Effect of plants containing secondary metabolites on in vitro methanogenesis, enzyme profile and fermentation of feed with rumen liquor of buffalo

The effect of seed pulp of Terminalia chebula (harad), leaves of Populus deltoides (poplar) and bulb of Allium sativum (garlic) and their mixture (in equal proportion) were tested at four different levels of replacement (0, 10, 20 and 30 mg per 200 mg substrate, consisting of wheat straw and concentrate mixture in equal ratio) for in vitro methane production, enzymes profile and rumen fermentation characteristics in in vitro gas production test. The gas production (ml/g DM) was significantly higher (P<0.05) with poplar, garlic and the mixture of three as compared to harad alone or control. Methane production (ml/g DM) was significantly reduced (P<0.05) on adding harad, poplar and garlic separately in the incubation medium. Harad at the level of 20 and 30 mg reduced 18% and 32% methane production in comparison to control containing 0 mg additive. There was 20.6% and 14.2% decrease in methane production when 10 mg poplar and 30 mg garlic were added in 30 ml incubation medium. Activities of carboxymethylcellulase, xylanase and acetylesterase were similar (P>0.05) among the treatments and the levels. There was no effect (P>0.05) of any of the additives on TVFA at any level tested. There was also no difference in molar proportion of acetate, butyrate and acetate to propionate ratio as compared to control and among treatments. Holotrichs, small and large entodiniomorphids as well as total protozoa were also not affected with (P>0.05) treatments and levels tested. The results indicated that all the plants tested in this experiment inhibited methanogenesis without adversely affecting other rumen characteristics.