Measurement of the rate of flow of dry matter in digesta passing through the duodenum of sheep.

1. A total of seven sheep fitted with re-entrant cannulas in the proximal duodenum were used in three experiments to measure the passage of dry matter (DM) in duodenal digesta. 2. Fifty-three 24 h measurements and ten 48 h measurements of DM flow were made in Expt 1. Coefficient of variation (CV) of these measurements was 22-1% which was similar to variability reported for chromic oxide 'corrected' flows and for an estimate of day-to-day variation. DM flow on day 1 was 103-2% (SE = 8-94) of flow on day 2 in 48 h measurements. 3. In two 3 X 3 Latin-square design experiments, duodenal DM flow was measured continuously over 72 h and on days 1, 2 and 3 DM flow was 100-4, 102-6 and 96-9% (SE = 5-82) of mean flow (Expt 2) and 95-8, 101-2 and 103-0% (SE = 6-70) of mean flow (Expt 3) respectively. 4. It was concluded that no depression in duodenal DM flow occurred during the first 24 h of collection in these experiments and that the variability of repeated 24 h measurements of flow was within day-to-day variation.