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Livestock, livelihoods and the environment: Finding the balance

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Livestock, livelihoods and the environment: understanding the
Mario Herrero
, Philip K Thornton
, Pierre Gerber
and Robin S Reid
Livestock are a global resource of significant benefits to society
in the form of food, income, nutrients, employment, insurance,
traction, clothing and others. In the process of providing these
benefits, livestock can use a significant amount of land,
nutrients, feed, water and other resources and generate 18% of
anthropogenic global greenhouse gases. The total demand for
livestock products might almost double by 2050, mostly in the
developing world owing to increases in population density,
urbanization and increased incomes. Multiple existing trade-
offs and competing demands for natural resources will
intensify, but reducing livestock product demand in places and
capitalizing on the positive aspects of livestock systems such
as the potential for sustainable intensification of mixed
systems, the potential of ecosystems services payments in
rangeland systems and well-regulated industrial livestock
production might help achieve the goals of balancing livestock
production, livelihoods and environmental protection.
International Livestock Research Institute (ILRI), P.O. Box 30709,
Nairobi, Kenya
Food and Agriculture Organization of the United Nations (FAO),
Via delle Terme di Caracalla, Rome, Italy
Center for Collaborative Conservation, Colorado State University,
Fort Collins, CO 80523, USA
Corresponding author: Herrero, Mario (
Current Opinion in Environmental Sustainability 2009, 1:111–120
This review comes from the inaugural issues
Edited by Rik Leemans and Anand Patwardhan
1877-3435/$ – see front matter
#2009 Published by Elsevier B.V.
DOI 10.1016/j.cosust.2009.10.003
Livestock, as part of global ecological and food production
systems, are a key commodity for human well-being.
Their importance in the provisioning of food, incomes,
employment, nutrients and risk insurance to mankind is
widely recognized [1,2].
Livestock systems, especially in developing countries, are
changing rapidly in response to a variety of drivers.
Globally, human population is expected to increase from
around 6.5 billion today to 8.2 billion by 2050 [3]. More
than 1 billion of this increase will occur in Africa. Rapid
urbanization and increases in income are expected to
continue in developing countries, and as a consequence
the global demand for livestock products will continue to
increase significantly in the coming decades.
Livestock systems have often been the subject of sub-
stantial public debate, because in the process of providing
societal benefits, some systems use large quantities of
natural resources and also emit significant amounts of
greenhouse gases.
Considering that the demand for meat and milk is increas-
ing, and that livestock is only one of many sectors that will
need to grow to satisfy human demands, more trade-offs
in the use of natural resources can be expected. This
paper examines the key global trade-offs arising between
livestock rearing, human well-being and environmental
sustainability. These trade-offs not only have global con-
sequences but also have local impacts on livelihoods and
the environment. We use this information to formulate
research questions that require significant attention to
develop options for ensuring that livestock can continue
to provide important livelihood benefits while improving
the sustainability of agroecosystems.
Livestock—a key global commodity
Livestock systems occupy 45% of the global surface area
[4] and are a significant global asset with a value of at least
$1.4 trillion. Livestock industries are also a significant
source of livelihoods globally. They are organized in long
market chains that employ at least 1.3 billion people
globally and directly support the livelihoods of 600
million poor smallholder farmers in the developing world
[1,2]. Keeping livestock is an important risk reduction
strategy for vulnerable communities, as animals can act as
insurance when required. At the same time they are
important providers of nutrients and traction for growing
crops in smallholder systems [5]. Livestock are also an
important source of nourishment. Livestock products
contribute 17% to global kilocalorie consumption and
33% to protein consumption globally, but there are large
differences between rich and poor countries [3].
Understanding and managing the demand for
livestock products
Understanding and managing the demand for livestock
products is essential for assessing the interrelationships
and trade-offs arising between livestock systems, liveli-
hoods and the environment.
Vast differences in the level of consumption of livestock
products exist between rich and poor countries (Table 1). Current Opinion in Environmental Sustainability 2009, 1:111120
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The level of consumption of milk and meatper capita in the
developed world is higher than in the developing world but
there is significant heterogeneity from country to country.
The demand for livestock products is rising rapidly in
developing countries, mainly as a consequence of
increased human population, urbanization and rapidly
increasing incomes (see [6
,7] for reviews). Until 2002
the total consumption of animal products in both the
developed and the developing world was roughly similar.
