Agriculture Reference
In-Depth Information
human-edible energy or protein output from live-
stock production systems. Within these metrics,
grass-finished beef had a favourable human-
edible feed efficiency ratio whether expressed in
terms of energy (1.9 MJ/MJ human-edible energy
in animal product) or protein (0.92 kg kg −1
human-edible protein in animal product) when
compared with pork (2.6 kg kg −1 human-edible
protein) or poultry (2.1 kg kg −1 human-edible
protein). It is therefore clear that feed efficiency
per se , is not an adequate measure by which to
compare differing animal proteins from a
resource use basis.
capita at 49.4 kg (CME Group, 2011); yet GHG
emissions attributable to red meat and dairy pro-
duction are equal to 3.05% of the national total
(US EPA, 2010a). If every US inhabitant removed
red meat and dairy products from their diet, the
reduction in US GHG emissions would be equal
to 0.44%. Any attempt to reduce GHG may be
considered laudable, none the less, a 0.44%
reduction (assuming that this concept was
adopted by the entire population) would make
very little difference to total emissions, especially
since it is not expressed in the context of other
human activities, for which we have at best a
tenuous grasp of the potential environmental
impact. For example, a significant reduction in
meat consumption would also necessitate devel-
opment of non-animal-based replacements for
products such as manure, leather, adhesives and
pharmaceuticals that are derived from livestock
production.
Fairlie (2010) published an elegant calcula-
tion comparing the food-supply potential of land
given the dietary preferences of the UK population.
Results demonstrated that under the constraints
of food production for a conventional, omnivo-
rous population whereby agriculture is based on
a mixture of livestock and chemical fertilizer
inputs, 1.0 ha of arable land plus 1.5 ha of pas-
tureland would feed 14 people. By contrast, 1.0 ha
of arable land would supply 20 people with a
vegan diet, yet fertilizer inputs would have to
be entirely based on chemical inputs, which
would considerably increase fertilizer and fossil
fuel requirements per unit of food. If the agricul-
tural system shifted to one based on vegan per-
maculture (without regard for the limitations of
using human sewage to fertilize crops intended
for human consumption), 1 ha of land would
feed eight people. In addition to the lower poten-
tial food supply, the increased dependence on
arable land within vegan systems and lack of
opportunities to use pastureland, thus reducing
potential improvements in biodiversity and soil
structure from proper grazing management
would also be expected to impact environmental
sustainability. The debate as to which human diet
provides the 'optimal' use of resources is likely to
continue for some time, and is unlikely to ever
gain resolution given that optimal resource use
is region- and population-specific.
The authors of a recent Environmental Work-
ing Group report (2011) should be commended
The Environmental Sustainability
of Omnivorous Human Diets
The suggestion that crops used for animal feed
could be better used to supply human nutri-
tional needs naturally leads to the question as to
whether animal agriculture is a necessary com-
ponent of the human diet. A considerable num-
ber of reports have recently claimed that
consumers could considerably reduce their car-
bon footprint by forgoing animal protein on one
or more days per week (Fairlie, 2010; Millward
and Garnett, 2010; Environmental Working
Group, 2011). The related 'Meatless Mondays'
campaign appears to originate from a paper
published by Weber and Matthews (2008) in
which the authors state that 'Shifting less than
one day per week's worth of calories from red
meat and dairy products to chicken, fish, eggs,
or a vegetable-based diet achieves more GHG
reduction than buying all locally sourced food.'
The lack of a 'control' treatment against which
to compare the removal of red meat and dairy
products from the diet renders this comparison
practically meaningless, none the less, it has
been adopted by various vegetarian and vegan
groups as proof that meat consumption is envi-
ronmentally unfriendly. Citizens of most devel-
oped nations could arguably consume less red
meat and dairy products without negatively
impacting their health status, none the less, it is
somewhat disingenuous to suggest that this die-
tary change would have a major impact on
national or global GHG emissions. For example,
the US population is generally considered to have
the greatest regional red meat consumption per
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