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Gizaw Dabessa Satessa, Mette Olaf Nielsen, Jens Legarth, Rajan Dhakal and Hanne Helene Hansen 15 October 2017
Effects of Seaweeds on in vitro rumen fermentation, methane and total gas production
• Methane (CH4) is a greenhouse gas (GHG) synthesized by methanogenic archea from hydrogen (H2) and carbon dioxide (CO2) released during ruminal fermentation
Figure 1. Synthesis of methane from H2 in the rumen
• Methane released from livestock: one of the GHG; accounting for ~28% of global anthropogenic CH4
Introduction
2CO2 + 4H2 CH4 + 2H2O
Ruminal fermentation
Methanogenic Archea
Impacts of enteric methane emission
1) Global warming and climate change
• CH4 has 25 times global warming potential compared to CO2
2) Represents loss of energy: Lowers feed efficiency and animal productivity
• Results in loss of 2 to 12% gross energy intake
Reduction of CH4 is a win/win situation:
- Environment
- Farmer economy and cow energy metabolism
½
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EU Policy
• EU countries must reduce GHG emissions by 40% in 2030 in the non-quota sector (includes agriculture) compared to 1990 (5,716 mega tons CO2 equivalents)
• Reducing CH4 emission from (ruminant) livestock sector will be a positive contribution to global efforts in GHG emission reduction
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Enteric Methane emission mitigation strategies No safe and efficient methods exist as yet:
• Which reduce enteric methanogenesis
• Without significantly reducing feed degradability and hence animal performance
Recently, seaweeds (macroalgae) have attracted interest:
• Contain bioactive compounds
• Some of these are capable of reducing methane formation
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Macroalgae (Seaweeds)
• Classified based on pigmentation as:
red macroalgae
brown macroalgae and
green macroalgae
• Contains compounds not found in terrestrial plants:
eg. complex carbohydrates: alginates, laminarin,
fucoidan, mannitol, etc.
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Macroalgae…Cont’d
• Wide range of potential uses: antibiotic, anti-oxidant,
anti-inflammatory, immunostimulants, prebiotics, etc.
• Some compounds: anti-methanogenic properties
• Different species of macroalgae differ in their anti-
methanogenic efficiency
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Macroalgae…Cont’d
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Machado et al. 2014. 9(1):e85289
Asparagopsis taxiformis Dictyota bartayresii
Figure 2. CH4 production from in vitro fermentation of different seaweed species
• In vitro study on Asparagopsis taxiformis in Australia showed about 99% inhibition of methane production
- bromoform, dibromochloromethane, chloroform, etc
Macroalgae…Cont’d
• Asparagopsis is not likely to be used to mitigate CH4 emission:
- halogenated hydrocarbons: - deplete ozone (environement) and carcinogenic (consumer health issues)
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Objectives
• Do seaweeds, which can be produced in the Northern Hemisphere, contain compounds with anti-methanogenic properties in the rumen?
• Do they interfere with feed efficiency in ruminants?
• Do they reduce enteric methane emission?
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Experimental approach
• We do not want to test this in the first instance in live animals because
1) very expensive 2) we need to know if we have safe compounds
• So, we addressed this question using an in vitro system that mimicks rumen fermentation and allows rapid screening for effective products
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In vitro system: mimicking rumen fermentation
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Beet pulp (BP)
Various seaweed products (SWP): Brown Algae
(alone or prefermented with rapeseed), Ocean Feed
Basal diets (One at a time)
Additives (One at a time)
Output - Total gas
- Methane
Maize silage (MS)
Degraded feed
(Microbiota profile)
2 systems: - Ankom - BPC
Cu
mu
lati
ve
pre
ssu
re
Time
Rumen fluid
• TG produced from pure maize silage (MS), sugar beet pulp (BP), brown algae species (BA) and Ocean Feed (OF)
• Sea weed products: virtually no gas production in rumen
(Low fermentability)
Rumen fermentation of seaweed products
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0
50
100
150
200
250
0 3 6 9 12 18 24 36 48To
tal g
as
pro
du
ctio
n in
mL/
g D
M
Duration of incubation (hours)
Effect of seaweeds on in vitro rumen gas production
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Basal feeds Additives % reduction
MS BA 18.2
OF 12.9
Basal feeds Additives % reduction
BP BA 21.3
OF 18.0
0
50
100
150
200
250
0 3 6 9 12 18 24 36 48To
tal g
as
pro
du
ctio
n in
mL/
g D
M
Duration of incubation (hours
18.2%
Maize silage
0
50
100
150
200
250
0 3 6 9 12 18 24 36 48
To
tal g
as
pro
du
ced
in
ml/
g D
M
Duration of incubation (hours)
21.3%
Beet pulp
Pure
Pure
Effect of seaweeds on in vitro rumen methane release
Basal feed Additves % reduction
MS BA 32
OF 12.5
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0
10
20
30
40
50
60
70
0 3 6 9 12 18 24 36 48
Meth
an
e r
ele
ase
d (
ml/
g D
M)
Duration of incubation (hours)
32%
a b c d
e f
a b c d
e f
0
20
40
60
80
100
MBA MOF MRBA BBA BOF BRBA
Perc
en
tag
e D
M d
eg
rad
ed
SWP mixed with MS or BP
Observed
Predicted
a
b b
c c
0
20
40
60
80
100
BA OF RBA MS BPPerc
en
tag
e D
M d
eg
rad
ed
Pure MS, BP and SWP
% digestibility of pure (0.5g):
• BA=21.9
• OF=51.5
• RBA=50.7
• MS =78.5
• BP =85.5
% degradability of feed mix: (0.5g MS + 0.1g SWP)
- Observed
- Theoretical
Effect of seaweeds on in vitro rumen feed degradation
Take home messages:
• The two seaweed products: • very low fermentability in the rumen
• very little gas produced during fermentation
• Brown Algae and to less extent Ocean Feed: • reduced total gas production from feeds by up to
21% depending on seaweed product and basal feed.
• Specifically inhibited methane production by up to 32%
• AND, importantly, rumen in vitro degradability of feeds was not affected
• Next step: • Identify and test bioactive components
• Test in live animals
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Acknowledgement
I would like to thank MAB4 and FEX for funding my PhD and University of Copenhagen for hosting my study.
I would also like to thank Mette Olaf Nielsen (Professor) and Hanne Helene Hansen (Associate Professor) for supervision
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Thank You
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