However, recent projections [3] show that meat and milk
total consumption in the developing world will be at least
double than in the developed world by 2050, owing to the
combination of the factors mentioned above. Even with
this level of growth, the consumption of meat and milk per
capita to 2050 in the developing world will still be less than
half that in the developed world. These differences in
consumption per capita partly explain why the environ-
mental footprints of livestock products in the developing
and the developed world differ by orders of magnitude [8].
The increased consumption of livestock products in the
developing world has positive impacts on mortality and
cognitive development of infants. On the contrary, the
high level of consumption of animal products is also cited
as a source of obesity, cancer, and heart problems in the
developed world [9]. These somewhat opposing para-
digms require a two-pronged approach. On the one hand
we need to find strategies to reduce the demand of
livestock products in the developed world, while on
the other we need to sustainably intensify production
to meet demand in the developing world.
Livestock production systems—different use
of resources, different trade-offs
A heterogeneous array of livestock production systems
satisfies the demand for animal products globally. Some of
these systems are more important than others in different
regions but several trends emerge and four simple
categories of systems can be recognized: pastoral/agro-
pastoral, mixed extensive systems, mixed intensive sys-
tems, and specialized/industrialized systems.
Globally, agro-pastoral and pastoral systems cover 45%
of the earth’s usable surface [4] and supply 24% of the
global meat production [6
]. Projections by Bouwman
et al. [51] show that in the next three decades 30% more
grass will be required to meet the global demand for
of fertilizers in parts of the world will be necessary to
meet these increases. The environmental impacts of
grazing systems intensification and the use of additional
fertilizer inputs need to be carefully weighted against
the potential increases in grassland productivity and
animal production.
The developing world produces 50% of the beef, 41% of
the milk, 72% of the lamb, 59% of the pork and 53% of the
poultry globally [3,6
]. These shares are likely to
increase significantly to 2050 as rates of growth of livestock
production in the developing world exceed those in devel-
oped countries (>2%/yr and <1%/yr, respectively) [3,10
Mixed extensive and intensive croplivestock systems
produce 65%, 75% and 55% of the bovine meat, milk
and lamb, respectively, of the developing world share
]. This type of system is of particular importance from
a food security and livelihoods perspective because over
two-thirds of the human population live in these systems
and apart from livestock products, they also produce close
to 50% of the global cereal share [10
]. These are also the
systems that are under the highest environmental press-
ures, particularly in high potential areas of Asia, where
water tables and biodiversity are decreasing [3,10
], and in
Africa where soil fertility is rapidly declining [5].
Industrial pork and poultry production account for 55%
and 71% of global pork and poultry production, respect-
ively [6
]. These systems will account for over 70% of the
increases in meat production to 2030, especially in Latin
America and Asia [6
,11]. However, large concentrations
of animals are creating pollution problems and promoting
transfers of nutrients and resources from ecologically
vulnerable parts of the world. The demand for maize
and coarse grains is projected to increase by 553 million
tones by 2050 as a result of this monogastric expansion,
and will account for nearly half of the grain produced in
the period 20002050 [3].
While most production in the developed world is
intensive and/or industrial, recent research [12] suggest
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Table 1
Projections of demand for livestock products in the developed and the developing world (adapted from Thornton and Herrero [7], data
from Rosegrant et al. [3])
Year Annual per capita consumption Total consumption
Meat (kg) Milk (kg) Meat (Mt) Milk (Mt)
Developing 2002 28 44 137 222
2050 44 78 326 585
Developed 2002 78 202 102 265
2050 94 216 126 295
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that a shift towards integrated mixed farming systems
in North America could still maintain high and profit-
able levels of production and at the same time have
noticeable beneficial environmental impacts such as
increased carbon sequestration, increased efficiency
in use of resources, and recycling of nutrients, for
Research on mechanisms for de-intensifying these sys-
tems is an exciting new opportunity that requires further
research to fully elucidate the impacts of these changes on
food supply and environmental impacts.
Table 2 presents some of the key trade-off aspects and
questions to consider when examining the linkages be-
tween livestock, livelihoods and the environment for each
of these systems.
Livestock and land use change
Land inextricably links livestock to natural resource man-
agement. Livestock is not only the largest land use system
on Earth, mainly in the form of pastoral systems that
occupy up to 45% of the global land area [4], but also feed
production, grazing, water and nutrient use, and biodi-
versity are largely dependent on land use and its potential
change [13].
Different types of livestock systems have different impacts
on land use and its change. Some of these impacts are direct
and others indirect [4,6
] and are explained below.
