1. Effects of food restriction on growth rate and relative growth rates of supply organs (liver, heart, lungs and kidneys, digestive tract) and demand organs (breast, back, thighs, abdominal fat) of broiler chickens were studied. 2. Birds were restricted in intake to 50% (group FI 50) or 75% (group FI 75) of ad libitum from 5 to 11 d of age; all birds were fed ad libitum from 12 to 39 d of age. 3. Relative growth rates from 12 to 39 d of age of group FI 50 were higher (P < 0.05) than group FI 75 and control group. 4. No significant differences in food conversion ratio, carcase fat and abdominal fat between groups were observed. 5. At 12 d of age, relative weight of the empty digestive tract of group FI 50 was higher (P < 0.05) than that of the control group and group FI 75. 6. The increased weight of the empty digestive tract may have contributed to the ability of the chickens to achieve compensatory growth after the restriction period.

1. Two experiments were performed on broiler chicks to determine the effect of either quantitative feed restriction (QFR) from 5 to 11 d of age or meal-feeding (MF) from d 5 to 17 on development of activity of enzymes associated with protein digestion. 2. Proteolytic activity of the proventriculus was reduced by QFR but unaffected by MF. 3. General proteolytic and carboxypeptidase A activities of the pancreas were reduced by QFR and MF. 4. Amino- and dipeptidase activities of the small intestine were increased by QFR. Dipeptidase activity was unaffected by MF. 5. Nitrogen retention of QFR chicks was lower immediately following feed restriction but not in the 2 weeks following return to ad libitum access to feed. 6. Feeding regimen alters functional development of the enzymes of protein digestion and may therefore influence growth rate of broilers.