Where & how it happens

Previous section The environmental challenges

Livestock can damage land and vegetation in a number of different ways but there are also many examples of environmental balance and positive contributions. Livestock interact with land (which includes soil and vegetation), water, air, and plant and animal biodiversity. About 34 million km2 or 26 percent of the world's land area is used for grazing livestock. In addition, 3 million km2, or about 21 percent of the world's arable area is used for cereal production for livestock feed. Livestock produce approximately thirteen billion tons of waste. A large part of this is recycled but, where animal concentrations are high, waste poses an enormous environmental hazard. Livestock grazing can affect the water balance in certain areas. Water is needed for fodder and feed concentrate production, as drinking water for animals, and to drain surplus waste and chemicals. Livestock interact directly and indirectly with biodiversity; while often biodiversity is compromised there are also examples of mutual benefits. Livestock, and livestock wastes, cause gaseous emissions with important local and global impact on the environment.

"Hot Spots" of livestock-environment interactions

Fig 2.1 Total meat production from different production systems.

For a large part, livestock interact with the environment within the confines of a production system. These production systems are evolutionary responses to population pressure, resource endowment and marketing opportunities. Three main production systems are distinguished (Seré and Steinfeld, 1996): grazing, mixed farming and industrial systems. Grazing systems are mainly based on native grassland, with no or only limited integration with crops. These systems rarely involve imported inputs and generally have a low calorific output per hectare (Jahnke, 1982). In mixed farming systems, livestock and crop activities are integrated. For agriculture as a whole, this has been the main avenue for intensification. As by-products (crop-residues, manure) of one enterprise serve as inputs into the other, this system can be environmentally friendly. Industrial production systems are detached from immediate land in terms of feed supply and waste disposal. Where the demand for animal products increases rapidly, land-based systems fail to respond and lead to animal concentrations which are out of balance with the waste absorptive and feed supply capacity of the land.

Grazing and overgrazing

About 34 million km2 or 26 percent of the world's land area is used for grazing livestock.

Grazing animals can improve soil cover by dispersing seeds with their hoofs and through manure, while controlling shrub growth, breaking up soil crusts and removing biomass which otherwise might provide fuel for bush fires. All these impacts stimulate grass tillering, improve seed germination and thus improve land and vegetation. On the other hand, heavy grazing causes soil compaction and contributes to erosion, and decreases soil fertility, organic matter content and water infiltration and storage.

The arid rangelands with a vegetation period of less than 90 days have generally been associated with widespread degradation. Several authors (Dregne et al., 1992, WRI, 1992) argued that the majority of the world's rangelands are moderately or severely desertified. UNEP (ISRIC/UNEP, 1991), estimates that, since 1945, about 680 million hectares or 20 percent of the world's grazing lands show significant soil degradation.

However, if irreversibility and declining productivity are taken as the main characteristics of degradation (Nelson, 1990), then the actual situation of the world's arid grass and rangelands is better than generally reported. For example, in the Sahel, animal production per head and per hectare has improved, rather than declined over the last three decades (see Box 2.1). This has occurred in spite of a large increase in the number of livestock, and a decrease in the area of rangelands. This surprising increase in productivity confirms the findings of NASA (Tucker et al., 1991), which show vegetation at the same northern limits as before the big droughts of the seventies and eighties. They point to a fluctuating pattern, or a "contracting and expanding Sahara" rather than a continuously expanding desert.

Box 2.1 Productivity trends in the Sahel.
An analysis of livestock production in five Sahelian countries over a thirty year period, carried out as part of this study, shows a 93 percent increase in the meat produced per ha, and 47 percent increase in the meat produced per head. At the same time, there was a 22 percent increase in the animal population (from 14.5 to 17.6 million TLU1 ) over the same period. This productivity increase occurs in both cattle and small ruminants. Part of the increased productivity might result from the progressive move of the livestock population from the arid to the more humid areas, and the increased use of crop residues. However, a part from the sharp inter-annual variation, the long term trend points to a rather sustained productivity, and obvious stable resource base.
Source: Analysis carried out under this study, based on FAO-WAICENT data.
1 Burkina Faso, Chad, Mali, Niger, Senegal and Sudan

