SUMMARY
10 ISA Brown hybrid hens, 53 weeks old, placed in individual cages, were killed by administering iv a T61 solution at 10 different times after being deprived of food. After that the digestive tracts were ligatured and segmented into 9 parts: ingluvies (ING), stomach (proventriculus and gizzard) (ST), upper duodenum (DP), lower duodenum (DD), jejunum (JEJ), upper ileum (PI), lower ileum (ID), ceca (CEC) and rectum (R). In order to determine the MRT of the dry matter in the segments of the digestive tract by the technique of continuous administration of the marker simultaneously with the total collecting of the digesta from one segment, the hens were fed with combined feed with a supplement of 0.1% Cr2O3 used as marker. The results showed that the average value of the MRT in the small intestine was of 185 minutes; the steady state of the marker is kept for 2 hours and 45 minutes after the limitation to the access to food, i.e. for the T1 – T7 killing time, but it is not valid for the hens killed during T8 (3 hours and 45 min.), T9 (5 hours and 45 min.) and T10 (7 hours and 45 min.).