Agriculture Reference
In-Depth Information
The AP of beef and dairy systems is highly
influenced by NH
3
emissions, therefore mitiga-
tion of AP can mainly be achieved by reducing
the amount of N excreted, particularly urinary
N (which is more highly volatile than N in faeces),
and furthermore by using improved manure
handling systems.
increase the GHG intensity of animal prod-
ucts, especially in the case of beef.
It must also be recognized that there is a
large degree of uncertainty in estimating envi-
ronmental burden, especially for GHGs due to
the uncertainties of the emissions factors used
in the analysis. Advances in the understanding
of the biological processes of GHG production
will reduce the uncertainty associated with GHG
emission factors.
To date, the application of LCA in animal
production has focused mainly on assessing
GHG emissions, because many of the other
environmental impacts (Table 14.2) are more
difficult to quantify and require further meth-
odological development before they can be
used in LCA. Furthermore, by definition LCA
focuses on environmental burdens and not
the ecological benefits afforded by livestock
production. Benefits such as creating food for
humans from inedible biomass, conservation
of grassland ecosystems, promoting the use
of perennial forages that help preserve lands,
and recycling of nutrients are not included
in LCA of animal production. Thus, there is
a need to develop LCA methodology that
accounts for the ecosystems services that ani-
mal production promotes, particularly in the
case of grazing ruminants. The carbon inten-
sity of beef production is the highest of all
meat products, in part because beef produc-
tion systems rely heavily on the use of pasture
and grazing lands. In many parts of the world,
livestock, beef cattle and sheep in particular,
are raised on lands not suitable for other types
of food production. Conversion of native
grasslands to cultivated land would lead to
habitat destruction for wildlife and decreased
biodiversity. Thus, focusing LCA only on
C-footprint can lead to incorrect recommen-
dations. Future LCA of livestock products need
to use multiple impact categories, beyond
simply GHG emissions. However, at present
there is no clear means of integrating the
information for various impacts.
Non-renewable Energy Use
Non-renewable energy use can be another indica-
tor of sustainability of livestock production sys-
tems, as it comes from finite resources. Nguyen
et al
. (2010) reported that 41-59 MJ of non-
renewable energy was used to produce 1 kg of
live weight for beef production in the EU, with
42-43% attributed to fertilizer manufacturing.
Much higher non-renewable energy use was
reported by Ogino
et al
. (2007) for a Japanese beef
production system, because of higher production
and transportation energy use (feed from the USA)
and a longer fattening period (26-28 months).
Limitations and Future Direction
Currently, the major limitation to LCA for ani-
mal products is the inability to compare
across studies due to the lack of standardiza-
tion in methodology coupled with the com-
plexity of farming systems used worldwide.
Another limitation of the current methodo-
logy for LCA of animal products is that it does
not consider the environmental impacts
related to a change in land use. The central
issue is that in some areas, especially Brazil,
expansion of livestock production contributes
to deforestation for pastureland and soybean
production for animal feeding (Steinfeld
et al
.,
2006). Hence, compelling arguments have
been made that land use change (direct
effects or through feed importation) needs to
be included in LCA of animal products,
as this omission underestimates the impact
of livestock production on climate change
(Cederberg
et al
., 2011; Weiss and Leip,
2012). While the methodology for including
land use change in LCA of animal products is
not well developed at this stage, it is likely to
happen in the future, which will undoubtedly
Conclusions
The environmental cost of producing meat
and milk must be weighed against the benefits
