# Industrial livestock systems & the environment

Industrial production1 of pork, poultry and (feedlot) beef and mutton is the fastest growing form of animal production. In 1996, it provided more than half the global pork and poultry meat (broiler) production and 10 percent of the beef and mutton production. This represented 43 percent of total global meat production, up from 37 percent in 1991-93. Moreover, it provided more than two-thirds of the global egg supply. Geographically, the industrialized countries dominate intensive industrial pig and poultry production accounting for 52 percent of the global industrial pork production and 58 percent of the poultry production. Asia contributes 31 percent of the world's pork production (Sere and Steinfeld, 1996 and Figure 4.1).

1 Defined as production systems in which less than 10 percent of the feed is produced within the production unit.

Industrial ruminant production is concentrated in Eastern Europe, the ex-Soviet Union and in the OECD countries (Figure 4.1). Typical examples are large-scale feedlots in the USA and in the former centrally planned economies. Industrial sheep feedlots are found in the Near East, North Africa and the USA.

The industrial production system is open both in physical and economic terms. It depends on outside supply of feed, energy and other inputs. Technology, capital and infrastructure requirements are based on large economies of scale and, because of this, production efficiency is high in terms of output per unit of feed or per man-hour, although less so when measured in terms of energy units. Yet, as the world's main provider of eggs, poultry meat and pork at competitive prices, it meets most of the escalating demands for low cost animal products in rapidly growing urban centres of the developing world.

Figure 4.1 Industrial system livestock production by world region ('1000 tons).

Environmental challenges

Because of its open nature and many interfaces with the natural resource base, the industrial “bio-industry” system signifies for many the epitome of what is wrong with animal production. The industrial scale implies large herd/flock sizes, large volumes of wastes, high animal health risks, and less attention to animal welfare. It has multiple opportunities to dump its waste products without accounting for the environmental costs. There are, however, solutions which could substantially reduce the negative environmental effects, although at a cost. The biggest challenge that the sector faces over the next decade is to identify technologies and establish policies that will internalize the environmental costs.

State

The industrial system acts directly on land, water, air and biodiversity through the emission of animal waste, use of fossil fuels and substitution of animal genetic resources. In addition, it affects the global land base indirectly, through its effect on the arable land needed to satisfy its feed concentrate requirements. Ammonia emissions from manure storage and application lead to localized acid rain and ailing forests, for example in European countries. Also, the industrial system requires the use of uniform animals of similar genetic composition. This contributes to within-breed erosion of domestic animal diversity. The effects of each of the direct agents are described below and the indirect environmental effects of feed concentrate production and the pressure on domestic animal diversity, are described in Chapter 5.

Land, water and air. These are the environmental components mostly affected by the concentration of animals and waste production. Manure is the main agent having effect, mostly during storage and after application on the land. Pigs and poultry excrete some 65 and 70 percent, respectively, of their nitrogen and phosphate intake. Nitrogen, under aerobic conditions, can evaporate in the form of ammonia with toxic, eutrophic and acidifying effects on ecosystems (Wilson and Skeffington, 1994). A greenhouse gas, nitrous oxide (2), is formed as part of the denitrification process with particularly harmful effects on the environment. Nitrates are leached into the groundwater posing human health hazards and run-off and leaching of nitrogen directly lead to eutrophication and bio-diversity loss of surface waters and connected ecosystems. Phosphorus, on the other hand, is rather stable in the soil, but, when P saturation is reached after long term high level application of manure, leaching occurs and this also causes eutrophication (Fig. 4.2).

Figure 4.2 Possible nutrient losses from manure between excretion and crop uptake.
Source: Bos and de Wit, 1996.

