Nitsan, Z., Division of Poultry Science, Agricultural Research Organization, The Volcani Center, Rehovot, Israel
Dror, Y., Department of Agricultural Biochemistry, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
Nir, I., Department of Animal Hygiene and Poultry Science, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
Shapira, N., Department of Animal Hygiene and Poultry Science, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel

1. Force-feeding of young chicks for 15 d increased kidney arginase (EC 3·5·3·1) activity threefold. Fasting for 30 h decreased this activity by 50%. 2. Liver xanthine dehydrogenase was slightly increased after force-feeding and decreased following fasting. 3. The specific activities of two pentose-phosphate-cycle enzymes were not significantly affected by force-feeding, but glucose-6-phosphate dehydrogenase (EC 1.1.1.49) decreased following fasting. 4. The over-all secretion of digestive enzymes increased parallel to the increase in food consumption. Therefore, despite an increased absolute weight of the pancreas and intestinal chyme, specific activities were the same in the force-fed and ad lib.-fed groups, except for a higher activity in intestinal amylase. 5. Fasting did not affect the pancreatic enzymic activities. © 1974, The Nutrition Society. All rights reserved.