IN-VITRO DIGESTIBILITY ASSESSMENT OF TROPICAL SHRUB LEGUMES USING RUMEN FLUID OR FECAL FLUID AS THE INOCULUM SOURCE

In vitro dry matter digestibility (IVD) studies using a modified Tille y and Terry (1963) technique were conducted using either strained catt le rumen fluid or the liquid from fresh cattle faeces as sources of in oculum. The dried leaves of 14 tropical leguminous shrubs in the gener a: Acacia, Calliandra, Gliricidia, Leucaena and Zapoteca were used as substrates together with 3 standard forages of known in vivo digestibi lity. The IVD values from using faecal fluid were linearly correlated with those obtained with rumen fluid (r=0.982; P<0.001). The faecal fl uid gave significantly (P<0.001) lower digestibility values than those obtained with rumen fluid (by 3.5 percentage units). Shrubs differed greatly (P<0.001) in IVD with a range of 22-80%. There was no signific ant interaction in IVD (P>0.05) between legume substrate and inoculum source. On the basis of these results, it was concluded that the liqui d fraction of cattle faeces provides the same precision as rumen fluid for in vitro digestion studies to rank tropical leguminous shrubs on the basis of their digestibility. In many situations, it may be easier to use faeces rather than to collect rumen fluid as an inoculum sourc e for IVD studies, especially in developing countries.