Agriculture Reference
In-Depth Information
to milk is provided, or a specific allocation factor
can be determined using the meat and milk yield
generated by the specific farming system.
An example of the effects of allocation
method on the GHG emissions per kilogram of
milk and meat is shown in Table 14.1 for a dairy
production system in Canada in which the meat
was from cull cows and grain-fed veal calves
(males and females not used as replacements) fin-
ished at 6.5 months of age at 270 kg (McGeough
et al
., 2012).
ecosystem services including the conservation
of biodiversity, water quality, wildlife habitat
and aesthetic value (Janzen, 2011). The chal-
lenge when incorporating several impact cate-
gories in a LCA is deciding on the appropriate
weighting of the various impact categories in
order to determine the ecological advantage of a
production system (Haas
et al
., 2001).
Greenhouse Gases
Greenhouse gas life cycle
assessment methodology
Environmental Impacts
Livestock production is closely linked to the envi-
ronment and LCA can be a useful way of assess-
ing the impact of this relationship. A number of
environmental impacts are of interest for live-
stock systems, including global warming poten-
tial (assessed as GHG emissions), acidification
potential (AP), eutrophication potential (EP),
abiotic depletion, desiccation, odour, water
resources, land competition and others as shown
in Table 14.2. To date, most livestock LCAs have
focused on GHG emissions, but there is increas-
ing interest to broaden the analysis for ruminant
production systems. Ruminants are a significant
source of GHG due to enteric CH
4
from ruminal
fermentation of cellulolosic feedstuffs, yet graz-
ing ruminants can also have many ancillary
environmental benefits such as helping to pre-
serve forage lands that sequester soil C reserves,
thereby withholding CO
2
from the air (Garnett,
2009). These grazing lands have many other
Animal agriculture generates about 8-10%
of global anthropogenic emissions, or higher
(16-18%) if emissions from land use change
are considered (Steinfeld
et al
., 2006; O'Mara,
2011). Given the effects of increasing GHG lev-
els on climate change and the growing demand
for food to meet population increases, mitiga-
tion of these emissions has been a focal point in
agricultural research (Garnett, 2009). Many
governments are grappling with ways of reduc-
ing GHG emissions from agriculture and signifi-
cant research is now being directed towards
developing animal husbandry practices that
lower enteric CH
4
emissions from ruminants
(McAllister and Newbold, 2008; Beauchemin
et al
., 2009; Eckard
et al
., 2010).
LCA can be a useful way of determining the
net impact of a particular mitigation strategy on
the total GHG emissions per unit of product
produced, because it accounts for all changes
Table 14.1.
Greenh
ouse gas emissions as affected by allocation method (from McGeough
et al
., 2012).
Emissions per functional unit (kg CO
2
e)
Emission allocation
to milk (%)
Milk
(kg FPCM
b
)
Meat
(kg live weight)
Meat
(kg carcass weight
c
)
Allocation method
a
No allocation
100
0.91
0
0
Economic
91
0.83
1.72
2.87
Dairy versus beef
97
0.88
1.16
1.94
IDF default
86
0.78
2.84
4.73
IDF specific
73
0.67
5.24
8.73
a
No allocation, 100% to milk; Economic, based on 5-year average of milk and meat prices; Dairy versus beef, emissions
allocated; IDF default, International Dairy Federation equation using default meat to milk ratio; IDF specific, International
Dairy Federation equation using the actual meat to milk ratio for the study.
b
Fat and protein corrected milk.
c
Calculated as
0.60 of live weight. Included meat from culled cows, all male and female calves not used as replacements, all finished as
grain-fed veal at 6.5 months of age at 270 kg.