In the light of this evidence, the arid rangelands are now seen as containing dynamic and highly resilient ecosystems, especially under traditional management of continuous adjustment to the highly variable rainfall (both in time and space). Arid vegetation is extremely resilient and most of the changes observed are the result of particularly dry spells and are therefore likely to be temporary. The decrease in woody and perennial species observed over the last decades in the Sahel (Boudet et al., 1987) is likely to be the result of recent droughts. Resting an area brings the original flora back again (Hiernaux, 1996), which indicates that the loss of these species is not irreversible. In effect, in an extensive review of grazing and production data of 236 sites worldwide, including many sites in the arid zone, it was shown that there was no difference in biomass production, species composition and root development in response to long term grazing in the field (Milchunas and Lauenroth, 1993). The continuous "dis-equilibrium 2" conserves land, especially in the annual vegetation of the more arid areas, as the low pressure after a drought facilitates recuperation and, although with a time lag, overall grazing pressure is adjusted to the amount of feed available. Flexibility and mobility are therefore key requirements to achieve sustainable rangeland use in these areas.

2 The theoretical bases for range management under those conditions have recently been well described by Behnke, Scoones and Kerven (1993) and Scoones (1995).

Where this mobility is impaired and customary practice impeded by changing property rights, degradation often occurs. The nationalization of arid rangelands which was introduced by many governments in the post colonial period in Africa and Asia, undermined the intricate fabric of customary practice by replacing an ecologically well balanced system of communal land use with a "free for all" open access system. The deterioration of common property resources has been documented by Jodha (1992) for India. Here, the area under common property not only decreased by as much as 30 to 50 percent over 30 years but was also accompanied by significant degradation caused by the erosion of traditional institutions and informal obligation of common resource maintenance. Policies to "settle" the pastoralists, to promote ranches and regulate stocking rate, which were major principles of arid rangeland development of the 1960s and 1970s, reduced the critical mobility and flexibility in that system, and tied down stock to graze limited areas which might have received little rain. In the Middle East and Central Asia, state farms are being privatized and cut up, thereby impeding pastoralists' mobility.

The development of water points for human and livestock use often open up arid lands and cause land degradation. Around the water points, bare surfaces are caused by animal trampling. The degraded land typically accounts for 5 to 10 percent of the total area. Normally, soil fertility is quite high but normal vegetation patterns are impeded by the impact of hoofs, including soil compaction, and heavy grazing. Long term studies in Senegal and Sudan (Thomas and Middelton, 1994) did not find a significant expansion of the sacrifice areas of individual water points in these countries. More importantly, water development in the arid areas might upset entire ecosystems by changing the relationship between traditional wet and dry season grazing areas, and converting traditional dry season grazing into year-round grazing.

In the semi-arid zones, those with more than 90 days' growing seasons, land degradation through grazing livestock is much more serious than at the fringes of the desert, and this is where the main livestock-environment hot-spot is to be seen. Data from a transect in Mali showed that land degradation in the 600-800 mm rainfall areas was significantly greater than in the 350-450 mm rainfall area. In the higher rainfall area, the percentage of barren soil increased from zero to 10 percent over the period 1950-1990 whereas in the arid areas there was no significant change. A similar situation is reported in parts of North Africa and the Middle East (Sidahmed, 1996), although quantitative data are not available.

Box 2.2 How rational are pastoralists?
The perception that pastoralists maintain unproductive animals in their herds for "prestige" rather than economic reasons, is still widespread. This, in the eyes of many, is one of the main reasons for overstocking and land degradation. However, almost all studies on pastoral and agro-pastoral systems show that there are very few unproductive animals in traditional herds (ILCA, 1994). Animals are sold when they have their optimum market weight. Unproductive animals are sometimes found in "investments herds" owned by traders or civil servants who, in the absence of reliable and remunerative banking systems in sub-Saharan Africa, invest in livestock.