Land use change and evolving livestock systems
Livestock systems are evolving at very fast rates, especi-
ally in the developing world [10
] and several theories of
agricultural intensification and change exist to explain
Livestock, livelihoods and the environment: understanding the trade-offs Herrero et al. 113
Table 2
Main trade-offs between livestock, livelihoods and the environment
Main trade-offs questions
General Can we meet the demand for livestock products in an environmentally sustainable way or will the demand for
livestock products be forced down as trade-offs for resources increase livestock product prices?
Will reductions in demand for livestock products in the developed world lead to higher environmental
sustainability? What will be the effects on producers?
Can livestock product prices be maintained at low levels while accounting for the full environmental costs of livestock
production? What will be the impacts on the poor?
Will livestock systems intensification lead to more sustainable livestock benefits for society?
Can the limits to sustainable intensification be adequately defined and indicators for measuring it developed and
monitored in livestock systems?
Pastoral and
Increased demand for livestock products presents a real potential for increasing incomes of livestock keepers but
increases in extensive livestock production to meet demand fuel deforestation in the neotropics. Can this be reversed?
A significant carbon sequestration potential exists in pastoral systems in Africa and Latin America but systems of
payments for environmental services (measurements, monitoring, and payments) maybe too difficult to implement
effectively. What are the alternatives?
Pastoralists could participate of the economic benefits of livestock/wildlife co-existence but human population density,
agricultural intensification are increasing rangeland fragmentation. Can this be reversed?
Mixed croplivestock
Intensifying the diets of ruminants can decrease methane produced per unit of output, but can this be done
without increasing demand for grains?
Intensification of production may increase food production in parts of the developing world but it could also erode
the diversity of animal and plant genetic resources as more productive animals and plants are sought. What is
the best compromise?
Africa: Sustainable intensification of mixed extensive areas possible but significant investment required in services,
and markets. Can we target investments adequately?
How do we increase productivity and incomes in these systems without significantly reducing soil fertility? Can the
roles of livestock be re-defined?
Asia: very high levels of production have been achieved but at the expense of significant reductions in the water tables in
places. How to source feeds for ruminants in these systems will be a real challenge under more astringent irrigation levels.
Mixed systems in North America gaining significant research interest but will these systems remain as productive
and economically viable as their more industrialized counterparts?
Industrial systems Large efficiency of conversion of output/unit of feed in the productivity of monogastrics is possible but dependence
on concentrates will increases demands for feed grains that in turn fuel deforestation in the neotropics.
What are alternative options?
Demand for livestock products has significantly increased the production of chicken and pigs. This has reduced prices
of meat for poor consumers but at the same time has caused pollution problems in places. Can we create easy
regulatory framworks for environmental polution?
Systems in North America and Europe are heavily subsidized to maintain certain environmental and landscape benefits
but at the same time creating demand for feed (grains) and resources elsewhere thus fuelling deforestation. Is this
sustainable? How do we account for these indirect effects? Current Opinion in Environmental Sustainability 2009, 1:111120
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this phenomenon. Several types of transition can be
From pastoral to agro-pastoral systems This occurs, amongst
others, as a result of pastoralists having to sedentarize
owing to rangeland fragmentation and the need for social
changes that demand income diversification and entry into
the cash economy [14].In some parts of the world this
transition does not occur as land is not suitable for cropping
and pastoralism remains the sole form of livelihoods sys-
tem. How to reduce the risk and vulnerability of people and
their assets while maintaining the ecological stability of
these areas remains one of the important research areas on
livestock, livelihoods and the environment.
From agro-pastoral systems to mixed crop/livestock systems of
different degrees of intensification: This transition occurs
mainly as a result of increased human population
densities and associated increases in services and mar-
kets. In these systems, farm sizes usually decrease as
population increases and loss of soil fertility (carbon and
other nutrients) through the years in the absence of land
for fallows significantly reduce soil carbon and sub-
sequent farm productivity [15]. At the same time the
role of livestock increases in the provision of manure for
crops and cash flow from the sales of animal products. In
places with good market access, these systems could
sustainably intensify by replenishing nutrients from inor-
ganic sources and promoting better regulated manage-
ment practices and by creating market incentives to sell
animal products.
In some cases, climate change is likely to reverse this
transition, especially where losses in the length of grow-
ing period might reduce the possibility of cropping in
marginal areas. Farmers might then have to revert to
livestock rearing as the only viable livelihood system [52].
