What Can Improved Feeding Do To Increase Efficiency and Reduce Emissions?

© University of Reading 2008 www.reading.ac.ukwww.reading.ac.ukwww.reading.ac.ukwww.reading.ac.uk15 December 2009

Chris Reynolds, L. A. Crompton,

and J. A. N. Mills

School of Agriculture, Policy, and Development

“The Perfect Storm”- Prof. John Beddington 2008

• As the world's population grows, competition for food,

water and energy will increase. Food prices will rise, more

people will go hungry, and migrants will flee the worst-

2

people will go hungry, and migrants will flee the worst-

affected regions. It is predicted that by 2030:

– The world's population will rise from 6bn to 8bn (33%)

– Demand for food will increase by 50%

– Demand for water will increase by 30%

– Demand for energy will increase by 50%

“The Perfect Storm”- Demand for food will increase by 50%

3www.bbc.co.uk, 2009.

“The Perfect Storm”- Climate change will add to the challenge

4

livestock’s long shadow

environmental issuesand options

FAO, 2006

Ruminant Nutrition

and the Environment

1. Methane – green house gas (GHG)

2. Nitrogen – nitrates, N2O, NH32. Nitrogen – nitrates, N2O, NH3

Eutrophication, GHG, air quality

3. Phosphorus – eutrophication

4. Manure – all of the above +

No Process is 100% Efficient!!

Bill Weiss, The Ohio State University

Improving the Efficiency of Energy Utilization

• Efficiency of feed conversion

–Animal factors

8

–Animal factors

• Efficiency of the production system

–Economic and wider issues

– Life cycle analysis, etc.

Feed Conversion Efficiency

9Linn et al.

Energy Partition in Ruminants

10

- 86% of the variation in net energy supply across diets

attributable to variation in digestible energy

Residual Feed Intake

11

Berry, 2008.

Residual Feed Intake

12

Hegarty et al., 2007.

Energy Partition in Ruminants

13

From The TimesJuly 10, 2007

How to stop cows burping is the new field work on climate change

Methane Energy Loss- $$$ and GHG

• Per molecule methane ~25 x

global warming effect of CO2

15

• Waste of feed energy – 2 to 12 %

• Concern for the ‘carbon footprint’

of milk, beef and lamb

Where is it from?

• Rumen fermentation

yields H2

• Generally N source

impacts yield of H2

• Methanogenesis is a

sink for H2

Acetate

H

Butyrate

Microbial growth

Propionate

Valerate

sink for H2

– C02 reduced to CH4

• Fermentation also

occurs in hind gut and

in manure

H2

Microbial growthwith amino acids

H2 Source

Lipid Hydrogenation

unsaturated fatty acids

Microbial growthwith ammonia

MethaneCO2 + 4H2 →→→→ CH4 +2H2O

Zero pool schemeH2 Sink

EXCESS

Ruminant farm animals as

methane producers

• Agriculture contributes

43% to the UK’s

emissions of CH4

• IPCC two sources

– 85% fermentation

– 15% manure– 15% manure

• Proportion is increasing

• Dairy farming accounts

for 30%

• Major target for

mitigation

• Beef and sheep 65%

Nitrogen and CH4 Excretion Studies at Reading

Respiration calorimeters

vs

boxes, head chambers

Methane Emission Measurements

SF6 Technique Polytunnels

Methane Energy LossM

eth

ane/G

ross

en

erg

y in

take (

%)

7

8

9

20Dry matter intake (kg/d)

0 10 20 30

Me

tha

ne/G

ross

en

erg

y in

take (

%)

2

3

4

5

6

Mills et al., 2009.

Methane Energy LossM

eth

an

e (

MJ/d

)

20

25

30

35

21Dry matter intake (kg/d)

0 10 20 30

Me

tha

ne

(M

J/d

)

0

5

10

15

20

Mills et al., 2009.

Methane Energy LossM

eth

an

e/m

ilk e

ne

rgy

0.6

0.8

22Milk yield (kg/d)

0 20 40 60

Me

tha

ne

/milk

en

erg

y

0.0

0.2

0.4

Mills et al., 2009.

What can we do about CH4?

• Changes at the herd level– Increasing longevity (reduced culling)– Extended calving intervals for high producing cows– Increasing system intensity (more milk per cow)– Genetics

• Changes to nutrition (~30 L CH /kg DMI)• Changes to nutrition (~30 L CH4/kg DMI)– Increase starchy feedstuffs & reduce fibrous feeds– Increase dietary fat– Additives

• Yeasts• Plant extracts• Organic acids

• Other methods– Vaccination

Herd level actions

• Reduce the overhead of non-producing or low producing animals will

deliver less methane per litre of milk

• Increased health and fertility leading to reduced culling rates

• Extended lactations

• Reduced age at first calving

• Genetic selection for low residual feed intake

Nutrition - carbohydrate source

• Methane production is related to intake

– 30 litre/kg DMI

– 8% gross energy intake

• Fibre digestion leads to excess hydrogen and hence

methanemethane

• Replacing a proportion of the fibre with starchy feedstuffs

will reduce methane per kg DMI

• Consider Starch:ADF ratio as an indicator

Nutrition - supplementary fat

• Polyunsaturated fats and saturated medium chain fatty acids (MCFA) are effective

• Unsaturated fats ‘mop up’ hydrogen, but limit fibre digestiondigestion

• MCFA may have less adverse effects on diet digestibility, whilst still reducing methane significantly

• MCFA present in some oilseeds and coconut oil– Potential for large reduction with high inclusion

Nutrition - additives

• Organic dicarboxylic acids

– Aspartate, malate and fumarate

– Potential propionate precursors

– Compete for available H2 pool

• reduction of fumarate to succinate

– Mechanism: removing H2 stimulates fibre digestion?

– Large dose required for relatively small effect

• 10% reduction in CH4 requires over 2 kg fumarate

• Low rumen pH

• unpalatable

Nutrition - additives

• Plant extracts

– Tannins

• Anti-methanogen effect

• Inhibition of fibre degradation

– Saponins

• Anti-nutritional factor

• Defaunation action

• Screening programs underway

– EU programmes

Methane Energy Loss

29

Martin et al., 2009.

Vaccination

• Immunise against rumen methanogens

• Early stages of application in practice

• Variable results

– Approx 8% reduction in methane

• Further refinements may increase efficacy

– Greater range of antibodies required

Future Perspectives

• How can we improve efficiency in ruminant

milk and meat production systems and limit

environmental impacts?

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– Improvements in genetics, nutrition, and technology…

• 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

Thank you

© University of Reading 2008 www.reading.ac.ukwww.reading.ac.ukwww.reading.ac.ukwww.reading.ac.uk15 December

2009

Thank you