Agriculture Reference
In-Depth Information
250
200
150
100
50
0
1860 American
bison population
2007 US dairy
industry
Fig. 11.4.
Comparative annual carbon footprints of the 1860 American bison population and 2007 US
dairy industry, adapted from Capper (2011b). The carbon footprint for American bison is based on CH
4
and N
2
O emissions resulting from forage dry matter intakes for age-appropriate bodyweights and
population dynamics, emission factors are from US EPA (2007).
of pasture-based dairy, it is logical to suggest
that such systems may only gain a significant
environmental advantage over conventional
dairying when they support milk production
without negatively affecting milk yield. How-
ever, USDA (2007) data revealed a 26% decrease
in milk yield per cow in organic compared with
conventional systems, and peer-reviewed papers
comparing organic and conventional produc-
tion cite decreases in milk yield ranging from
14% to 40% (Zwald
et al
., 2004; Sato
et al
.,
2005; Rotz
et al
., 2007). Assuming that dairy
breed and bodyweight remain static, a reduc-
tion in milk yield means that the dairy popula-
tion size must increase in order to maintain
total fluid milk production. Projecting out to
the year 2040 when the US population is
predicted to plateau at 340 million people, sup-
plying the entire population with their USDA-
recommended 0.71 l of low-fat milk (or its
equivalent) per day through organic rather
than conventional production practices would
require 3.5 million additional animals to be
added to the national herd (Capper
et al
., 2008).
Land use would concurrently increase by 3.1 mil-
lion ha (a 30% increase) and the carbon foot-
print of organic dairy production would be 13%
greater than that of conventional production.
It may be suggested that the rise of ethical con-
sumerism (Singer and Mason, 2006) and asso-
ciated preference for specific production system
or management practices is a direct conse-
quence of the greater incomes, food availability
and consumer choice enjoyed by consumers
within developed countries compared with less
developed regions of the world. Indeed, an
African official from the FAO was quoted within
a newspaper report of a conference dedicated to
genetically modified food as stating that:
'Organic farming is practiced by 800 million
poor people in the world because they can't
afford pesticides and fertilizers - and it's not
working' (McNeil, 2000).
Environmental Sustainability of
Monogastric Production Systems
Compared with ruminant production sys-
tems, swine and poultry industries are
generally considered less environmentally
threatening with regards to resource use and
GHG emissions. Estimates of the carbon foot-
print of monogastric animal protein produc-
tion range from 2.8 to 4.5 kg CO
2
kg
−1
pork
(Strid Eriksson
et al
., 2005; Vergé
et al
., 2009;
de Vries and de Boer, 2010) and 1.9 to 2.9 kg
CO
2
kg
−1
chicken (Katajajuuri, 2008; Pelletier,
2008; Cederberg
et al
., 2009). None the less,
given the increase in poultry and swine con-
sumption predicted to occur over the next
