Methane (CH4) is second major gas after carbon dioxide (CO2) responsible for the warming of environment and ozone layer depletion. Although CH4 production is necessary for efficient digestion, it represents an energetic loss of up to 12% of the gross energy intake in ruminants. Methane is produced by strict anaerobes belonging to the sub-group of the Archaea domain. The past decade has shown a lot of interest in the use of plant extracts to mitigate methane production in ruminants. Addition of plant essential oils, can limit the growth of the micro-organisms participating in methane formation in the rumen, thus resulting in the reduction of its production. Reduction of methane production in the rumen ecosystem is possible to achieve with the use of plantsaponins. Tannins have been found to be toxic for many of the rumen microbes, especially ciliate protozoa, fibre degrading microbes and methanogenic bacteria as a result of this methanogenesis in the rumen is reduced. 

An in vitro study evaluated the anti-methanogenic potentiality of aqueous and alcoholic plant extract mixture of ajwainseed and soapnut berries under different roughage and concentrate ratio-based diets in a 3x3 factorial design. Dried and milled plant mixture was extracted (10 g/100 ml) in three solvents, viz, water (Control), ethanol (95 %), and methanol (98 %). Substrate (200 mg) prepared by mixing wheat straw and concentrate mixture at the ratio of 30:70, 50:50 and 70:30 was taken in glass syringes (six per treatment) and incubation medium (30 ml) dispensed anaerobically. Aqueous, ethanol and methanol plant extract (0.5 ml) were taken in three dietary treatments of groups I, II, and III respectively. All the syringes were incubated at 39°C for a running duration of 24 hours and total gas production was calculated. Hundred ml of emitted gas was injected into gas chromatograph equipped with flame ionization detector for methane estimation. In vitro true digestibility of diet and ammonia nitrogen content of fermented medium were determined. Experimental data generated were analysed by adopting factorial ANOVA procedures. Results revealed that ethanol plant extract mixture had significantly (P<0.01) reduced the in vitro total gas and methane production by suppressing the true dietary digestibility of high roughage to low concentrate (70:30) based diet.

In vitro digestibility study was conducted to determine the effectsof supplementing fractionated Refined,Bleached and Deodorized Palm Stearin(RBDPST) on ruminal digestion. Fractionated RBDPST was soaked in incubation medium consisting of distilled water, buffer solution, trace element solution, micro and macro mineral solution, as well as rumen liquor that was collected from slaughtered cattle. This experiment was conducted at 39°C with an incubation period of 24 hours. Dried napier grass was used as control treatment. Gas producedwas recorded and collected to measure the methane gas produced. Methane gas produced from fractionated RBDPST was found to be relatively lower than control. This indicates that fractionated RBDPST had the ability to function as rumen bypass fat as it was not fully digested in the rumen.