From mixed croplivestock systems to specialized/industrial
landless systems: This form of systems evolution is
explained in detail by Naylor et al. [16]. Once market
orientated smallholder production systems have intensi-
fied to significantly close yield gaps in crop and livestock
production, increases in efficiency gains and opportunity
costs for the land determine the viability of such enter-
prises. As a result farms tend to specialize, produce high
value commodities, or shift towards industrial and land-
less systems where their dependence on labor and
resources produced in surrounding areas becomes more
limited. These systems, however, are dependent on
resources elsewhere and transport of raw materials,
imports of grains, and heavy nutrient loadings owing to
large concentrations of animals [6
] become important
issues. Some studies suggest that in places, these systems
need to de-intensify and/or be regulated so as to ensure
the viability of some ecosystems services, notably water
] and minimize deleterious impacts on human health.
The combination of these systems is shaped significantly
by agro-ecology, amongst other factors, which determines
agricultural potential and makes certain systems predo-
minate over others. A similar transition happened through
Europe since the industrial revolution and is now the
subject of significant environmental management [17].
The livestock and deforestation debate
The linkage between livestock and deforestation has
been a topic of considerable research (see [18,19
The livestock and deforestation debate centers on two
main phenomena related to different livestock pro-
duction systems and their evolution. The first one is
the direct conversion of forests into pastures for extensive
cattle production, primarily in the neotropics [18].
According to several authors [18,19
,20,21] extensive
cattle enterprises have been responsible for 6580% of
the deforestation of the Amazon (rate of forest loss of 18
24 million ha/yr). Some of these systems are changing and
intensifying towards mixed crop/livestock systems and
dairy production [20,22,23] as a result of new roads and
markets and conversion of pastureland into cropland
[18,21,22]. This is expected to reduce deforestation rates
as farmers could increase efficiency and be able to obtain
more product per unit of resource used [6
], though this
view has been recently contested [20]. At the same time,
forest is directly cleared for growing crops, like soybeans,
mostly to feed pigs and poultry in industrial systems and
to provide a high protein source for concentrates of dairy
cattle (0.40.6 million ha/yr) [18,19
,21]. The rate of forest
loss for crops is projected to increase as the demand for pig
and poultry meat increases at faster rates than the con-
sumption of red meats [6
,21]. The combined forest loss
from cattle and feedstock production accounts for
approximately 2.4 billion tones of CO
emissions world-
wide [6
,24]. Figure 1 shows spatially the areas in South
America that are likely to experience forest loss as a result
of these phenomena.
Most soybeans are for export. This introduces the
additional indirect effect of environmental impacts
embedded in trade (in animal products or in resources
for livestock production, in this case feeds) [6
]. The
EU and China are the biggest importers of soybeans from
Brazil, and so their livestock industries need to be held
accountable for a part of the CO
emissions from this
deforestation. This is slowly occurring, as the EU applies
trade regulatory frameworks and certification schemes for
environmental compliance, but schemes have proven
difficult to apply locally [19
]. Indirect effects and
embedded CO
and methane emissions are aspects that
are becoming more and more relevant as countries pre-
pare to trade greenhouse gas emissions globally [24].
Several studies have also applied it to ecological foot-
prints [8], water (virtual water [25]) and some nutrients,
notably nitrogen [26], but this will eventually be
applicable to a range of other resources.
114 Inaugural issues
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Livestock and nutrient cycles
The role of livestock in nutrient cycles has received a
wealth of attention in the developed [2628] and the
developing world [29,30]. According to Sheldrick et al.
[29], nutrients in manure as a proportion of total soil
nutrient inputs account for 14% of Nitrogen, 25% Phos-
phorus and 40% of Potassium. However, there is large
spatial heterogeneity depending on the type of system,
resource endowment, crops planted, and soils, for example
[30]. Livestock become more important as a source of soil
nutrients in situations where reliance on fertilizer is low,
like in SubSaharan Africa, as they are often the only source
of carbon, nitrogen and other nutrients [26,30].
Cattle are the largest contributors to global manure pro-
duction (60%), while pigs and poultry account for 9% and
Livestock, livelihoods and the environment: understanding the trade-offs Herrero et al. 115
Figure 1
Predicted deforestation hotspots in South America 20002010 (Wassenaar et al. [21]). Current Opinion in Environmental Sustainability 2009, 1:111120
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10%, respectively. Recovery of nutrients from manure is
highly variable and depends significantly on infrastruc-
ture and handling. Europe-wide analyses [28] show that
approximately 65% of manure N is recovered from barns.
Almost 30% of the N lost is during storage and maximum
N cycling efficiencies (NCE) as N for crops was around
52%, though with large differences between member
states. A large range of variation in NCE is also found
in manure management systems in the developing world
[30]. According to the Rufino et al. [30], manure handling
and storage and synchrony of mineralization with crop
uptake are key ways of increasing NCE in smallholder
systems. This is a subject that still requires considerable
research as animal numbers will increase to satisfy human
demand for livestock products and therefore the import-
ance of manures may also change. More attention will
have to be paid as systems intensify as more manure could
be beneficial in some systems, but the potential for
increased leaching and contamination of water sources
will also increase.
