LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 3C: SHEEP AND DAIRY PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
Scenarios were investigated to consider changes in sheep management that represented the ways farmers
may respond to economic drivers, changes in genetic potential and management quality (including animal
health) and the emission factor for enteric methane. Results were compared with the current, baseline state of
sheep production and considered energy use, GHGE land occupation. All changes in scenario variables
caused effects that were linear or close to being linear within the range explored.
3. Results
With the current national flock, it takes about 22 GJ/t to produce 1 t expected edible carcass weight with the
emission of about 22 t CO2e/t, of which about 67% was from enteric methane (Table 2). “Good quality” land
included grassland from site classes 1-3 and arable land for crop production, while poor quality land included
grassland of site classes 4 to 7.
Table 2 Baseline burdens of producing 1 t expected edible carcass weight of lamb at the national level.
CED, GJ
308
GWP, t
CO2e
Eutrophication
potential, kg PO4
eqv.
Acidification
potential, kg
SO2 eqv.
Abiotic
resource
use, kg Sb
Good
quality
land, ha
Poor
quality
land, ha
22.2 22.3 100 87 13 0.5 10.0 10.5
All land,
ha
Halving the proportion of the flock that is lowland could result from economic drivers. It increases land occupation
(mainly on poorer land) and causes a relatively small increase in GHGE (from more slow growing
sheep) and decrease in CED from lower N fertilisation and concentrate use (Table 3).
Table 3 Results of changing scenarios on main burdens of producing lamb. Values are the ratio of scenario
results over baseline results.
Effect of results
Land occupation
Baseline Effect of
Good Poor
Scenario description
value scenario CED GWP quality quality Total
Proportion of ewes on lowland 37%
Halve
Double
93%
112
102%
97%
107%
88%
125%
58%
125%
60%
Proportion lowland lambs finished in
early spring
10%
Halve
Double
99%
103%
100%
101%
99%
103%
100%
100%
100%
100%
Increase sheep weight 66 kg # +5%
+10%
113%
124%
113%
126%
113%
123%
109%
119%
109%
119%
Increase in fecundity
1.2 lambs
per ewe #
-10%
+10%
111%
96%
108%
95%
111%
96%
107%
95%
107%
95%
Increase in killing out percentage 47%
+2.35%
+4.7%
99%
95%
97%
93%
99%
95%
96%
92%
96%
92%
Increase in ewe longevity, years 3.7 # +0.5 year
+1 year
100%
98%
98%
96%
100%
98%
98%
96%
98%
96%
Combined improvements Low 86% 88% 86% 89% 89%
Combined improvements High 76% 78% 77% 80% 80%
Note: # Weighted average across sheep types
Doubling the proportion of early spring lamb production increase GHGE and CED through demanding more
concentrates, but has no effect on land occupation. Increasing sheep weight (ewes and lambs) increases all
burdens, mainly because of the extra maintenance overheads of larger breeding sheep. Increasing the fecundity
of ewes by 10% reduces all burdens by 5-6%, while decreasing fecundity by 5% (e.g. through ill health,
such as Schmallenberg virus) increases burdens by 6-8%. Increasing the killing out percentage from 47% to
51.7% (i.e. relative increase of 10%) reduces all burdens by 8%. Increasing ewe longevity by 0.5 years
(about 13% increase) reduces burdens by about 5%.
The scenario variables that are under most managerial and technical influence were combined at low and
high levels to assess the potential for improvement (this excluded a change in the proportions of the national
flock). The low level improvements combined to reduce burdens by about 14% and the high level improvements
by about 24% (Table 3).