Discussion in this paper is confined to consideration of methods that have been developed for collecting and sampling digesta from ruminants fitted with reentrant intestinal cannulas. The considerable volume of literature relating to animals fitted with simple cannulas is not included ; marker dilution techniques are used to calculate flow through the intestines in these preparations and they are reviewed in this symposium (MacRae, 1974). The use of indigestable markers to estimate depression

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... flovi7 of digesta during short-term periods of total collection from re-entrant cannulas is, however, examined ; an advantage of automated systems is the ability to continue collections for extended periods of time and hence to provide a basis for evaluation of the accuracy of marker-corrected flow in short-term manual collections.