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.

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.

This study was conducted to investigate methane production potential of feed ingredients to develop a database on methane production. Feed ingredients such as cereal grains, cereal by-products and protein supplements were tested for methane production potential using in vitro gas production technique. In vitro true digestibility (IVTD) of cereal grains ranged from 60.1 to 96.7% and oats grain (76.2%) and distiller’s grain (60.1%) had lower (P<0.05) values than other cereal grains. Among the cereal by-products, wheat bran showed highest (P<0.05) IVTD (74.9%) than rice bran (42.7%). IVTD of cottonseed oil cake, black gram and sunflower oil cake was lower (P<0.05) than other protein supplements. Methane production potential of cereal grains at half life (t1/2) ranged from 0.66 to 2.85 ml/100 mg truly digested substrate and the difference was significant (P<0.05), however, maize grain, sorghum grain, bajra and broken rice did not vary among themselves. Average methane production potential of cereal by-products at half life (t1/2) and 24 hrs was 1.27 and 1.81 ml/100 mg truly digested substrate, respectively. Average methane production potential of protein supplements at half life (t1/2) and 24 hrs was 1.39 and 1.75ml/100 mg of truly digested substrate, respectively and the difference was statistically significant (P<0.05). Maximum (P<0.05) methane production potential at half life (t1/2) was recorded for black gram (4.07 ml/100 mg truly digested substrate). Lowest methane production potential both at half life (t1/2) and 24 hrs were recorded in fish meal and spirulina. It can be concluded that among cereal grains, methane production potential was higher (P<0.05) in oats grain at half life (t1/2) and all the cereal grains had similar methane production potential at 24 hrs. Among cereal by-products, wheat bran had higher (P<0.05) methane production potential both at half life (t1/2) and 24 hrs. Among protein supplements, black gram had significantly (P<0.05) higher methane production potential at half life (t1/2) and horse gram had significantly (P<0.05) higher methane production potential at 24 hrs. 

An experiment was conducted to study the effect of supplementing plant metabolites like tannin and saponin through Acacia nilotica plant extract on methane mitigation and rumen fermentation characteristics for dairy cattle by in vitro gas production technique (IVGPT) in forage based diet. A highly significant (P<0.01) reduction of methane was observed in Acacia nilotica plant extract supplemented groups than their respective controls. The significant (P<0.05) reduction of methane (ml) per 100 mg of truly digested substrate was found in 0.75 ml of Acacia nilotica extract supplemented group than other treatment groups after eliminating the errorinduced by the extractant. The rumen fermentation characteristics viz. ammonia nitrogen, in vitro true dry matter digestibility (IVTDMD), bacterial and protozoal population was significantly decreased in 0.75 ml and 1.0 ml Acacia nilotica plant extract added groups. The total volatile fatty acids (TVFA) and propionic acid were significantly (P<0.05) increased and acetic acid and acetate to propionate (A/P) ratio were significantly (P<0.05) decreased in 0.75 ml and 1.0 ml Acacia nilotica plant extract added groups than their respective control groups. It was concluded that the methane (ml) per 100 mg of truly digested substrate was significantly decreased at the inclusion level of 3.09 % of tannin and 2.34 % saponin through Acacia nilotica plant extract supplemented group than control.

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.