This degradation is linked to the growing population in these areas. Crop encroachment, fuelwood collection and overgrazing are the interlocking factors causing land degradation in the semi-arid zones. Crop encroachment not only exposes the soil directly to the erosive effects of winds and downpours, it progressively hampers the flexibility of animal movement because it obliterates passages between wet and dry season grazing areas. Fuel and fertilizer subsidies, especially in the Middle East and North Africa, often exacerbated the conversion of the higher potential sites within arid rangelands into marginal crop land. Drought emergency programmes, which handed out subsidized concentrate feed, probably also contributed to range degradation, allowing too many animals to be maintained on the range, and preventing an ecologically normal regeneration of the range vegetation after the drought. These feed subsidies have now become a structural phenomenon, especially in North Africa and the Middle East, leading to continuous growth of the livestock population which are no longer constrained by poor pasture productivity in these low rainfall regions.

While data on the effect of grazing on water infiltration are site specific, the picture emerges that light to moderate grazing can improve or maintain infiltration, whereas heavy grazing almost always reduces it. Long term observations on the Edwards Plateau in Texas have shown that both heavy grazing and no grazing caused lower infiltration and higher erosion rates than moderately grazed pastures (GMS, 1996).

Complementarities can be observed between wildlife and livestock. There is increasing evidence that the combination of wildlife and livestock can result in greater biodiversity and a higher income for pastoralists and ranchers. Usually, livestock-wildlife combinations do not require significant reductions in livestock stocking rates. For example, a reduction of only 20 percent of the cattle stocking rate is estimated to be required to create the "niche" for most wildlife species to prosper (Western, personal communication). Others estimate (Byrneet al., 1996) a larger dietary overlap, and thus the need for a greater reduction, but all agree that there is substantial complementarity. There is also fairly general agreement that wildlife ranching on the basis of meat alone is not financially viable. Game meat is now attractive because it occupies a "niche market".

Environmental degradation in semi-arid zones also occurs as water pollution by agrochemicals used for the control of livestock disease "vectors" such as ticks (carriers of many diseases, such as Anaplasmosis and East Coast Fever), tsetse flies (carriers of the African Sleeping Sickness in man and animals) and weeds. Ticks have been controlled traditionally by cattle dips or sprays using organo-chlorines. Fauna has been damaged both by inappropriate dosing (which has led to increased resistance of ticks) as well as by inappropriate drainage (which has led to used dip being discharged to open water). Herbicides and other pesticides have frequently been used in the industrialized world although the amount used on range and grasslands is minimal. For example, only one percent of the rangelands in Texas is treated with herbicides (GMS, 1996).

For the temperate climates, the main concern is the impact of grazing on biodiversity in stream riparian areas, which account for about 5 percent of the total grazing area in these zones. Such stream sides typically receive 20-30 percent more grazing animals (GMS, 1996), and cattle in particular can thus influence the water quality (increased nitrates and phosphates), as well as plant and animal biodiversity of land and aquatic systems (GMS, 1996). In such riparian areas sheep have been shown to have a smaller impact on plant communities and stream pollution. These areas require special attention, site specific mitigative actions and the use of appropriate livestock species.

Livestock and deforestation

Table 2.1 Annual deforestation 1980-1990 (million ha and percent) in different regions of the world.
Region | Annual change in area (m.ha) | Annual rate of change (%) | Remaining forest area (1990) (m.ha)
Latin America | 1.9 | 0.4 | 454
Africa | 0.5 | 0.5 | 86
Asia | 2.2 | 1.1 | 177
Source: FAO, 1994.

Tropical rainforests cover about 720 million ha. and contain approximately 50 percent of the world's biodiversity. Since 1950, more than 200 million hectare of tropical rainforests were lost, with various contributing factors, including ranching and crop cultivation and forest exploitation. Ranching-induced deforestation is one of the main causes of loss of some unique plant and animal species in the tropical rainforests of the Americas, one of the world's richest sources of biodiversity. These rainforests are estimated to contain 50 percent of the world's plant and animal species (World Commission on Environment and Development, 1987). Since 1950, the area in Central America under pasture has increased from 3.5 million to 9.5 million hectares, and cattle populations have more than doubled from 4.2 million to 9.6 million head over the same period (Kaimonitz, 1995). On the other hand, in Asia and Africa deforestation is mainly the result of crop expansion.

