Agriculture Reference
In-Depth Information
in that the results are presented on the basis of
maintaining dietary protein supply from animal
versus plant sources, although the authors dem-
onstrate a limited understanding of livestock
production systems, which in some cases lead to
underlying assumptions for their model that are
entirely unfeasible. For example, the method-
ology indicates that the reproductive productiv-
ity of the US sheep system (farm flocks average
1.5-2.5 lambs per ewe per year whereas range
flocks average 1.0-1.5 lambs per ewe) is not
accounted for compared with the US average for
beef of 0.87% of cows producing a live calf
(USDA, 2003, 2009). Approximately twice as
many beef cows are required to produce the
same number of offspring as a set number of
ewes; therefore, even considering the fact that
lambs produce slightly less meat per carcass on
a percentage basis, this throws doubt on the
Environmental Working Group's claim that the
GHG emissions associated with lamb are app-
roximately 44% greater than those of beef.
Nutritionally, however, it is a fallacy to suggest
that protein quality does not differ between vari-
ous animal and plant sources, especially when
specific amino acids are required for human
growth and development (Bauman and Capper,
2011). Just as a recent study by Drewnowski
(2010) evaluated the economic cost per unit of
dietary food energy, evaluation of the environ-
mental impact of dietary protein sources should
be related to protein quality in order make
dietary recommendations without negatively
affecting human health.
The need to assess resource use and GHG
emissions based upon the nutrient density of
individual food products is of increasing impor-
tance to processors and retailers as product dif-
ferentiation continues to be used as a mechanism
to gain market share. Some European retail gro-
cery chains have adopted labelling schemes dis-
playing the 'carbon footprint' per unit of food,
and such schemes may be adopted in the USA in
future. However, this is a particular concern
when comparing, for example, fluid milk to
cheese. Given that it takes between 8 and 10 kg
of milk to make 1 kg of cheese, a unit weight of
cheese would be labelled with a carbon footprint
approximately ten times that of the same unit
weight of milk. This might lead the consumer to
discriminate against products that have a larger
carbon footprint, regardless of nutritional value.
Smedman
et al
. (2010) reported that milk had
the most favourable ratio of nutrient content to
GHG emissions when compared with orange
juice, soy and oat beverages and alcoholic
drinks; none the less, the challenge is to commu-
nicate these results to consumers to whom
animal products are often regarded as either
nutritionally unfavourable or environmentally
unsustainable.
Opportunities for Future Global
Environmental Sustainability
In 2006, the FAO released the oft-quoted report
'Livestock's Long Shadow', which concluded
that livestock production is responsible for 18%
of global anthropogenic GHG emissions. Despite
its adoption by the majority of media and activ-
ist groups as scientific evidence for the principal
role of livestock in causing climate change, the
FAO report was not without its detractors and
Pitesky
et al
. (2009) produced a detailed paper
outlining the flaws within the report. The most
notable issue related to the 18% statistic, which
was derived from comparing carbon emissions
from a highly detailed and inclusive LCA of
global livestock production, to the carbon emis-
sions from the fuel combustion phase of the
global transport sector. As the FAO later admit-
ted, differences in the methodology between
predicted carbon emissions from livestock pro-
duction and transport rendered the comparison
invalid. The exact proportion of global carbon
emissions produced by livestock production has
yet to be quantified although it is suggested to be
somewhat less than the original 18% estimate.
Although the FAO report was regarded as dam-
aging by many within the livestock industry, it
fulfilled two vital roles with respect to environ-
mental sustainability - the magnitude and
shock-value of the 18% figure ensured that
climate change became a priority for industry
groups, and carbon emissions from all livestock
sectors came under scrutiny.
As previously discussed, the environmental
sustainability of livestock systems is profoundly
affected by system productivity, yet the FAO's
global average includes a wide range of regional
efficiencies. The environmental effects of
regional productivity variations are exemplified
