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Effects of dietary feedingstrategies on greenhousegas production by ruminants
University of Reading 2008 www.reading.ac.uk04 July 2013
Chris Reynolds, L. A. Crompton,
J. A. N. Mills, and D. I. Givens
School of Agriculture, Policy, and
Development
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Ruminant Nutritionand the Environment
1. Methane green house gas (GHG)
2. Nitro en nitrates N O GHG NH
- eutrophication, air quality
3. Phosphorus eutrophication
4. Manure all of the above +
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From The Times
July 10, 2007
How to stop cows burping is the new field work onclimate change
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From The Times
July 10, 2007
How to stop cows burping is the new field work onclimate change
From The TimesOctober 27, 2009
Climate chief Lord Stern: give up meat to
save the planet
Methane is 23 times more powerful than carbon dioxide as a global warming gas
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Methane Energy Loss- $$$ and GHG
Per molecule methane ~25 x
global warming effect of CO2
5
Waste of feed energy 2 to 12 %
Concern for the carbon footprintof milk, beef and lamb
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Ruminant Farm Animals asMethane Producers
Agriculture contributes43% to the UKsemissions of CH4 ~ 3 % of total GHG
wo sources
85% fermentation
15% manure
Proportion is increasing
Dairy farming accountsfor 30%
Major target for mitigation
Beef and sheep 65%
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Ruminants and GreenhouseGasses a Hot Topic!!!
7
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Methane Energy Loss
8
Bratzler and Forbes, 1940.
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Nitrogen and Methane
Excretion Studies at Reading
Respiration calorimeters and
digestion trials
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Methane Energy Loss
/d)
25
30
35
10
Dry matter intake (kg/d)
0 10 20 30
Methane(
M
0
5
10
15
20
Mills et al., 2009.
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Where Does Methane Come From?
Rumen fermentation
yields H2
Methanogenesis is a
sink for H2
C02 reduced to
Acetate
Butyrate
Propionate
Valerate
CH4 Fermentation also
occurs in hind gut
and in manure
H2
with amino acids
H2Source
Lipid
Hydrogenationunsaturated fatty acids
Microbial growthwith ammonia
MethaneCO2 + 4H2 CH4 +2H2O
Zero pool schemeH2Sink
EXCESS
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Herd Level Actions to
Reduce Methane
Reduce the overhead of non-producing or low
producing animals will deliver less methane per
litre of milk
Increased health and fertility leading to reducedculling rates
Extended lactations
Reduced age at first calving
Genetic selection for residual feed intake
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Methane Energy Loss
nergy
0.6
0.8
13
Milk yield (kg/d)
0 20 40 60
Methane/milk
0.0
0.2
0.4
Mills et al., 2009.
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Dietary Carbohydrates Methane production is related to intake
On average 30 litre/kg DMI
6.5% gross energy intake (dairy cows)
hence methane
Replacing a proportion of the fibre with starchy
feedstuffs will reduce methane per kg DMI Forage quality (digestibility) important
Consider Starch:ADF ratio as an indicator
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Effect of Forage Type on Methane
Production by Lactating Dairy Cows
30
40
DEFRA Project AC0209
0
10
20
CH4, L/kg DMI
Maize Grass
87%
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Dietary Fat and Methane
16
Grainger and Beauchemin, 2010.
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Supplemental Fat and Methane Supplemental fats reduce methane per unit
feed DMI Supply energy that does not contribute tomethanogenesis
chain fatty acids (MCFA) are particularlyeffective microbial effects?
Unsaturated fats a sink for hydrogen
May limit fibre digestion MCFA may have less adverse effects on diet
digestibility, whilst still reducing methane
negative effects on DMI?