In the humid tropics, forest and savanna clearing to establish pastures for ranching causes soil nutrients to leach out rapidly. Weeds displace grasses, and artificial pastures can only be sustained for a period of up to ten years. More than 50 percent of the pasture areas in the Amazon area has now been abandoned in a degraded state. Natural regeneration of forests is quite difficult, especially in large areas. Under good management and using modern technology, however, the establishment of pasture and the introduction of cattle can be the "second best" in maintaining soil fertility. For example, CIAT (1994) developed a sustainable land management system, using grass and nitrogen-fixing legumes.

Table 2.2 Some estimates of the main causes of deforestation (percent of total deforestation).
Region | Crops | Livestock | Forest exploitation
South America | 25 | 44 (70in Brazil) | 10
Asia | 50 - 60 | Negligible (Philippines & Indonesia to some extent) | 20
Africa | 70 | Negligible | 20
Source: Bruenig, 1991.

Land speculation, titling procedures and governments providing financial incentives have been the main reasons for ranch-induced deforestation (Kaimonitz, 1995). Land speculation is heavily influenced by road construction, because land prices are closely correlated to the distance to an all-weather road. In many countries, land titling procedures still require that the land is under agricultural use before a title can be given. Such procedures, of course, encourage deforestation. Incentive policies, in the late '60s and '70s which provided subsidized interest rates with lenient reimbursement conditions and beef export subsidies, have played an important role in ranch expansion. They have been phased out, and this has stopped investment in large ranches by absentee owners. This is reflected in the decline in the deforested area. In Central America in the 1980s, rainforest disappeared at an annual rate of 430,000 hectares per year. This had declined to 320,000 hectares over the period 1990-1994, although this should be seen in the perspective of only about 19 million hectares remaining in 1990. Current ranch-induced deforestation is mainly caused by smallholders, who have no other means to sustain themselves, and who have to "slash and burn" new areas because the current system of pasture establishment and management is not sustainable.

Crop-livestock interactions: intensification and involution

The integration of crop and livestock still represents the main avenue for intensification of food production. Mixed farming provides farmers with an opportunity to diversify risk from single crop or livestock production, to use labour more efficiently, to have a source of cash and to add value to low value or surplus feed. To varying extents, mixed farming systems allow the use of waste products of one enterprise (crop by-products, manure) as inputs to the other enterprise (as feed or fertilizer). Mixed farming is, in principle, beneficial for land quality in terms of maintaining soil fertility. In addition, the use of rotations between various crops and forage legumes replenishes soil nutrients and reduces soil erosion. (Thomas and Barton, 1995).

Adding manure to the soil increases the nutrient retention capacity (or cation exchange capacity), improves the physical condition by increasing the water-holding capacity and improves soil structure stability. This is a crucial contribution because, in many systems, it is the only avenue available to farmers for improving soil organic matter. It is also substantial in economic terms. Approximately 20 million tons or 22 percent of total nitrogen fertilization of 94 million tons (FAO, 1997) and 11 million tons or 38 percent of phosphate is of animal origin, representing about US$ 1.5 billion worth of commercial fertilizer. Not only does animal manure replenish soil fertility but it helps to maintain or create a better climate for soil micro-flora and fauna. It is also the best way of using crop residues.

However, mixing crops and livestock neither generates new nutrients (with the exception of nitrogen fixation by leguminous plants) nor reduces nutrient surpluses. But livestock, even in situations of low technological levels allow for 1) the spatial and temporal allocation of nutrients from areas of lower returns from cropping to those with higher returns; 2) the acceleration of nutrient turnover in the production cycle; and 3) the reduction of nutrient losses within the cycle compared to agricultural production without livestock.