Livestock and water
The linkages between livestock and water use have not
received as much attention as other aspects related to
livestock and the environment. Recent analyses show that
water use for livestock represent 31% (2180 km
/yr) of the
total water used for agriculture (7000 km
/yr) [31]. This
represents 840 km
transpired from grassland systems and
1340 km
for growing feeds. Scenarios of projections of
water use have shown that if the demand for livestock
products is to be met, water use from agriculture will need
to almost double (13 500 km
/yr), and this will be related
to the increased needs for feed production throughout the
world. Trade-offs with other sectors and competition of
water will be significant in this case, especially with water
for human consumption and industry. Water pollution,
could increase as a result of additional intensification of
production, especially in parts of developing countries, if
unregulated [6
Significant variability exists in estimates of livestock
water productivity (livestock benefits/water input [32])
from different livestock production systems and/or live-
stock products. The main source of variation is not the
direct water consumption of animals (10%) but the water
embedded in feed production (90%)[32]. This varies
significantly dependent on location, type of system, feed
resources available, diet diversity and intensification
(grains vs forages vs crop residues), and level of pro-
duction [32]. Hence, depending on the types of systems
that predominate, different regions are associated with
different proportions of the water used for feed pro-
duction or for grazing [31]. In rangeland systems, water
productivity can be significantly improved by rangeland
management [33
]. According to some studies [33
], this
source alone has the potential to reduce additional water
use in agriculture by 45% by 2050. This possibility
remains untapped and should be the source of significant
One of the biggest trade-offs in water use happens in
irrigated croplivestock systems with significant feed
deficits during parts of the year when water has to be
used for crops for direct human consumption rather than
for green fodders. Currently 15% of evapotranspiration in
these systems is associated with feed production [6
] but
if demand for livestock products increases, the trade-off
for irrigated water use between food and feed will
increase. At the same time, there are several options to
manage water productivity in these systems [32].
Water at present is considered a free or low-cost resource
in most parts of the world [34]. This needs to be revisited
for protecting this crucial ecosystem service. Water pri-
cing is likely to play a key role as part of water man-
agement policies. It could improve water productivities as
water would be used more sparingly, but it is necessary
that water pricing policies do not affect the poor by
limiting further their access to this resource. At the same
time, paying ecosystems services payments to livestock
farmers to protect water sources could also be part of the
solution in certain places. Meeting the demand for live-
stock products under alternative water price scenarios is
an area that also requires significant research.
Livestock and climate change
The linkages between livestock and climate change are
two-way and dynamic. On the one hand, climate change
has significant impacts on several aspects of livestock
production such as feed quantity and quality, animal
and rangeland biodiversity, distribution of diseases, man-
agement practices and production systems changes and
others. Significant adaptation will need to occur in differ-
ent production systems to cope with these changes. Read-
ers are referred to recent reviews [35
,3638] that deal
with these aspects in detail. On the other hand, livestock
have impacts on climate change through emissions of
greenhouse gases.
Livestock contribute to 18% of global anthropogenic
GHG emissions [6
]. The main sources and types of
greenhouse gases from livestock systems are CO
land use and its changes (feed production, deforestation)
and N
O from manure and slurry management that
account for 32% and 31% of emissions from livestock,
respectively. This is followed by methane production
from ruminants, which accounts for 25% of emissions.
Large differences in GHG emissions exist between differ-
ent regions. The climate change impacts of livestock
production have been widely highlighted, particularly
those associated with rapidly expanding industrial live-
stock operations in Asia and those linked to deforestation
(feed production, pasture expansion) in Latin America.
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However, livestock are not bad everywhere. In smallholder
croplivestock and agro-pastoral and pastoral livestock
systems, livestock are one of a limited number of broad-
based options to increase incomes and sustain the liveli-
hoods of people who have a limited environmental foot-
print. GHG emissions from livestock and their impacts are
relatively modest when compared with the contribution
that livestock make to the livelihoods of hundreds of
millions of poor people. This complex balancing act of
resource use, GHG emissions and livelihoods requires
better understanding. Weighting the environmental
impacts vis-a
`-vis the social benefits is a subject that
deserves significant new research, methodologies, and
indicators to inform the debate more accurately. The same
applies to the comparison of GHG emissions (total and per
unit of output) between systemsof different intensification
level and between sectors. Life cycle and value chain
analysis could play a significant role in this regard [39,40].
