role of livestock in methane production and mitigation strategies for reduction of methane production

1. Ruminant contribution to methane
and mitigation strategies
Dr. Nazir Ahmad Mir
Ph.D scholar (Animal Physiology)
NDRI Karnal Haryana,India
Credit Seminar
on

2. Introduction
 Methane is classified as a trace gas and is estimated to have a total global
concentration of 1774 ± 1.8 parts per billion (ppb), with a total increase of 11 ppb
since 1998
(Forster et al ., 2007)
 Methane is an especially potent trace gas due to its global warming potential, 25
times that of carbon dioxide, and its 12-year atmospheric lifetime; it is the second
largest anthropogenic greenhouse gas, behind carbon dioxide
(IPCC 2001)
 Globally, 50–60% of methane emissions are from the agricultural sector,
specifically from livestock production operations; the principal source of methane
is from ruminant animals
(Ellis et al., 2007)

3. Cont…
 Domesticated ruminants, such as cattle, sheep, and goats produce
as much as 86 million metric tonnes (Tg) of methane per year.
(McMichael et al ., 2007)
 On average the amount of CH4 produced by a sheep is about 30
litres each day and a dairy cow up to almost 200 litres per day.
(GHGMP, 2005)

4. What are methanogens?
• Use H2 to reduce CO2 to methane (CH4)
• Usually coccoid or rod-shaped
• Obligate anaerobes
• Although they can’t function with O2, they can sustain oxygen
stresses for prolonged times
• Over 50 species have been identified
String of methanogen bacteria

5. Where are methanogens found?
 Wetlands, where generated
methane is called marsh gas
 Guts of animals like
ruminants (cattle, sheep,
goats) and humans
 Methanogens might be
responsible for CH4 found in
the atmosphere of Mars

6. ANIMALS
90
LANDFILLS +
WASTEWATER
50
GAS + OIL
60
COAL
30
RICE 40
TERMITES
20
WETLANDS
180
BIOMASS BURNING
+ BIOFUEL
30
GLOBAL METHANE
SOURCES
A.M. Fiore

7. Methane production in the rumen
Hexose
[2H]
Oxaloacetate
Malate
Pyruvate
Formate
Acetyl CoA
Propionate Succinate
Fumarate
Lactate
Butyrate
Acetate
Acryl CoA
CH4
[2H]
[2H]
CO2
CO2
CO2
CO2
Cellulose
Hemicellulose
Starch
[2H]
[2H]
[2H]
[2H]
CO2
[2H]
57.5 C6H12O6 →
65Ac+20Pr+15Bu+35CH4+60C
O2+25H2O
General metabolic pathways in the rumen

8. Hexose
[2H]
Oxaloacetate
Malate
Pyruvate
Formate
Acetyl CoA
Propionate Succinate
Fumarate
Lactate
Butyrate
Acetate
Acryl CoA
CH4
[2H]
[2H]
CO2
CO2
CO2
CO2
Cellulose
Hemicellulose
Starch
[2H]
[2H]
[2H]
[2H]
CO2
[2H]
Cont…

9. A. 4H2 + CO2 ⇨ CH4 + 2H2O (major pathway)
B. 4HCO2H ⇨ CH4 + 3CO2 + 2H2O (15〜20 %)
C. 4 CH3OH ⇨ 3CH4 + CO2 + 2H2O (minor pathway)
D. CH3CO2H ⇨ CH4 + CO2 (minor pathway)
Substrates for Methanogens in the rumen
Methanobacteriaceae: H2 / CO2, formate
Methanobacterium formicicum, Methanobrevibacter ruminantium,
Methanobrevibacter smithii, Methanobrevibacter curvatus,
Methnosphaera stadtmanae
Methanomicrobiaceae: H2 / CO2, formate (not utilize acetate)
Methanomicrobium mobile
Methanosarcinaceae: acetate, methanol, metylamines → CH4
Methanosarcina mazei, Methanosarcina barkeri
Methane-producing pathways in the rumen

10. Methane production in the rumen
 The methane is produced through the integrated activities of
different microbial species, with the final step carried out by
methanogenic bacteria (Moss et al., 2000)
 Methane synthesis is regarded as relationship between
hydrogen-producing microbes and hydrogen consuming
methanogens.
 The hydrogen-producing microbes and their co-association
with methanogens allows efficient removal of hydrogen that
reduces CO2 to CH4, which facilitates continuous fiber
degradation.