Thus, the key issue is the nutrient balance. Most mixed farming systems of the developing world have a negative nutrient balance. Deficits are partially covered by a flow of nutrients from (often communal) grazing areas to cropland. As population pressure changes the crop/grazing land ratio, and if other sources are not available, fertility gaps widen. This is typically the case of many mixed farming systems in the tropics. Reported deficits ranged from about 15 kg N/ha/year in Mali, to more than 100 kg N/ha/year in the highlands of Ethiopia (de Wit et al., 1996). The result is that crop yields continue to decline. This can lead to increased competition for land and grazing resources which, in turn, can lead to privatization of crop residues, or of the rangelands. Resource degradation, property and population pressure carry a high risk of conflict as the recent events in Rwanda have proven.

However, positive trends, intensifying and diversifying production also occur. A key factor facilitating such positive trends is access to markets as illustrated by the Machakos case study in Kenya. (see Box 2.3). This development path has the biggest potential in Latin America and sub-Saharan Africa, where, in most areas, land is not a limiting factor and integrated crop-livestock systems have the immense potential to contribute to the required productivity growth. However, in the intensive production systems of the tropical highlands, soil erosion problems become critical but, here also, livestock can play a positive role. For example, in Ethiopia losses from poorly managed sloping terraces under crops and degraded rangelands amount to between 20 and 100 MT/ha/year, whereas well managed pastureland loses between 0-7 MT/ha/year and well managed forest land loses between 0-10 MT/ha/year (Bojo and Cassells, 1995).

Box 2.3 Positive effects of intensification: The Machakos case.
Human pressure and intensification can also work positively. English et al., (1992) showed, that in the semi-arid Machakos district in Kenya the natural resource base improved despite a 500 percent population growth over the last 60 years, an increase of cropland from 35 percent of the higher potential area in 1948 to 81 percent in 1992, and an increase of the livestock population per farm from 5.4 Animal Units in 1940 to 16.2 in 1980. Dynamic market development made farming profitable, and off-farm employment generated enough capital for investments in soil and water conservation. Horticulture and smallholder dairy production are the main activities generating the cash for resource conservation. The famine predicted in the 1930's for the Machakos district never occurred.

Animal draught is still a main component of many smallholder farms in developing countries, substituting for human labour and drudgery. An estimated 250 million working animals provide the draught power to approximately 28 percent of the world's arable land, equivalent to 52 percent of total cropping land in developing countries. In southeastern and east Asia, animal draught is decreasing in importance as rapid mechanization takes place. By contrast, many areas in Africa are developing into mixed farming with draught animals playing a key role in providing tillage for crop area expansion and yield increases. As a renewable form of energy, animal draught substitutes for fossil energy and the use of other natural resources.

For the mixed farming systems, livestock provides the economic justification for maintaining a mosaic of land use patterns. Agroforestry inputs such as rows of fodder trees and grass bands are widely known in terms of controlling wind and water erosion and therefore conserving biodiversity. An often overlooked component of this biodiversity is soil micro-flora and fauna. Arthropods, with 90 percent of all species, dominate biodiversity (Pimentel 1991) and are found throughout forested and agricultural areas. In a New York alfalfa "ecosystem" Pimentel reported 600 species of above ground arthropods. Mixed farming systems and the use of manure, which bring about an increase in the organic matter of the soil, enhance soil micro-flora and fauna.

Past policies have often limited the synergistic effect of crops and livestock in nutrient deficient situations. Imposing high import duties to protect domestic cereal production pushed cropping into marginal areas and upset the equilibrium between crops and livestock. Poor land tenure security, especially in the rainfed mixed farming systems of the developing world, has provided a disincentive for investment in long-term soil fertility improvements, such as the use of inorganic fertilizers and the use of green manure and leguminous fodder crops in the crop rotation.