Mitigating greenhouse gases from livestock
Meeting the demand for livestock products in future
carbon-constrained markets will require a mixture of
adaptation and simple, effective and transparent mitiga-
tion strategies. According to Smith et al. [41] three differ-
ent ways to contribute to reduction in GHG exist: direct
reductions of GHG, removing CO
from the environ-
ment, and offsetting emissions through indirect effects.
Livestock can contribute to these in the following ways.
Reducing GHG emitted by livestock systems
Managing the demand for livestock products: As mentioned
before, managing the demand for livestock products in
terms of reductions of consumption of livestock products
in the developed world and sustainably intensifying sys-
tems in the developing world to produce more livestock
products per unit of methane can be part of the solution.
This needs to be accompanied by adequate regulations,
incentives and policies [6
] and possible carbon quota-
s.Intensification of the diets of animals: This is an area that
has enormous scope because a significant reduction in the
amount of methane produced per unit animal product is
possible by increasing the quality of the diets of rumi-
nants [42]. This increased efficiency could be achieved
through improved land use management with practices
like improved pasture management (grazing rotation,
fertilizer applications, development of fodder banks,
improved pasture species, use of legumes, etc.) and
supplementation with crop-by products and others. Other
options include manipulation of rumen microflora, and
use of feed additives [35
Control of animal numbers and shifts in breeds: animal
numbers is possibly one of the biggest factors contribut-
ing directly to GHG emissions from livestock [43]. In the
developing world, a large number of low-producing
animals could be replaced by fewer but better fed animals
of higher potential to be able to reduce total emissions
while maintaining or increasing the supply of livestock
products. These kinds of efficiency gains will be essential
in carbon-constrained markets.Shifts in livestock species:
switching species to better suit particular environments
is a strategy that could yield higher productivity per
animal for the resources available. At the same time,
switches from ruminants to monogastrics could lead to
the reduced methane emissions, though this could
increase the demand for grains in places thus increasing
production from land use changes and N
O from
manure manangement. This trade-off needs to be closely
assessed. Alternative feeds and feeding practices for
monogastrics should be the subject of considerable
research to reduce these trade-offs.
Reducing GHG from manure management: Reducing GHG
from manures can be achieved through nutritional man-
agement [44] and better handling and storage of manure
[28], for example. Reductions of 30% of emissions from
manure could be obtained through existing technologies
in Europe [28]. Regulations and incentives are also
required to reduce N2O emissions from manures. These
are of particular importance for managing excreta in the
developing world and for slurry and manure applications
in the developed world.
Livestock systems and carbon sequestration
Significant amounts of soil carbon could be stored in
rangelands or in silvopastoral systems through a range
of management practices suited to local conditions. This
not only improves carbon sequestration but could also
Livestock, livelihoods and the environment: understanding the trade-offs Herrero et al. 117
Table 3
Potential for carbon sequestration (Tg C/yr) in global rangelands of different overgrazing severity, by Continent (Conant and Paustian
Light Moderate Strong Extreme Total
Africa 1.9 8.6 6.1 0.1 16.7
Australia/Pacific 4.5 0.1 0.0 4.4
Eurasia 0.8 3.2 0.3 4.3
North America 0 1.6 0.6 2.2
South America 6.1 11.3 0.7 0.4 18.1
Total 13.3 24.4 7.4 45.7 Current Opinion in Environmental Sustainability 2009, 1:111120
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turn into an important diversification option for sustaining
livelihoods of smallholders and pastoralists through pay-
ments for ecosystems services. The potential for carbon
sequestration from global degraded rangelands is approxi-
mately 45 Tg C/yr, with the highest potentials in Africa
and Latin America (37% and 40% of potential global
rangeland C sequestration, respectively) [45
(Table 3). Average rates of C sequestration is this study
were 0.18 Mg C/ha/yr [45
While technical options for mitigating emissions from
livestock in developing countries exist, there are various
problems to be overcome, related to incentive systems,
institutional linkages, policy reforms, monitoring tech-
niques for carbon stocks, and appropriate verification
protocols, for example. For the pastoral lands, Reid
et al. [46] conclude that mitigation activities have the
greatest chance of success if they build on traditional
pastoral institutions and knowledge, while providing pas-
toralists with food security benefits at the same time.
