8. In addition, there are a large number of proposed additives that could be added
in the ruminant ration to lower methane emissions. Ex: yeasts, essential oils,
fibre degrading enzymes and compounds such as garlic or oregano, etc.
7 Mechanism of Methane Production by Ruminants
CH 4 is produced in the rumen of the ruminants by microbial fermentation of feed
and fodders. Rumen flora and fauna comprising of bacteria, protozoa and fungi
ferment the feed nutrients like proteins, carbohydrates (starch and plant cell wall)
into amino acids and sugars and thereafter they are converted into VFA, hydrogen
(H 2 ) and carbon dioxide (CO 2 ). VFA (acetate, propionate, butyrate, etc.) are then
absorbed and utilized by the host animal as energy source. Acetate and butyrate are
substrate for CH 4 production. So, the feed like more fibrous feeds produce more
acetate thus increases CH 4 production, but on the contrary high concentrates produce more propionate and thus reduces enteric CH 4 production.
7.1 Mitigation Strategies
There are many possibilities of mitigation of methane emission by the livestock,
e.g. providing balanced feeds, feeding less fibrous feeds, use of chemicals, ciliate
protozoa removal (defaunation), culling of unproductive animals, microbiological
and biotechnological inhibition of ruminal methanogens. All the above are having
some demerits as chemicals have toxic effects on fermentation of feed in the rumen;
providing high nutrition diet to the low producers are not economic and culling
unproductive and lower productive animals are having social and religious
restrictions. Reducing methane production can be of direct economic benefits as it
enhances the efficiency of energy utilization of the feed by the animal.
7.2 Reduction of Methane Mitigation from Ruminants
There are numerous attempts made to reduce the CH 4 production and release from
the ruminants. All are found successful to some extent and none is having without
limitations. Some are having economic barrier, some are toxic in nature after certain
limit and some are having social and religious taboo. Establishing a balance is the
main aim of all the researchers. However, some of the methods are summarized
below.
1. CH 4 mitigation is an intrinsic property of feed that vary with feed ingredients.
So, if possible, the farmers should select feeds with low methane emission
Impact of Ruminants on Global Warming: Indian and Global Context
93
in the ruminant ration to lower methane emissions. Ex: yeasts, essential oils,
fibre degrading enzymes and compounds such as garlic or oregano, etc.
7 Mechanism of Methane Production by Ruminants
CH 4 is produced in the rumen of the ruminants by microbial fermentation of feed
and fodders. Rumen flora and fauna comprising of bacteria, protozoa and fungi
ferment the feed nutrients like proteins, carbohydrates (starch and plant cell wall)
into amino acids and sugars and thereafter they are converted into VFA, hydrogen
(H 2 ) and carbon dioxide (CO 2 ). VFA (acetate, propionate, butyrate, etc.) are then
absorbed and utilized by the host animal as energy source. Acetate and butyrate are
substrate for CH 4 production. So, the feed like more fibrous feeds produce more
acetate thus increases CH 4 production, but on the contrary high concentrates produce more propionate and thus reduces enteric CH 4 production.
7.1 Mitigation Strategies
There are many possibilities of mitigation of methane emission by the livestock,
e.g. providing balanced feeds, feeding less fibrous feeds, use of chemicals, ciliate
protozoa removal (defaunation), culling of unproductive animals, microbiological
and biotechnological inhibition of ruminal methanogens. All the above are having
some demerits as chemicals have toxic effects on fermentation of feed in the rumen;
providing high nutrition diet to the low producers are not economic and culling
unproductive and lower productive animals are having social and religious
restrictions. Reducing methane production can be of direct economic benefits as it
enhances the efficiency of energy utilization of the feed by the animal.
7.2 Reduction of Methane Mitigation from Ruminants
There are numerous attempts made to reduce the CH 4 production and release from
the ruminants. All are found successful to some extent and none is having without
limitations. Some are having economic barrier, some are toxic in nature after certain
limit and some are having social and religious taboo. Establishing a balance is the
main aim of all the researchers. However, some of the methods are summarized
below.
1. CH 4 mitigation is an intrinsic property of feed that vary with feed ingredients.
So, if possible, the farmers should select feeds with low methane emission
Impact of Ruminants on Global Warming: Indian and Global Context
93