The Mean Retention Times of Digesta Markers in the Gut of the Tammar, Macropus Eugenii.

Abstract

The average mean retention times of a solute marker (51chromium complex of EDTA) were 15.7 and 11.3 h, and of a particle marker (tris (1,10-phenanthroline) ruthenium (II) chloride labelled with 103Ru) 29.3 and 19.1 h, in tammar wallabies given, respectively, one meal of lucerne hay pellets daily or a similar ration fed continuously. Much more of the solute marker was excreted in the urine of those given one meal daily. The marker concentration curves showed irregularities that could be interpreted as due to 2 main processes. One was passage of small amounts of digesta through the gut much more rapidly than the bulk. The second was temporary sequestration and subsequent release of small amounts of digesta, at times in or before the major mixing compartment, presumably the stomach, at times in a tubular compartment after all substantial mixing compartments, with subsequent release. Attempts at kinetic analysis of the marker concentration curves were unsuccessful. Some were killed after 3 days' continuous feeding on labelled food. The amounts of marker in the digesta suggested that the stomach was the major site of delay in the passage of the particle marker, accounting for about two-thirds of the total retention time, and was also the major site of separation of the solute and particle markers. There was no evidence for any other major mixing compartment.