In many places of the world, subsistence farms with crops, livestock and household closely interlinked ("closed circuit" farms) have developed and continue to be a predominant feature. With human population pressure increasing further, the need for intensification brings livestock more and more into cropping areas and integrates them in nutrient and energy cycles. Almost throughout the world the family-based and diversified mixed farming system has come under pressure either from novel technologies and market forces or from resource degradation and poverty. Two major features emerge: One scenario leads to specialization where market forces and technological requirements force mixed farming systems to grow in unit size and to specialize. With specialization, there are fewer opportunities for on-farm crop-livestock integration. The resultant environmental problems which result will be dealt with in the following chapter. Another significant trend is what has been described as "involution" , or collapse of the mixed farming system. In virtually all tropical highland areas the relatively high human population densities are traditionally sustained by rather complex, mixed farming systems. Population pressures may decrease farm sizes to a point where associated land pressures are no longer compensated by commensurate land productivity increases resulting in the disintegration of the system. Livestock, often large ruminants, can no longer be maintained on the farm. This results in a greater deficit of nutrients and energy, and leads to natural resource degradation and loss of investment.. There is mounting evidence that human population pressures, poverty and resource degradation, aggravated by lack of access to markets and employment opportunities, are cause-and-effect factors of the involution. (Himalayan hills, African highlands, Andean countries, Java).

This involution of previously well-integrated mixed farming is to be seen as another livestock environment "hot spot". Here, it is not the interaction between livestock and natural resource that creates a degradation problem but rather the socio-economic context that lead to a diminishing interaction which eventually ceases altogether.

Livestock and nutrient surplus

Excess soil nutrients, which are a result of net nutrient imports, exist in large areas of northwestern Europe (the Netherlands, Germany, and Brittany in France), in the eastern and midwestern USA and Japan. These areas are generally located near ports (in order to benefit from low transport prices), and near large urban areas (to benefit from low transport costs of milk and meat). In OECD countries, nutrient excess situations are increasingly regulated, alleviating some of the environmental hazard, particularly in extreme situations such as the Netherlands. By contrast , in most developing countries, in particular pig and poultry production in Asia, lack of regulations and weak infrastructures allowed a surge of peri-urban production. Industrial livestock production emerges where the demand for animal products increases too rapidly for land-based systems to respond. This creates a vacuum which draws livestock into land-detached industrial systems. Because of weak infrastructure and therefore, high transport costs, these systems are usually found close to urban centres. Industrial production which is based exclusively on external inputs, bears enormous pollution problems and associated human health risks. Animal concentrations are out of balance with the waste absorptive and feed supply capacity of the land and, because of pollution and health hazards, most industrial production is moved out of city boundaries as soon as infrastructure permits.

In areas of high animal concentrations, excess nitrogen and phosphorus leaches or runs-off into groundwater, damaging aquatic and wetland ecosystems. Tests in Pennsylvania have shown that about 40 percent of the tested soil samples from dairy-crop farms exhibited excessive phosphorus and potassium levels. Soils are saturated, and surplus nutrients are leached into surface water and pollute the environment (Bacon et al., Narrod et al., 1994). A similar scene is set in Brittany, France, where in the 1980s, one in eight counties had soils with nitrate levels of more than 40 mg/litre. Now all eight counties report similar nitrate levels (Brandjes et al., 1995), which can cause extensive damage to the region's aquatic systems. More generally, such nutrient surpluses may affect particularly valuable ecosystems such as those adapted to poor soil conditions, by allowing encroachment by flora and fauna which are adapted to fertile soils, therefore reducing overall biodiversity.

Industrial and specialized livestock production systems emit large quantities of waste, resulting in excessive loading of manure on the limited land areas within reasonable distances of the producers. Globally, pig and poultry industries produce 6.9 million tons of nitrogen per year, which is equivalent to 7 percent of the total inorganic nitrogen fertilizer production in the world. According to Bos and de Wit (1996), 44, 50 and 20 percent of the nitrogen excreted by pigs, broilers and laying hens respectively is lost before being applied to the land.

The return of nutrients to land-based systems via manure frequently causes problems due to high water content and high transport cost. While it is difficult to generalize, transport beyond 15 kilometres is often uneconomical. In addition, mineral fertilizers, frequently a cheaper and more readily available source of nutrients, reduce demand for nutrients from manure even further, turning the latter into "waste". Surveys in Brittany have shown that, while the manure nitrogen would suffice, farmers bought an additional 80-100 kg of nitrogen per hectare per year in inorganic fertilizer. At farm level, the type of management defines the environmental burden of this waste. At the regional level, the nutrient surpluses result from feed imports. With low levels of feed imports, such as prevailing in Denmark, almost all manure can be used on the farm. With large feed imports, such as in the Netherlands, regional imbalances emerge and transport costs become a critical issue.

