Effect of leaf extracts on in vitro fermentation of feed and methanogenesis with rumen liquor of buffalo

The leaves of Coriandrum sativum (coriander), Quercus incana (oak), Populus deltoides (poplar), Ocimum sanctum (tulsi) and Moringa oleifera (drumstick) extracted in 3 solvents (ethanol, methanol and water) at 3 levels (0, 0.25 and 0.5 ml/30 ml of incubation medium) were tested in 6x3x3 factorial design for their effect on fermentation of feed and methanogenesis in in vitro gas production test. The extracts of C. sativum and M. oleifra enhanced gas production significantly as compared to control and other leaf extracts. Methanol extract of the leaves of R. deltoides caused a significant depression in methanogenesis, whereas, none of the other leaf extracts had any effect. The specific activities of carboxymethylcellulase, xylanase and acetyl esterase were increased by addition of leaf extracts in the medium. The concentration of total volatile fatty acids was similar among the extracts of 5 leaves, but there was significant decrease in acetate to propionate ratio on inclusion of 0.5 ml methanol extract of P. deltoides in the medium. None of the 5 leaf extracts had any effect on in vitro degradability of dry matter or organic matter. The numbers of total protozoa, large and small spirotrichs and holotrichs were not affected by any of the leaf extracts. The results indicated that the methanol extract of R. deltoides leaves inhibited rumen methanogenesis without. adversely affecting other fermentation characteristics.