COMPARATIVE GROWTH AND DEVELOPMENT OF THE DIGESTIVE ORGANS AND OF SOME ENZYMES IN BROILER AND EGG TYPE CHICKS AFTER HATCHING

1. Body weight, the weight of digestive organs and activities of some digestive enzymes were determined from hatching to 14 d of age in meat- and egg-type chickens. 2. Relative daily food intake and growth rate were much higher in meat- than in egg-type chickens. Relative daily food intake peaked at 30% of body weight at 3 d of age in meat-type, and at 20% of body weight at 6 d of age in egg-type chickens and then decreased gradually. The corresponding values for growth rate were 20 and 14%. 3. Allometric growth of the small intestine, intestinal contents and liver was greater in meat-type chickens, but the growth of the pancreas attained a higher value in the egg-type birds. Diminution of the vitelline residue was similar in the two breeds. 4. Pancreatic digestive enzyme activities were similar between stocks, but activities in the small intestinal contents were lower in meat-type chickens. 5. The secretion of digestive enzymes in the newly-hatched meat-type chicken could be a limiting factor in digestion and, consequently, in food intake and growth.