Early and temporary quantitative food restriction of broiler chickens. 2. Effects on allometric growth and growth hormone secretion.

1. An experiment was conducted with male broiler chickens to investigate the effect of different early food restriction programmes on proportional weights and allometric growth coefficients of carcase parts and on pulsatile growth hormone secretion. 2. At 4 d of age the animals were restricted to 80% or 90% of the ad libitum intake for 4 d or 80% for 8 d. When the restriction was finished, all birds received ad libitum food again. 3. On d 1, 8, 11, 14, 21, 28, 35 and 42, from each group 8 birds were weighed, stunned and killed and the weights of the stomachs, liver, heart, sternum, right thigh, right drumstick, breast and abdominal fat pad were determined. On d 29, 30, 31, 32 serial blood samples of 2 birds from each group were taken to determine the plasma growth hormone (GH) content. 4. Only the most severe restriction resulted in a tendency for the stomachs to mature earlier and the thighs to mature later. No other significant effect on the allometric coefficients could be observed. 5. It is concluded that during the restriction the birds give priority to the development of the supply organs such as the stomach, which are more important during early development at the expense of the demand tissues like breast and thigh. 6. No significant differences concerning the GH secretory parameters could be observed.