UPTAKE CAPACITY IN-VITRO FOR GLUCOSE AND METHIONINE AND IN-SITU FOR OLEIC-ACID IN THE PROXIMAL SMALL-INTESTINE OF POSTHATCH CHICKS

The uptake capacity of the duodenum and jejunum was determined in vitr o for glucose and methionine using C-14-inulin as an unabsorbed refere nce substance in posthatch chicks. Fatty acid uptake in situ was also determined in the duodenum. Methionine uptake capacity increased in bo th duodenum and jejunum between hatch and 7 d and was constant between 7 and 14 d. Calculation of apparent Michaelis constant (K-t) for both substrates indicated little change with age and thus the amount of ca rrier in the intestine may be increasing. Uptake capacity of the duode num for glucose increased between hatch and 7 d of age but no changes were found between 7 and 14 d. In the jejunum, uptake capacity was con stant from hatch to 14 d of age. In situ uptake of oleic acid in the d uodenum did not change between hatch and 14 d of age. These results su ggest that intestinal uptake capacity changes little after 7 d of age, and thus feed intake may be the major factor controlling nutrient upt ake in chicks.