This document discusses research on the impact of genetic selection for performance traits on methane emissions from Merino sheep. It finds that selecting for increased meat or wool production (14% MP index) could potentially increase or decrease methane emissions depending on the genetic correlations between methane production and the selected traits. If correlations are positive, methane would increase with selection, but if negative, methane would decrease. The economic implications are that selecting for methane reduction may be worthwhile if negative correlations exist and carbon prices are high enough to offset reduced production. Sensitivity analyses show results are impacted by assumptions about genetic parameters. In conclusion, whether measuring methane or feed intake is economically justified depends on known methane-production correlations.

1. Impact of genetic selection for
performance on methane
f th
emissions from Merinos
David Cottle
March 2009
Wellington,
Wellington NZ
1

2. Background
2

3. Background
3

4. Background
4

5. Background
5

6. Background
6

7. Background
Feed intake-
methane
7

8. Background
8

9. Background
Total gross turnover category < $100,000 $100,000- $200,000- $400,000 +
(Total cash receipts + buildup in trading stocks) $200,000 $400,000
Sheep numbers at June 30th 4,714 8,764
1,305 2,776
Maiden ewes 507 952
139 271
Breeding ewes 2,027 3,809
558 1,086
Wethers 1,016 1,951
336 711
Lambs 1,094 2,120
257 674
Rams 70 101
15 34
Total DSE’s 4,839 8,996
1,340 2,850
Total wool production (Kg greasy) 5,605 11,786 23,410 42,017
Farm land area (Ha) 1,989 3,000 9,445 16,700
Cropping area (Ha) 21 52 93 425
Nitrogen fertiliser (Kg N) 966 2,392 4,278 19,550
Greenhouse emissions (TCO2-e)
CH4 – enteric
178 371 635 1,198
N2O - N Fertiliser
1 3 6 29
N2O – indirect
15 31 54 111
N2O - dung, urine
19 40 69 131
Total farm emissions
214 446 764 1,469
Models of 4 average sheep specialist farms using the Uni. Melbourne emission calculators,
considering only direct emissions liable under Australian calculation methodologies
g y g
( www.climatechange.gov.au/inventory/methodology/index.html).
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Emissions that farms would be liable for if they become CPRS-covered, or are allocated a tax/fee
that is equivalent to the cost of buying emission permits (likely) (Keogh and Cottle, in press)

10. Methods
• The 10 trait selection index (desired gains) program
MTIndex was used to construct an index based on
SGA Merino 14%MP without yFDCV and SS but
14%MP, SS,
with methane (kg/year.ewe) and feed intake
(kgDM/year.ewe) in the breeding objective
• Methane was given an EV based on Kg Methane X
21 /1000 X (permit price ($/CO2-e)).
– The UNFCCC attributes Methane a 100 year GWP of 21
– Permit price was varied from zero to $500/tCO2-e
• Feed intake was given an EV of zero,-$0.02 or -
$0.10/kg (Ponzoni 1988)
• These two traits were either used as selection
criterion (i e assumed measurement possible) or not
(i.e.
10

11. Methods
11

12. Methods
14% MP Index
-ve
12

13. Methods
2.05 => SD index 10
NLW EV – lamb’s CH4
lamb’s CH4 = 0.6 * 7.3kg * Methane REV
-0.16 kg/ewe CH4/gen/i =
10% reduction in 10 years
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14. Methods
$20-$70/tonne
Australian Treasury economic modelling:
CPRS-5 (a 5% emission reduction by 2020)
CPRS 15
CPRS-15 (a 15% reduction by 2020)
2020).
Price $/tCO2-e is somewhat misleadingly called the carbon
price
EV kg methane = $/tCO2-e * 21 (GWP) /1000
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15. Methods
20.5 µm flock
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16. Results
Positive methane – production correlations
Implicit price to achieve
desired i
d i d gain
Zero $/tCO2‐e is current situation
CH4 would increase with 14% MP if
would increase with 14% MP if
<$180/tCO2‐e
Wool ~ $36/ewe/year
Methane ~ -$4/ewe/year
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17. Results
Positive r
Implicit price to achieve
desired i
d i d gain
Not worth selecting for
methane
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18. Results
Positive r
Feed EV increased – similar results
Both (sire) – sire, half sib records available (stud)
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19. Results
Negative correlations
Implicit price to achieve
desired gain
Zero $/tCO2‐e is current situation
CH4 would decrease with 14% MP
would decrease with 14% MP
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20. Results
Negative r
Implicit price to achieve
desired gain
Zero $/tCO2‐e is current situation
CH4 would decrease with 14% MP
would decrease with 14% MP
If correlations negative
than it could be worth
selecting for methane
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21. Results
Negative r
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22. Sensitivity analyses (EV, rp, rg se’s)
Positive r
Negative r
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23. Sensitivity
Methane
+ve
45
40
35
30
25
20 Frequency
15
10
5
0
0.08 0.16 0.24 0.31 0.39 0.47 0.55 More
Methane response (per 10 years)
30
25
20
-ve
15
Frequency
10
5
0
-1.05 -0.84 -0.62 -0.40 -0.18 0.04 0.26 More 23

24. Conclusion
Can only assess whether it is worth
measuring feed intake or methane to
g
reduce methane when methane –
p
production correlations are known
– Positive r: very unlikely to be economic
– Negative r: maybe
24

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26. Acknowledgements
Rob Banks
Kevin Atkins
Julius van der Werf
Greg Lee
G L
Mick Keogh
Rich Eckard
Ri h E k d
Roger Hegarty
Peter Amer
Thanks 26