Effect of pulsatile or continuous administration of pituitary-derived chicken growth hormone (p-cGH) on lipid metabolism in broiler pullets.

1. The effects of pulsatile and continuous intravenous administration of exogenous, pituitary-derived chicken growth hormone (p-cGH) on lipid metabolism and endocrine/metabolite levels of broiler-strain pullets were studied. 2. Eight-week-old pullets were administered p-cGH or vehicle over a 10 min period every 90 min for 7 days. 3. Pullets were also administered the same daily amount (123 micrograms/kg of body weight/day) continuously for 7 days. 4. Feed intake, body weight gain, in vitro lipogenesis and hepatic enzyme activities were determined with certain hormones identified with the control of growth. 5. Pulsatile p-cGH administration for 7 days lacked effect on weight gain, feed efficiency, muscle or bone development. 6. Abdominal fat pad size was decreased (P less than 0.05) by pulsatile but not continuous administration of p-cGH. Pulsatile p-cGH administration also decreased (P less than 0.05) in vitro lipogenesis. Liver malic enzyme and isocitrate dehydrogenase activities were increased (P less than 0.05) by pulsatile but not continuous administration of p-cGH. In contrast, glutamic oxaloacetic transaminase activity was increased by a continuous infusion of p-cGH. 7. Plasma concentrations of T4 corticosterone and triglycerides were decreased (P less than 0.05) by a pulsatile but not a constant infusion of p-cGH. 8. Plasma T3 and GH were increased (P less than 0.05) by pulsatile p-cGH compared to both a continuous infusion of p-cGH and the saline controls. 9. This study is the first to prove that in the broiler chicken, the pattern of exogenous p-cGH administration is a factor influencing in vitro responses to the hormone.