Livestock systems and GHG emission offsets
Crops and residues from agricultural lands can be used as
a source of fuel, either directly or after conversion to fuels
such as ethanol or diesel. While these bio-energy feed-
stocks still release CO
upon combustion, the carbon is of
recent atmospheric origin (via photosynthesis), rather
than from fossil carbon. The net benefit of these bio-
energy sources to the atmosphere is equal to the fossil-
derived emissions displaced, less any emissions from
producing, transporting, and processing. CO
can also be avoided by agricultural management practices
that forestall the cultivation of new lands now under
forest, grassland, or other non-agricultural vegetation
[41]. At the same time, biogas from manures can be used
to offset energy use in livestock systems.
Livestock and biodiversity
Livestock have widespread direct and indirect impacts on
biodiversity, which is defined as the number and diversity
of genes, species, populations, and ecosystems. These
impacts are principally negative, although there are some
positive impacts as well, and they affect every square km
of Earth—on land, in the sea, and throughout the atmos-
phere. Overall, biodiversity loss through livestock is dri-
ven by the increasing demand and consumption of milk,
meat, and eggs, which leads to a greater need to grow
crops and harvest fish to feed livestock [6
]. Livestock
negatively affect biodiversity through heavy grazing on
plants and soil compaction; forest loss when pastures and
cropland expand to grow livestock feed in the tropics
], often driven by long-distance trade in feeds; emis-
sions of greenhouse gases that cause climate change and
then affect biodiversity; diseases spread by livestock to
wildlife; simplification of landscapes through intensifica-
tion and fragmentation [14]; competition of livestock with
wildlife; pollution of watercourses with nutrients, drugs,
and sediments, with related effects on aquatic biodiver-
sity; native biodiversity loss through competition with
non-native feed plants; and overfishing to create fishmeal
for livestock [47
]. Positive impacts occur when livestock
production is more efficient, where fewer natural
resources are used for each kilogram of milk, meat, or
eggs produced [48]; moderate grazing increases species
diversity; and pastoral land use protects wildlife biodi-
versity in savannah landscapes [49].
While livestock have many direct impacts on biodiversity
through trampling, grazing, and defecation, the larger
impacts may be indirect—through deforestation to create
pastures; emissions of methane and other greenhouse
gases; the growing feed trade; and the pollution of
streams, rivers, lakes, and oceans [47
]. Effects on marine
systems are multiple and unexpected [50], through fish
harvest for fishmeal, coral loss through climate change,
introduction of marine invasion species, and probably
dust-transmitting pathogens reaching coral reefs.
There is a large body of evidence that suggests that
livestock and environmental trade-offs are currently sub-
stantial and that these will increase significantly in the
future as a result of the increased demand for livestock
products from the growing population. Some of the most
important impacts are those associated with land use
change for feed production both for ruminants and mono-
gastrics, which have significant simultaneous impacts on a
range of environmental dimensions (land use, GHG,
water cycles, nutrient balances, biodiversity).
At the same time, there seem to be significant opportu-
nities in livestock systems for improving environmental
management while improving the livelihoods of poor
people. Sustainable intensification of smallholder systems
could offer promising alternatives in highly populated
areas of the developing world, while there is strong
evidence that rangelands can sequester significant
amounts of carbon and can play an important role in
improving the water productivity of whole ecosystems
in certain places. These strategies, though potentially
difficult to implement, require substantial research to
verify their feasibility.
There is a need for a fundamental shift in the way we see
demand for livestock products and in the way different
production systems can respond to meet this demand.
Demand for livestock products needs to be reduced in
places where there is excessive consumption of animal
products or in places where environmental impacts are
currently or potentially severe. At the same time, there is
a need to simultaneously de-intensify certain systems
through policies and payments for ecosystems services,
while other systems that might have been neglected in
the past intensify via technologies that can improve
118 Inaugural issues
Current Opinion in Environmental Sustainability 2009, 1:111120
Author's personal copy
efficiency gains to produce more product per unit of
resource. We need to provide significant incentives so
that the marginal rangeland areas often rich in biodiver-
sity can be protected and farmers can benefit from these.
There is a subtle balancing act for achieving this and it
needs commitment from the science community, policy
makers and other stakeholders if livestock are going to
continue having a significant role in the livelihoods of
millions of people around the world.
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120 Inaugural issues
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Full-text available
Where the river basin is generally seen as the appropriate unit for analysing freshwater availability and use, this paper shows that it becomes increasingly important to put freshwater issues in a global context. International trade in commodities implies flows of 'virtual water' over large distances, where virtual water should be understood as the volume of water required to produce a commodity. Virtual water flows between nations have been estimated from statistics on international product trade and the virtual water content per product in the exporting country. With increasing globalization of trade, global water interdependencies and overseas externalities are likely to increase. At the same time liberalization of trade creates opportunities to increase physical water savings.
