The polyphenol concentration in various tree fodders has been assayed by the gas production technique using rumen fluid inoculum either by fermentation of whole samples +/- a polyphenol adsorbent (Khazaal et al., 1994) or simply by the reduction of gas production caused by acetone extracts of the fodders (Wood and Plumb, 1995). Successful replacement of rumen fluid as a source of anaerobic bacteria by faeces from ruminant animals has been reported both for two-stage Tilley and Terry dry-matter digestibility (DMD) (El Shaer et al., 1987) and for the gas production technique (Davies, 1991). The use of faeces based inoculum +/- polyphenol adsorbents was therefore tested and optimized for fallen paulownia and poplar leaves using the gas production technique (the trees were commercial hybrids of Paulownia and Populus species respectively). A series of trials was carried out to: develop the use of preliminary incubation of the faeces inoculum; optimize the adsorbent type, molecular weight (MW) and quantity; optimize the faeces concentration in the inoculum and the use of glucose as a pre-incubation stimulant; and evaluate the use of differences in Tl /2 for gas production and end DMD +/- adsorbent to assess the effect of anti-nutritive compounds (ANCs) on the relative rate and extent of fermentation.

All trials were carried out using 100 ml plastic vaccine flexibottles as containers maintained at 39°C in water baths. Gas was manually extracted with disposable syringes, generally at 3, 6, 9,12,15,18, 21, 24, 30, 36, 42, 48, 60, 72 h and bottles were well shaken at these times.