Three experiments were conducted to determine the fate of condensed tannins (CT) during digestion in sheep. CT were measured as extractable, protein-bound and fibre-bound fractions using the butanol-HC1 procedure. In Expt 1, purified CT were added to digesta from different parts of the digestive tract obtained from a pasture-fed sheep. Recoveries of CT after 0 and 4 h of anaerobic incubation at 39" averaged: rumen 78-9 and 575 % ; abomasum 50.9 and 490 YO ; duodenum 64.4 and 46.0 YO and ileum 43.4 and 38.8 %. In Expt 2, ['4C]CT was given per ubomusum over a 6 5 h period at 15 min intervals to a sheep previously fed on Lotus peduncuZutus (which contains CT). The sheep was killed at the end of the period and 92.4 % of the label was recovered. Virtually all of the label was in the digesta, and none was detected in the blood, so that the CT-carbon appeared not to be absorbed from the small intestine. In Expt 3, rumen, abomasal and ileal digesta and faeces samples from sheep fed on Lotus pedunculutus were analysed for CT and CT flow along the digestive tract calculated from reference to indigestible markers. Values were low in all digesta samples, indicating disappearance of CT across the rumen and small intestine, and CT recovery in faeces was only about 15% of intake. However, the I4C results from Expt 2 suggested that little if any CT-carbon was absorbed and the low recoveries in Expt 1 are considered to be a consequence of either conformational changes to the CT molecule such that it is no longer detectable by colorimetric methods, an inability of the analytical method to release bound CT for the butanol-HC1 assay, or interference from other digesta constituents. It is concluded that the butanol-HC1 method of CT analysis is appropriate for quantifying CT in herbages but not in digesta or faeces, and that a substantial part of CT released during protein digestion in the small intestine may not be detectable by normal CT analytical methods.['4C]Condensed tannin: Digesta tannins : Tannin digestion Condensed tannins (CT) are polyphenolic compounds occurring in a wide range of plants eaten by ruminants (Jones et al. Sarkar et al. 1976; Terrill et al. 1992b). They may be either beneficial or detrimental to the animals' nutrition depending on concentration in the forage, astringency and pH-dependent protein-binding characteristics. The concentration of CT may be as high as 200g/kg plant dry matter (DM) but most of the herbages ingested by ruminants contain 2&100gCT/kg DM (Terrill et al. 1992b). Evaluation of the role played by CT in ruminant nutrition has been hindered by analytical difficulties, especially the quantification of CT in digesta and faecal material. There are two commonly used procedures for CT quantification; the vanillin-HC1 method (Broadhurst & Jones, 1978) and the n-butanol-HC1 method (Bate-Smith 1973; Porter et al. 1986). Both methods are semi-quantitative (Mangan, 1988) so that considerable variation can exist

1978). Groups are usually defined a priori by some criterion external to the set of variables measured, e.g., rootstocks (Cruz-Castillo et al., 1992), carbohydrate status (Prins et al., 1990), supermarkets selling flowers (Behe et al., 1992), tree species (Majer et al., 1992), or swede (Brassica napus L., Napobrassica Group) cultivars (Cole and Phelps, 1979). The objective of this paper is to present a description of CDA and demonstrate its applicability and potential in horticultural research.

Both target-site and non-target-site mechanisms of glyphosate resistance were found in the perennial ryegrass population with 25-fold resistance, whereas only the non-target-site mechanism of resistance was found in the population with sevenfold resistance. This is the first study of the mechanism of glyphosate resistance in perennial ryegrass.

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