Some biological activities of recombinant DNA-derived growth hormone on plasma metabolite concentrations in domestic fowl.

The biological activity of recombinant-DNA-derived chicken growth hormone (rcGH) has been examined in young broiler cockerels, by determining its effects on plasma concentrations of glucose, free fatty acids and alpha-amino nitrogen. A single injection of rcGH increased plasma glucose, which remained high for several hours, whereas daily treatment with rcGH for 1 week had no effect on basal plasma glucose concentrations but blunted the glucose response to a further rcGH challenge. Plasma free fatty acids were also promptly increased following acute rcGH treatment, and chronic exposure to rcGH again attenuated this response. The effects of rcGH on plasma alpha-amino nitrogen were more variable. The stress of repeated blood sampling tended to reduce alpha-amino nitrogen, and after rcGH, an increase relative to vehicle-injected controls was seen in both acute and chronically-treated birds. These data suggest that rcGH has both hyperglycaemic and lipolytic activity in chickens, and may also increase amino acid availability.