Where & how it happens

Previous section "Hot spots" of livestock-environment interactions

Global overlays

In addition to the livestock-environment "hot spots", there are a number of effects which go beyond those related to the different, and usually site-specific, livestock production systems. These global overlays may occur as a result of trade, as in the case of the environmental effects of feed production, or because the atmosphere is affected, as in the case of gaseous emissions, or because a common resource of the whole sector is concerned, as in the case of animal genetic resources.

Concentrate feed production

3 million km2, or about 21 percent of the world's arable area is used for the production of livestock feed, mostly concentrates (Hendy et al., 1995). For 30 years livestock production and productivity have been increased by feeding ever greater amounts of high quality feed. Pigs and poultry, the main users of concentrate feed, require diets with a high concentration of energy and protein; such high density feeds are also used in dairy production and beef feedlots. Because concentrate feed is tradable, decisions on feed production and use are often unconnected. In other words, decisions are made separately by different individuals at different places and times. In effect, trading these concentrates means trading the environmental impact. Worldwide, trading feed grain and other feedstuffs involves a massive transfer of nutrients, depleting the production resources, and fertilizing, and often polluting, the location of final use.

The production of concentrate feeds has an impact upon the natural resource base at various stages of crop production, trade and processing of feeds. Production affects land use through deforestation and change of habitats, and it has an impact upon biodiversity and aesthetic aspects of the landscape. In addition, there are direct effects of cropping on soils, water and air, and indirect effects as a result of the production and supply of inputs to agriculture such as machinery, fuels, fertilizers and pesticides.

Cereals are the major component of livestock concentrate feed. Thirty-two percent of the world's cereal production is consumed by livestock. Yet this cereal is produced on only 20 percent of the total cereal cropland. The total of all cereals, oilseeds and roots and tubers used for livestock feeding is 744 million tons. An additional 252 million tons (about 24 percent) of all concentrates are processing by-products (brans and oilcakes) for which there is little alternative use.

Fig 2.2 Global total utilization of concentrated feed resources ('000 MT per year).
Source: Hendy et al., 1995.

Averages based on 1990 to 1992 data indicate that global cereal production was 1854 million tons, of which 600 million tons were used for livestock feed. Maize is the most important feed grain accounting for 55 percent of total feed grain used, followed by barley and wheat. Soybean is the most important oilmeal, because it supplies more than half the requirements for these high-protein feeds.

The environmental impacts of crop production are site-specific, depending on a whole range of natural and socio-economic conditions and technologies. Therefore generalizations are not possible. However, some specific characteristics of feed concentrate production on the natural resource base are:

- feed is generally produced in more intensive systems in agro-ecological zones of high potential rather than the more erosion-prone marginal areas. In the high potential areas, feed can be produced at low cost, whereas the costs associated with the risks of producing crops under marginal conditions are usually prohibitive. The latter is reflected in the low grain to meat price ratios that prevail in, for example, the Sahel countries;
- feed use most commonly represents the lowest opportunity cost. Typically, feed concentrates are real surpluses, and the feed use acts as a buffer in the overall use pattern.

Fig 2.3 Feed concentrate use by species.
Source: Hendy et al., 1995.

By the mid-1980s concentrate feed accounted for about a quarter of all feeds for livestock; and this proportion was growing at about 0.2 percentage points annually. Concentrates comprise about 40 percent of all feeds in the developed countries and 12 percent in the developing world. Roughly, cereals constitute about 60 percent of total concentrate feed, with most of the remainder provided by brans and oilcakes. Industrial pig and poultry systems are the largest single users accounting each for almost one-third of the total.

Fig 2.4 Feed concentrate use by system.
Source: Hendy et al., 1995.