Full-text available
Private lands in the American West are undergoing a land-use conversion from agriculture to exurban development, although little is known about the ecological consequences of this change. Some nongovernmental organizations are working with ranchers to keep their lands out of development and in ranching, ostensibly because they believe biodiversity is better protected on ranches than on exurban developments. However, there are several assumptions underlying this approach that have not been tested. To better inform conservation efforts, we compared avian, mesopredator, and plant communities across the gradient of intensifying human uses from nature reserves to cattle ranches to exurban developments. We conducted surveys at randomly selected points on each type of land use in one Colorado watershed between May and August of 2000 and 2001. Seven bird species, characterized as human commensals or tree nesters, reached higher densities ( all p < 0.02 ) on exurban developments than on either ranches or reserves. Six bird species, characterized as ground and shrub nesters, reached greater densities ( all p < 0.015 ) on ranches, reserves, or both of these types of land use than on exurban developments. Domestic dogs ( Canis familiaris ) and house cats ( Felis catus ) were encountered almost exclusively on exurban developments, whereas coyotes ( Canis latrans ) were detected more frequently ( p = 0.047 ) on ranchlands than exurban developments. Ranches had plant communities with higher native species richness and lower non-native species richness and cover than did the other types of land use ( all p < 0.10 ). Our results support the notion that ranches are important for protecting biodiversity and suggest that future conservation efforts may require less reliance on reserves and a greater focus on private lands.
Full-text available
1] Excessive grazing pressure is detrimental to plant productivity and may lead to declines in soil organic matter. Soil organic matter is an important source of plant nutrients and can enhance soil aggregation, limit soil erosion, and can also increase cation exchange and water holding capacities, and is, therefore, a key regulator of grassland ecosystem processes. Changes in grassland management which reverse the process of declining productivity can potentially lead to increased soil C. Thus, rehabilitation of areas degraded by overgrazing can potentially sequester atmospheric C. We compiled data from the literature to evaluate the influence of grazing intensity on soil C. Based on data contained within these studies, we ascertained a positive linear relationship between potential C sequestration and mean annual precipitation which we extrapolated to estimate global C sequestration potential with rehabilitation of overgrazed grassland. The GLASOD and IGBP DISCover data sets were integrated to generate a map of overgrazed grassland area for each of four severity classes on each continent. Our regression model predicted losses of soil C with decreased grazing intensity in drier areas (precipitation less than 333 mm yr À1), but substantial sequestration in wetter areas. Most (93%) C sequestration potential occurred in areas with MAP less than 1800 mm. Universal rehabilitation of overgrazed grasslands can sequester approximately 45 Tg C yr À1 , most of which can be achieved simply by cessation of overgrazing and implementation of moderate grazing intensity. Institutional level investments by governments may be required to sequester additional C.
Cycling of potassium in grassland systems has received relatively little attention in research and practice in recent years. Balanced nutrient systems require consideration of nutrients other than nitrogen (N). Potassium (K) is needed in large amounts and is closely related to N nutrition. In intensive dairy farming, surpluses of K arise from the input of concentrates and fertilizer and are returned to the grassland and may lead to increasing K content in the soil. Organic farming, on the other hand, is characterized by limitations in input of nutrient sources and quantities. Leaching of K from grassland is usually low, but high levels of available soil K, high K input from fertilizer or at urine patches lead to increasing losses. High K inputs have a negative influence on Mg and Ca uptake by plants and can cause accelerated leaching of these cations. High levels of K have been associated with inducing nutrition-related dairy cow health problems such as milk fever (hypocalcaemia) and grass tetany (hypomagnesaemia). This review gives an overview of the cycling of potassium and related cations in grassland systems especially with regard to leaching losses and identifies limitations to knowledge.
Climate change associated with greenhouse gas (GHG) emissions may have important implications for Europe's grasslands. Projected scenarios indicate that increased temperatures and CO2 concentrations have the potential to increase herbage growth and to favour legumes more than grasses, but changes in seasonal precipitation would reduce these benefits particularly in areas with low summer rainfall. Further implications for grasslands may arise from increased frequency of droughts, storms and other extreme events. Potential farm-scale adaptive responses to climate change are identified. Grassland agriculture also contributes to GHG emissions, particularly methane and nitrous oxide, and management of grassland affects net carbon balances and carbon sequestration. Management options are identified for mitigating grassland's contribution to GHG emissions which need to be developed in a holistic way that also considers other pressures.