Global Impact of Livestock
Livestock are a major cause of alterations to global biogeochemical cycles
As the world’s largest user of land, livestock production has a huge footprint, affecting many components of the global environment. It uses vast areas of rangelands, and consumes one-third of the freshwater1 and one-third of global cropland as feed. Hence, the sustainability of the global food system is highly dependent on reducing the environmental footprint of livestock systems and on establishing sustainable levels of livestock-based food consumption. The challenge is great since the environmental consequences of livestock production has been largely neglected, including the lack of large-scale public health and epidemiological investigations into the disease patterns and public health threats of livestock. Threats and concerns over livestock production are increasing in developing countries: while the commerce and trade of livestock products in industrial countries is more than 50 % of total global agricultural output, in developing countries it accounts for about 33 % but its share is rapidly rising.
Environmental concerns regarding livestock production can be viewed as (i) concerns related to soils (accumulation of nutrients); (ii) concerns for water (eutrophication, pollution) and (iii) concerns for air (greenhouse gas emissions, odours, dust).
The direct and indirect impacts of livestock production on the global environment are wide-ranging, e.g.:
- deforestation to make way for additional farmland for feedstuffs, which requires intensive use of water, fertilisers, pesticides and fossil fuels;
- use of highly productive croplands to produce animal feedstuffs, which represents a net drain on the world’s potential food supply;
- pollution of surface and groundwater;
- habitat destruction, e.g. clearing and overgrazing;
- loss of biodiversity;
- impacts on human health via pathogens and harmful substances transmitted by livestock;
- alterations of global biogeochemical cycles, e.g. significant greenhouse gas emissions by livestock.
Impact on biogeochemical cycles
Crop-livestock production systems are the largest cause of alterations of the global biogeochemical cycles of nitrogen and phosphorus. Excretion of nitrogen and phosphorus by livestock can lead to various types of land degradation. For example, the excessive use of manure and fertilisers per hectare of land often leads to accumulation in soil and contamination of water resources through runoff and leaching. This is significant because the total amount of nitrogen and phosphorus in animal manure generated by livestock production exceeds global nitrogen and phosphorus fertiliser use. Generally, the enrichment of the environment leads to less biodiversity. The map shows one component of the nitrogen cycle – the excretion of nitrogen (as urine and faeces) associated with bovine meat production.
Landless livestock systems
In the past several decades the growing demand for livestock products, in concert with technological advances, has driven widespread changes in livestock production systems. These changes have radically affected the livestock production sector in both developed countries and parts of the developing world. One of the most significant changes has been a steady shift from grazing systems to landless livestock production systems. In fact, virtually all growth in livestock production is due to increases in industrialised landless systems.
Landless systems are not dependent on local land for crop production; rather, they are intensive, industrialised facilities where livestock are raised in high densities in stalls, pens and feedlots with a reliance on feedstuff obtained from external sources. Landless livestock farmers, which vary from smallholder farms to large-scale agribusiness, most often specialise in a single commodity, such as beef, dairy, pigs, poultry, etc. Overall, there has been rapid growth in the average size of livestock production units and a shift towards fewer and larger farms. Larger operations are better able to benefit from technical advances and economies of scale, such as improved genetics, compound (mixed or manufactured) feeds, especially in poultry and pig production.
While the majority of landless livestock systems are located in urban clusters of East Asia, South-East Asia, southern Brazil, Ecuador, central Mexico, eastern North America and Europe, by the year 2030 every developing region of the world (other than sub-Saharan Africa) will also produce more than half of its cattle and sheep in stalls, pens and feedlots.
Nevertheless, in spite of the shift towards landless production systems, livestock remains the world’s largest user of land. Unfortunately, the environmental and resource costs of feedstuffs and industrialised landless systems, which are often separated in space from each other, remain largely unaccounted for. This includes the persistent threat to the diversity of animal genetic resources.
Livestock and manure production
Globally, cattle (60 %) are the largest contributors to manure production, followed by pigs (9 %) and poultry (10 %). In extensive (or low-input) livestock systems, e.g. sub-Saharan Africa, manure is an important source of soil nutrients (carbon, nitrogen, etc.). Grazing and mixed-cropping systems tend to be closed systems where the waste products of one production cycle (especially manure, crop residues) are used as inputs to another.
This is in contrast to landless systems where there is a separation between livestock production and the land used to produce the feed, which can result in the production of large, concentrated quantities of animal waste products that threaten the environment and public health. Regardless of the livestock system, the recovery of nutrients from manure is highly variable and depends significantly on infrastructure and handling.
Importantly, the handling of manure, its storage and the synchrony of mineralisation with crop growth are main ways to increase nitrogen-cycling efficiencies in smallholder systems.
Manure production by bovines in the year 2000.
Source: M. Herrero, 2016.
Cattle in South America..
Source: J. Reynolds.