine, insulin, glucose, triglycerides, and non-esterified fa tty acids, Hypophysectomy was without effect on liver GH receptor bind ing activity, but increased liver 5'-monodeiodinase activity, Daily cG H injection had no effect on the average daily gain of either hypophys ectomized or intact poults when compared to vehicle-injected controls over 12 days of treatment, Daily cGH administration increased plasma i nsulin-like growth factor-I levels in intact and hypophysectomized tur keys, and increased plasma triiodothyronine, insulin, glucose, and tri glyceride concentrations in hypophysectomized birds, but not in intact birds, Responses of young turkeys to hypophysectomy and GH replacemen t were consistent with the known metabolic role of GH in other species , but the influence of GH on growth appears to be of less importance i n poultry than in mammals.