Adaptation of light-bodied chicks to meal feeding: gastrointestinal tract and pancreatic enzymes.

1. Two-week old male chicks of a light-bodied strain were either fed ad libitum or given one (1M) or two (2M) 2-h meals per day. A fourth group was pair-fed (P1M) the amount of food which had been consumed by the 1M group on the preceding day. 2. Compared with ad libitum-fed counterparts, a marked increase in the relative weight of the storage organs (crop and gizzard) was observed in the meal-fed birds. The relative weight of the intestine was not affected by meal feeding but the ileal wall became thinner. 3. After food deprivation for 14 or 22 h, respectively, for the ad libitum and the meal-fed chicks, the weights of contents in the gastrointestinal tract (GIT) segments did not differ between treatments except for those of the gizzard and caecum. Food restoration resulted in an increase in the contents of the GIT of meal-fed chicks. The increments in the crop and gizzard contents were related to the severity of food restriction. The contents of the intestinal segments were quite similar in all treatments. 4. The activities of the digestive enzymes in the pancreas, expressed as units/g pancreas or units/kg body weight, were not significantly affected by feeding regime. In the small intestine of the meal-fed birds, marked increases in specific (units/g content) and relative (units/kg body weight) activities were observed of amylase and chymotrypsin when compared with their ad libitum-fed counterparts. The effect of meal feeding on trypsin activities was less pronounced.