11. 1 Hexose
2 Pyruvate
2 acetyl CoA
2 Acetate 1 Butyrate
2 Lactate
2 Propionate + Acetate2 Propionate
ATP 4 3 4 3
NADH or
FADH2
4 2 0 0
O2 0 0 1 0
Randomising pathway Direct Reductive pathway
When methane reduction is attempted, it is
necessary to consider alternative hydrogen
sinks for methanogenesis

12. ( Kobayashi, 2010)
Hydrogen-consuming pathways recognized in
the rumen

13. NO3
-
NO2
-
NH4
+
fumarate reduction
Strategies for reduction of methane emissions
Cellulose
Hemicellulose
Starch
glucose
pyruvate
formate
[2H]
CO2 H2
reductive acetate formation
acetic acid
4[2H]
2CO2
fumarate
succinate
propionic acid
methane formation
CO2
CH4
4H2
[2H]
[2H]: reducing
equivalent (2e- + 2H+)
sulfate reduction
H2S
SO4
2-
nitrate/nitrite reduction
3[2H]
4[2H]
butyric
acid
[2H]
[2H][2H]

14. fumarate reduction
Strategies for reduction of methane
emissions from the rumen
Cellulose
Hemicellulose
Starch
[2H]
reductive acetate formation
methane formation CH4
sulfate reduction
nitrate/nitrite reduction
Hydrogen-producing reactions
Types of feed
Hydrogen-consuming reactions
by bacteria, protozoa, fungi
Materials for
rumen fermentation
Compounds (Feed additives)
Compounds for modification of rumen fermentation

15. Grain-based diets
Types of feed
Hexose
[2H]
Oxaloacetate
Malate
Pyruvate
Formate
Acetyl CoA
Propionate
Succinate
Fumarate
Lactate
Butyrate
Acetate (oxidative acetogenesis)
Acryl CoA
CH4
[2H]
[2H]
CO2
CO2
CO2
CO2
Cellulose
Hemicellulose
Starch
[2H]
[2H]
[2H]
[2H]
CO2
[2H]
hydrogen-producing reactionshydrogen-consuming
reactions
As results of grain-based diets;
pH
acetate / propionate (A/P) ratio
starch-digesting
bacteria
lactate-utilizing
bacteria

16. Defanautation
Vaccination
FatsEnzymesDicarboxyllic acids
Reductive acetogenesisPlant secondary
compounds
Animal breeding
Dietary
supplements
Forage quality
Mitigation Strategies
Rumen manipulationDiet manipulationAnimal manipulation

17. Dietary manipulation
 Improving forage quality, either through feeding forages with lower fibre
and higher soluble carbohydrates, changing from C4 to C3 grasses, or even
grazing less mature pastures can reduce CH4 production
(Beauchemin et al., 2008)
 Increasing forage quality combined with the management of stocking rates
and rotational grazing strategies have been demonstrated to reduce enteric
methane emissions ( FAO,2010)
 Methanogenesis tends to be lower when forages are ensiled than when
they are dried and when they are finely ground or pelleted than when
coarsely chopped (Martin et al., 2010)
 Forage rich diets result in acetic type fermentation, with an increase of
methane production compared to propionic type fermentation which, on
the other hand, is stimulated by concentrates (Kingeston et al., 2010)

18.  Methane energy loss of 6 to 7% of gross energy intake was observed when
forages were fed at the maintenance plane of nutrition and this reduced to 2-
3% when high grain concentrates (>90%) were offered at near ad libitum intake
levels (Johnson and Johnson, 1995)
 Amount of ruminal methane produced from corn was lower than that of barley
grain in ruminants due to higher starch content and slow starch degradability of
corn vs. barley grain (Yurtseven and Ozturk, 2009)
 Adding flax seed to the diet of dairy cattle can be an effective means of
reducing CH4 emissions. However, over supplement of flax seed may reduce
CH4 but at the expense of diet digestibility in addition to possible negative
effects on milk production of high-producing dairy cows
(Sejian et al., 2011)
Cont…