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Effect Of Milled Rapeseed On MethaneProduction By Lactating Dairy Cows
) 500
600
700
18Con x2 RS x2 RS x1 RS4/5 x1
Methane(l
/
0
100
200
300
400
DEFRA Project LS3656
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Effect Of Milled Rapeseed On Methane
Production By Lactating Dairy Cows
MI)
25
30
35
P
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Effect Of Milled Rapeseed On MethaneProduction By Lactating Dairy Cows
ilk) 20
25
Con x2 RS x2 RS x1 RS4/5 x1
Methane(l/kg
0
5
10
15
DEFRA Project LS3656 20
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Effect Of Milled Rapeseed On Milk Fatty
Acid Composition Of Lactating Dairy Cows
00gfa)
60
80
Total saturates
Total cis MUFAs
Con x2 RS x2 RS x1 RS4/5 x1
Milkfat
tyacids(g
/
0
20
40
DEFRA Project LS3656 21
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Predicting Methane UsingMilk Fatty Acid Concentrations
22Dijkstra et al., 2010.
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Dietary Additives Organic dicarboxylic acids
Aspartate, malate and fumarate Potential propionate precursors
Compete for available H2 pool
Large dose required for relatively small effect? Low rumen pH
Unpalatable
Effects in sheep not repeated in dairy cows Nitrites, sulfites, chloral hydrocarbons, etc.
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Feed Additives Plant extracts
Tannins
Anti-methanogen effect
Inhibition of fibre degradation
Anti-nutritional factor
Defaunation action
Extensive screening programs for bioactive plant
components that improve rumen fermentation
Ionophores and other antimicrobials
Adaptation?
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Effect of Supplements on MethaneProduction by Lactating Dairy Cows
25
30
DMI
DEFRA Project AC0209
0
5
10
15
20
Control Glycerol Allicin Naked oats
Methane,
L/kg
P < 0.10
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P < 0.0120
25
lk
Effect of Supplements on MethaneProduction by Lactating Dairy Cows
0
5
10
15
Control Glycerol Allicin Naked oats
M
ethane,
L/Lmi
DEFRA Project AC0209 27
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Nitrogen Inputs and Outputsin Dairy CowsURINE N
37%
N INTAKE
503 g/day
28
MILK N
28%
FAECAL N
33%
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The Nitrogen CycleMilk (and meat)
Purchasedfeed ~25%
~75%
Manure
Soil
Crops
FertiliserN fixation
NH3
Nitrate N2O,NOx
~50%
~50%J. Moorby, 2008
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Nitrous Oxide Emissions: 1990 - 2005
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Nitrogen Excretion in Dairy Cows
urine
milk
faeces
Kebreab et al., 2000.
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Milk N/Intake N versus N Intake
Mills et al., 2009
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Efficiency of Dietary N Utilization
for Milk Protein Production
Milk N as a Percentage of N Intake
30
40%
129% 114% 100%
DEFRA Project AC0209 N intakes lower for grass-based ration
0
10
20
14% CP 16% CP 18% CP
Maize Grass
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16.0
18.0
20.0
22.0
CH4/kg
DM
12.0
14.0
16.0
18.0
4/kgFPCM
Varying NDF quality in grass diets
18 kg DM/d (90% grass & 10% concentrates)
GH GS-EC GS-LC
10.0
12.0
14.0g
GH GS-EC GS-LC
6.0
8.0
10.0gC
GH = grass herbage; GS = grass silage
= high N-fertilization = low N-fertilization
NDF quality & methaneA. Bannink
EC = early cut; LC = late cut
Bannink et al., 2010
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Reducing Greenhouse Gasses Methane numerous dietary approaches
show promise
Dietary carbohydrate and fat have effects Starch:ADF ratio as an indicator
Numerous supplements/additives
Reductions observed in sheep typically notrealized in lactating dairy cows
Nitrates, nitrous oxide and ammonia
Feed less protein how low can we go? Reduced yield may increase methane inventory
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Future Perspectives How can we improve efficiency in ruminant
milk and meat production systems and limitenvironmental impacts?
36
mprovemen s n gene cs, nu r on, an ec no ogy
e.g. feed additives, selection indices, etc.
Adoption of best practice in feeding and management
System approaches and assessments The roles of extensive and intensive systems
Must consider wider impacts of specific mitigation options
Exploiting the virtues of ruminants and grasslands