TEMPORAL SECRETORY PATTERNS OF GROWTH-HORMONE IN THE DANISH BROILER LINES SELECTED FOR HIGH BODY-WEIGHT OR FOR IMPROVED FOOD EFFICIENCY

Plasma growth hormone (GH) secretory profiles of S-week-old male and f emale broiler chickens selected for high body weight at 42 days of age (GL line) or for improved food efficiency between 18 and 39 days of a ge (FCR line) were compared. A pulsatile GH secretory pattern was stil l present for all the 8-week-old chickens examined. Overall mean GH le vels, and to a lesser extent GH baseline and GH amplitude values, were higher for FCR chickens compared with GL chickens. Mean GH concentrat ions, baseline and amplitudes were slightly, but not significantly, su perior in males. Length and frequency of pulses were not influenced by line or sex. In view of the current knowledge on age- and sex-related changes in pulsatile GH secretion, it is argued that the line and sex differences would have been more pronounced in younger chickens. Base d on this, the hypothesis that the amplitude of the pulsatile GH relea se is related to protein conversion efficiency and protein deposition rather than to average body weight gain is corroborated.