19. • Grinding or pelleting of forages to improve the utilization by ruminants
has been shown to decrease CH4 losses per unit of feed intake by 20-
40% when fed at high intakes (Johnson et al., 1996)
• It is recognized that CH4 production in ruminants generally increases
with forage maturity and that CH4 yield from the ruminal fermentation
of legume and legume-grass forages is also generally lower than the yield
from grass forages (Moss et al., 2000)
• Total mixed ration (TMR) feeding leads to decreased methane
production vs. separate forage-concentrate feeding (Sejian et al. 2011)
• Extracts from plants such as rhubarb and garlic could decrease
CH4 emission (McAllister and Newbold, 2008)
Cont…

20.  Ryegrass varieties containing high soluble sugar contents (i.e. 20.5 g/kg DM)
have been shown to decrease methane production per kg of live weight gain
by up to 25% in growing lambs
(Kim et al., 2011)
 Animals fed grasses with a C4 photosynthesis pathway, typical of hot
climates, produce 10 to 17% more methane than animals fed C3 grasses with
comparable digestibility and NDF content
(Archimède et al., 2011)
 Garlic and its essential oils inhibit methanogenesis significantly accompanied
with a lower acetate to propionate ratio indicating a diversion of
fermentation in a favourable direction
(Kamra et al., 2012)
Cont…

21. Supplementation of Garlic oil(Allium sativum),significantly
reduced the methane production in vitro.
(Sirohi et al., 2012)
Total CH4 production (Mcal/day) was depressed by 33% by the
utilization of alfalfa silage instead of alfalfa hay
(Benchaar et al., 2001)
It has been identified that some steers are ‘high’ and ‘some are
low’ emitters of methane on identical feed and feed intakes
(Goopy and Hegarty , 2004)
Cont…

22. Tannins
 Condensed tannins (CT) have been shown to reduce CH4 production
by 13%–16% (DMI basis) mainly through a direct toxic effect on
methanogens However, high CT concentrations can reduce the
voluntary feed intake and digestibility .
(Grainger et al., 2009)
 Legumes containing condensed tannin (e.g., Lotuses) are able to
lower methane (g kg-1 DM intake) by 12-15% .
(Beauchemin et al., 2008; Rowlinson et al., 2008)
 Two modes of action of tannins on methanogenesis have been
proposed a direct effect on ruminal methanogens and an indirect
effect on hydrogen production due to lower feed degradation
(Tavendale et al., 2005)

23. Fat
 For every 1% (DMI basis) increase in fat in the diet, CH4 (g/kg DMI) was
reduced by 3.8% (Martin et al., 2010)
 There are five possible mechanisms by which lipid supplementation
reduces methane:
1. By reducing fibre digestion (mainly long-chain fatty acids);
2. By lowering DMI (if total dietary fat exceeds 6%–7%);
3. The suppression of methanogens (mainly medium-chain fatty acids);
4. The suppression of rumen protozoa; and
5. Through biohydrogenation
(Beauchemin et al., 2008)
 The long term efficacy of lipid supplementation in reducing enteric
methane emissions was demonstrated in dairy cows receiving extruded
linseed for more than a year (Martin et al., 2011)

24.  No difference was observed in CH4 production when protected fats were
supplemented in vitro compared to control diets
( Dohme et al., 2000)
 It has been shown that the medium chain fatty acids (C8–C16) cause the
greatest reduction in CH4 production
(Dohme et al., 2000)
 Utilization of polyunsaturated fatty acids, especially from linseed,
decreases rumen methanogenesis , which may be a practical abatement
technology in ruminant production
(Jouany et al., 2008)
 The depression in CH4 production with addition of unsaturated fats has
been attributed to the fact that these fatty acids can serve as electron
acceptors during biohydrogenation in the rumen
(Hegarty, 1999)
Cont…

25. Defaunation
 The reduced ruminal methanogensis observed with
defaunation can be atributed with:
 Shift of digestion from rumen to hind gut
(Van Nevel and Demeyer, 1996)
 Loss of methanogens associated with protoza during defaunation
(Hegarty, 1999)
 The chemical reduction of protozoal numbers has been shown
to reduce methane by up to 26% (DMI basis), because
methanogens are often attached to the surface of or are
endosymbionts within rumen ciliate protozoa
(McAllister and Newbold, 2008)