Growing demand for concentrate feed leads to area expansion and intensification, and thus potentially exerts a wide range of pressures on the environment. Increases in the areas of land used for crop production occur at the expense of other forms of land use, mainly pastures and forests, potentially placing greater pressures on these land resources, with subsequent threats to habitats and biodiversity. However, the extent of this change needs to be put in the context of overall land use. Land with potential for cropping, including marginal areas, represents some 40 percent of total land surface in developing countries but by the year 2010 less than one-third of this land will be cultivated (FAO, 1995). Thus, while changes in land use may be very significant in some countries and locations, they will be reduced at an overall level. The notable exception is the loss of forests where cropland development accounts for up to 60 percent (World Bank, 1992) of the annual deforestation rate of 0.8 percent (FAO, 1994).

The current expansion of cropland is globally very small, 0.1 percent annually, which compares with growth in crop production of 1.9 percent annually. (FAO, 1995). This suggests that the bulk of the increased demand for crops is met by cropland intensification rather than expansion. FAO (1995) estimates that out of the potential cropland of 2,573 million hectares in developing countries only 757 million hectares or little less than 30 percent, is currently in use. The bulk of the currently uncropped land is in the humid and subhumid zones, mostly in Africa and Latin America. It also includes substantial forest areas.

All cultivation results in soil loss and invariably depletes soil nutrients and organic matter. Excessive soil losses result in land degradation and abandonment which currently amount to 6-7 million hectares per year or 0.5 percent of the global cultivated area (El Swaify, 1991) The main causes of these losses are soil erosion and salinization in irrigated areas. Soil erosion causes progressive loss of yields on most soils, requiring expensive correction and supplementation of nutrient. Off-farm impacts of erosion are siltation, reduced water holding and contamination of water supplies.

Box 2.4 The feed-food controversy.
The fact that one-third of the world's grain harvest ends up in the digestive tracts of livestock where the conversion of vegetable protein into animal protein is converted incurring losses of 60 to 90 percent, is disturbing large parts of the public. Often, it is perceived to be irrational and unethical. Among the 996 million tons of concentrates used in 1994 (FAO, 1996), all cereals, roots and tubers, and pulses and some feedstuffs of animal origin (milk powder) can be classified as edible. Edible feedstuffs provide 74 million tons of protein to livestock. In the same year and by contrast, livestock produced 199 million tons of meat, 532 of milk and 45 million tons of eggs, altogether yielding 53 million tons of protein. Leaving aside the differences in nutritional value, the world's livestock sector consumes more protein than it produces. The input/output ratio is 1.41 and continues to grow because livestock production increasingly relies on grains which is only partially offset by gains in efficiency of feed conversion. However, such input-output considerations overlook two important aspects: firstly, ruminants have the capacity to produce protein without being fed protein because of rumen flora activity. This allows for large ruminant populations to produce without being fed high quality feed. Secondly, the quality of different proteins needs to be considered. Proteins of animal origin have a much higher digestibility and nutritive value than most vegetable proteins. However, the question of feed-food competition is somewhat ill-posed. Rather than looking at what potential food goes to livestock one should look at the resource requirements. An example: a highly intensive dairy production system may rely on alfalfa fodder produced under irrigation and with heavy use of external inputs including fossil fuel, fertilizer and pesticides. Alfalfa is not edible but the land on which it is grown, and other resources could be used for food production. Apparently the food feed debate has to do with the value that food has beyond its commodity price - a less tangible religious and cultural dimension. A recent FAO study (1996) shows that the increasing use of feed grains appears not to have had an adverse effect on the provision of cereals for human consumption. In times of food shortages such as in 1974/75, it is in feed use that adjustments are made and food consumption of cereals remained largely unaffected.

Nutrients and organic matter may be supplied by crop residues, composts, animal manure and crop rotations with legumes, but these sources must be supplemented with increasing use of inorganic fertilizer in order to maintain soil fertility. Increased use of inorganic fertilizer carries the risk of nutrient losses to the environment, particularly of nitrates and phosphates leached to groundwater or in run-off to surface water.