These nutrient surplus situations yield also excessive amounts of heavy metals, which are contained in feed as growth stimulants (copper and zinc mainly), or simple pollutants (cadmium). If the addition to the soil of heavy metals exceeds crop uptake, this may affect soil flora and fauna, ultimately posing human and animal health risks (Bos and de Wit, 1996). Regulations to reduce the heavy metal content of animal feed are now in place in most OECD member countries.

Direct drainage of manure in to surface water and leaching from saturated soils is a feature associated with industrial systems. In areas with high livestock concentrations, such as the Netherlands and Brittany in France, but also in East Asia, the spreading of manure on land can lead to nitrogen leaching into water. Nitrates contaminate surface water, leading to high algae growth, eutrophication and damage to the aquatic and wetland ecosystems. Phosphates, although less mobile than nitrates, can cause similar problems.

In the past, industrial systems have greatly benefited from policy distortions which, in many cases, have given these systems a competitive edge over land-based systems. In the EU, high domestic prices for beef and milk and low import tariffs for cereal substitutes, such as cassava meal, have encouraged intensive production systems and the creation of nutrient surplus situations. In the former centrally planned economies, beef feedlots were based on heavily subsidized feed grain and on subsidized fuel and transport. In many developing countries there are not only direct subsidies on feed but also on energy. With energy being a major direct and indirect cost item in industrial production systems, economy-wide policies often tend to favour them over their land-based counterparts.

Waste from processing

Like waste from animal production, the processing of animal products results in environmental damage when it is concentrated and unregulated. This is the case in urban and peri-urban environments, particularly in developing countries. Slaughtering requires large amounts of hot water and steam for sterilization and cleaning. Therefore, the main polluting component is waste water. (Verheijen et al., 1996). The concentration of organic compounds in waste water leads to oxygen demand, usually expressed as biochemical oxygen demand (BOD). Waste water contains fat, oil, protein, carbohydrates and other biodegradable compounds. Degradation of these organic substances requires oxygen. In addition, waste water usually contains insoluble organic and inorganic particles called suspended solids. In most developing countries, tannery effluent is sewered, discharged into inland surface waters or irrigated on the land (Verheijen et al., 1996). High concentrations of salt and hydrogen sulphide present in tannery wastewater greatly affect the water quality. Suspended matter such as lime, hair, fleshings, etc. make the surface water turbid and settle to the bottom, thereby affecting fish. Chromium tannin is toxic to fish and other aquatic life. When mineral tannery waste water is applied on the land, the soil productivity is adversely affected and some part of the land may become completely infertile. Due to infiltration, groundwaters are also adversely affected. Discharge of untreated tannery effluent into sewers causes deposition of calcium carbonate and blocks sewers. Discharge from dairies is often an issue in the developed world where the bulk of milk is factory-processed. In developing countries, home or village processing or consumption of processed milk is much more common. In Africa, it is estimated that 80-90 percent of milk is home processed or consumed raw whereas for Latin America, this share averages about 50 percent (FAO, 1990). Waste water production is the major environmental concern, mainly resulting from cleaning operations.

Waste water, mostly in large quantities, is one of the greatest environmental problems. The biodegradable organic compounds, suspended solids, nutrients and toxic compounds (particularly chromium and tannins from tanneries), result from a reduction of dissolved oxygen, into a deterioration or destruction of aquatic ecosystems. It also damages the quality of drinking water. Huge variations have been found, due to large differences in scale, in housekeeping and management practices of each factory or plant. The quantity of water used during processing is of major importance with high water use related to high emission values. In principle, the production of waste water does not necessarily lead to environmental problems if animal product processing is smallscale and not concentrated in a given area (Verheijen et al., 1996).

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