26. Plant secondary metabolites
 The plant secondary metabolites usually help in reduction of
methanogens by the following mechanisms:
 Inhibition or selective removal of ciliate protozoa
(Bhatta et al., 2009)
 Improvement in fibre digestion.
(Waghorn et al., 2002)
 Better propionate production.
Calsamiglia et al., 2007)
 Direct inhibition of methanogensis.
(Bhatta et al., 2009)

27.  The active compounds extracted in methanol of Myristica fragrans emerged
out to be a useful natural plant source for the inhibition of methanogenesis
(Sirohi et al., 2012)
 Saponins extracted from different herbal plant seeds((Achyranthus aspara,
Tribulus terrestris and Albizia lebbeck) showed the significantly reduced
protozoa count, Increase in propionate(%) and decrease in acetate (%)
invitro
(Goel et al., 2012)
 A promising active compound from cashew nuts reduced methane
emissions in dairy cows by 20%
(Shinkai et al., 2010)
Cont…

28. Chemicals and additives
 Methane production was reduced by 23% when sorghum silage treated
with fumaric acid was fed to Holstein steers
(Bayaru et al., 2001)
 The HC5 bovicin bacteriocin from Streptococcus bovis has shown to
inhibit methane by as much as 50%
(Lee et al., 2002)
 Monensin (24–35 ppm) reduce CH4 production by up to 10% (g/kg DMI)
(Van Vugt et al., 2005)
 There was no significant effect of monensin sodium supplementation on
methane reduction in both cattle and buffaloes
(Sirohi et al., 2010)

29.  The combination of bromochloromethane (BCM) and a-cyclodextrin
reduced methane emission from cattle and sheep but its effect lost
only for 28 and 3 days in cattle and sheep respectively
(Dong et al., 1997)
 Dicarboxylic acids, like fumarate, malate, and acrylate, are precursors
to propionate production in the rumen and can act as an alternative H2
sink, restricting methanogenesis
(McAllister and Newbold, 2008)
 Substantial decrease in methane production were observed in lactating
goats fed with with bromochloromethane (BCM), a halogenated
aliphatic hydrocarbon
(Albecia et al., 2012)
Cont…

30. Enzymes
 Enzymes, in the form of cellulases and hemicellulases added
to the diets of ruminants, improved ruminal fibre digestion
and productivity.
(Beauchemin et al., 2003)
 cellulases and hemicellulases reduced CH4 by 28% in vivo
and 9% in vivo, respectively, perhaps by reducing the
acetate-to-propionate ratio
(Beauchemin et al., 2008)

31. Miscellanous
 A study in Australia suggested that vaccination against methanogens can reduce
methanogenesis, with a 7.7% (DMI basis) reduction in CH4, although the results
were not repeatable with subsequent vaccine preparations
( Wright et al., 2004)
 Vaccination of sheep with methanogen fractions induced antibodies that block
methane production in vitro
(Wedlock et al., 2011)
 Reductive acetogenesis, in which H2 and CO2 form acetate rather than CH4 as a
source of energy, has been suggested as an alternative to methanogenesis
(Joblin, 1999)
 Methanogens effectively out-compete acetogens for H2 in the rumen, because
the reduction of CO2 to acetate is thermodynamically less favourable than the
reduction of CO2 to CH4 (McAllister and Newbold, 2008)
 An acceptable repeatability and hereditability for methane production in
a flock of 105 sheep was observed
(Pinares et al.,2011)

32. Reverse Methanogenesis
Scheller et al., 2010

33. Conclusions
 Most of the studies on reductions in methane from
ruminants due to diet management are short-term and
focused only on changes in enteric emissions
 There is need to carry out studies with simultaneous
application of multiple dietary measures
 Mitigation options need to be evaluated not just in terms of
their effect on methane emissions but also on other rumen
functional parameters and on their final consequences on
animal production
 The mitigation strategies like vaccination and reverse
methanogensis can be potential mitigation strategies

34. Thank you