Increased crop production entails a decline in biodiversity. The major threat to biodiversity is habitat loss and alteration due to land-use change (World Resources Institute, 1994). Additional impacts are due to effects of crop production practices, such as pesticide use and some tillage practices, on non-target organisms.

Energy expenditure for producing feed concentrates vary widely but can be substantial. In crop agriculture energy consumption is comprised of direct consumption of energy on farms for field crop operations, threshing, transport, irrigation and others and indirect consumption required to produce inputs such as machinery, fertilizers and pesticides. Energy consumption is generally higher per hectare of cropland in developed than in developing countries as input levels are higher to substitute fertilizers for land and mechanisation for human labour. Typically, energy expenditure ranges between three and six GJ per ton of grain. (Compare Stout 1990, Bonny 1993, Pimentel, 1991).

Crops differ in the degree of depletion of soil moisture and water resources, in their relative demands on soil nutrients and in their typical need for applications of pesticides. In general, cereal crops, and in particular maize, have the potential to cause greater environmental damage than other crops. This is due to heavy fertilizer and pesticide use, high water demand and poor ground cover in the early stages of plant development. On the contrary, potential impacts are generally lowest for legume crops, such as soybeans and pulses. Environmental risks due to nitrate and phosphate losses are greatest from maize and wheat while risks of soil nutrient depletion are greatest in cassava and sweet potato.

Gaseous emissions of livestock and waste

Livestock and livestock waste produce gases. Some are local, such as ammonia whereas others, such as carbon dioxide (CO2), methane (CH4), ozone (O3), nitrous oxide (N2O) and other trace gases (together forming greenhouse gases) affect the world's atmosphere, by contributing to "global warming" or global climate change. Livestock's contribution to that effect can be estimated at between 5 and 10 percent. Within this range, there are considerable problems in assigning emissions to single causes.

Carbon dioxide

There are three main sources of livestock-related carbon dioxide emissions. Firstly, all domesticated animals emit carbon dioxide as part of basic metabolic function or respiration, estimated at a total of 2.8 billion MT annually. Secondly, carbon dioxide emissions result from biomass burning, part of which can be attributed to land clearing and bush fires for pasture and enhancing pasture growth. Thirdly, carbon dioxide is released in relation to livestock-related consumption of fossil fuel for heating, manufacturing of machinery and production of feed, etc.

Carbon dioxide is the least aggressive of the greenhouse gases but is emitted in large quantities. Annually, savanna and deforestation fires pump approximately 1.6 billion tons into the atmosphere, between 20 and 25 percent of the total anthropogenic CO2 emission of 7.1 billion tons (Houghton et al., 1995). However, unlike the emission from fossil fuels, the same grasslands and forests recapture part of these emissions. In effect, some of savanna improvement technologies show that improved savannas accumulate 50 tons (or the annual emission of about 15 cars) more per hectare than the traditional unimproved savannas (Fisher et al., 1995).

Leaving aside respiration of domesticated animals, livestock can be associated with about 15 to 20 percent of total carbon dioxide emissions. When the carbon sequestration capacity of natural and improved grassland is considered, the contribution to the net increase in carbon dioxide concentrations in the atmosphere is probably much smaller. There are however, notable differences between the systems. Grazing systems, with little fossil fuel inputs and often considerable sequestration are likely to have a positive carbon balance whereas this balance is likely to turn negative as intensity and commercial inputs increase, such as in industrial systems.

Methane

This gas is much more aggressive (24 times) in causing global climate change than carbon dioxide. It is the product of animal production and manure management, rice cultivation, production and distribution of oil and gas (pipelines), coal mining and landfills. Livestock and manure management contribute about 16 percent of total annual production of 550 million tons (Bolle et al., 1986, see graph). It is produced as a by-product of the feed digestion of mainly ruminants and, on average, about 6 percent of the feed energy is lost in methane (U.S. Environmental Protection Agency, 1995). Methane emission is the direct result of the capacity of ruminants to digest large amounts of fibrous grasses and other feeds which cannot be used for human consumption. Pigs and poultry cannot digest these fibrous feeds and therefore emissions from these animals are relatively low. Methane emissions per unit of product is highest when feed quality and level of production is low, conditions which prevail in the arid and humid tropics and sub-tropics. This offers the opportunity for a win-win situation: improved feeding leading to more efficient and profitable production and to reducing methane emissions.

Twenty percent of methane emanating from animal production comes from manure stored under anaerobic conditions (USEPA, 1995). Here the picture is reversed: high levels of methane emissions from manure management are usually associated with high levels of productivity and intensity, as well as from large production units.

Despite growing livestock populations, global methane emissions from livestock remain static. The reasons for this stagnation are twofold. Firstly, increases in productivity lowers emission levels per animal and per unit of product. Advances in feed resources and nutrition, and breed development are significant contributing factors. Secondly, monogastric production is growing at a much faster pace than ruminant production. About 80 percent of the total growth of the livestock sector is attributed to pigs and poultry which emit comparatively small amounts of methane.

Any reduction in methane production, however, is likely to result increased emission of other gases, notably carbon-dioxide and nitrous oxide, as fossil fuels and fertilizer will be required in the intensification process.

Nitrous oxide

This is the most aggressive greenhouse gas (320 times CO2) contributing to global warming. It is produced in animal manure which contributes about 0.4 million tons N per year, or 7 percent of the total global anthropogenic emissions (Bouwman et al., 1995). Indirectly, livestock are associated with N2O emissions from grasslands and, through their concentrate feed requirements, to emissions from arable land and N-fertilizer use.

Fig 2.5 Sources of methane emission.
Source: Boile et al., 1986.

Currently, the main policy constraint is the lack of appropriate incentives for the many existing technologies to reduce greenhouse emissions. The adoption of biogas technologies which convert methane from manure into energy is often hampered by the price of fossil fuels. In addition, there is still a lack of information on how to value the benefits accruing from reducing the losses in the global commons and on which mechanisms to use for distributing these benefits.

Domestic animal diversity

Increased intensification and industrialization of livestock production requires increasingly uniform genotypes and has caused the extinction of some, and the genetic erosion of other, local livestock breeds. There are currently about 600 breeds at risk of extinction, representing about 20 percent of the total global livestock breeds (Hammond and Leitch, 1995). In addition, it is projected that by the year 2015 the U.S. Holstein population will only have an effective population size of 66 animals, i.e. animals which are unrelated. Pig breeds in China, dairy cattle breeds in India, some of the non-cattle bovine species (yak, gaur, mithun, banteng) and buffalo resources are especially at risk. Development policies favouring exotic breeds (subsidized imports and multiplication of exotic genetic material) and technologies (subsidized machinery, replacing traditional draught breeds) have been primary causes for the erosion of traditional breeds.

Population pressure and income growth create competition for resources in special ecological "niches", which is the main reason for loss of species wealth (Cunningham, 1995). There is a significant statistical relationship between human population density and conversion of habitat into agricultural land. In most cases, however, it is not an over-exploitation of the endangered species but a change in the habitat which undercuts their capacity to survive. The transfer of excessive nutrient to a nutrient poor ecosystem is an example. This is compounded by unfamiliarity with technologies promoting symbiosis of agricultural intensification and biodiversity conservation.

A number of issues in the preservation of biodiversity need to be resolved. While conservation of biodiversity can provide some benefits to farmers, there are a number of benefits, such as the conservation of domestic genetic resources or the preservation of medicinal plants, which will benefit primarily other groups of the global population both now and in the future. This lack of an appropriate valuation of domestic and wild plant and animal genetic resources leads to under-investment. Even where there is no deliberate attempt to distort markets, valuable habitats are converted into agricultural production, including livestock, because other costs, such as loss of biodiversity have not been accounted for.

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