Ammonia and other nitrogenous gases result from the digestion of protein, part of which is lost in manure and urine. Growing pigs, for example, excrete 70 percent of the protein in feed while beef cattle excrete 80 to 90 percent and broiler chickens 55 percent (Jongbloed and Lenis, 1992). Ammonia, in high concentrations in the air, can have a direct effect on plant growth, by damaging leaf absorption capacities but its indirect effect on soil chemistry is even more important. Ammonia acidifies the soil, interferes with the absorption of other essential plant elements, particularly in nitrogen-poor ecosystems such as forests. Livestock production is a major source of ammonia emissions in the industrial world. For example, of the 208,000 tons of ammonia emitted in the Netherlands in 1993, 181,000 tons was estimated to come from manure (Heij, 1995). This was about 55 percent of the total acid deposits in the Netherlands, industry and traffic being other important contributors. In many developing countries, industrial pollution, especially from high sulphuric acid coal burning is the more important source of acid rains. Ammonia also constitutes a health threat for farm workers.

The various forms of nitrogen losses lead to much reduced levels available for crop nutrition. Plant uptake and use depend on a series of other factors such as species, climatic and soil conditions. According to Bos and de Wit (1996), 20, 50 and 44 percent of the nitrogen excreted by pigs, broilers and laying hens respectively are lost to the atmosphere as NH3, as shown in Table 4.1. Because of its different chemical properties, phosphorus losses are insignificant because phosphorus mainly remains in the soil.

Table 4.1 Annual global nitrogen production in manure and losses of industrial monogastric systems (in million tons).
Management system | Source of loss | Broilers | Pigs
In stable | excreted | 3.4 | 3.5
various losses | 1.2 | 1.6
for land application | 2.2 | 1.9
On land | NH3 losses | 0.5 | 1.1
available for crop nutrition | 1.7 | 0.8
Source: Estimated from data from Bos and de Wit, 1996.

The amount of N, P, K and other nutrients available to the crop within the soil determine the fertilizer value of manure. Further significant losses may occur depending on the type of stable and manure management system (Safely et al., 1992) and thus define the direct environmental impact (Table 4.2).

Substantial nitrogen and phosphorus losses also occur when manure is applied on the land. Box 3.8 gives an overview of key factors affecting the environmental effects of manure spreading. The spreading of manure directly on the land can lead to nitrogen leaching into the water as nitrates and contamination of surface waters. This in turn leads to high algae growth, eutrophication and hence damages aquatic eco-systems. Not all soils are equally susceptible to nutrient loading and (ground) water contamination. Sandy soils with low cation exchange capacity, and therefore poor retention characteristics and high run-off, are particularly at risk.

Table 4.2 The relative importance of different manure management systems (percentages for each animal type)
Animals | Lagoons | Liquid systems | Solid storage | Anaerobic digester | Burned for fuel | Deep pit stacks and litter | Directly discharged
Pigs | 10 | 71 | 10 | 1.5 | 1.5 | 5 | 1
Broilers |  |  |  |  |  | 100 |
Laying hens | 1 | 77 | <1 |  | 1 | 20 |
Beef |  | 6 | 88 |  |  | 6 |
Source: Compiled by Bos and de Wit, 1996.

Because of feed's high energy content and, for example, the direct use of fossil energy to heat stables, significant amounts of CO2 are emitted. Anaerobic decomposition of manure also releases large amounts of methane into the atmosphere when it is stored in liquid form (Chapter 5).

Heavy metals. Copper and zinc, which are essential minerals for livestock diet, are deliberately added to concentrate feed whereas other heavy metals, in particular cadmium, are introduced involuntarily via feed phosphates. Only 5 to 15 percent of metal additives are absorbed by animals, the rest is excreted. Soils, on which pig and poultry manure are continuously applied at high rates, accumulate heavy metals, jeopardizing the good functioning of soil, contaminating crops and posing human health risks (Conway and Pretty, 1991).

Fossil fuels. The industrial system is a poor converter of fossil energy. Fossil energy is a major input of intensive livestock production systems, mainly indirectly for the production of feed. For example, Table 4.3 shows that feed accounts for 72 to 74 percent of the total energy input, except for veal production where it is almost 90 percent. Similar observations can be made for industrial pig and poultry production (Table 4.4).

Table 4.3 Energy input of some types of industrial meat production systems (in Mega Joule (MJ) per kg of liveweight).
Component | Beef | Veal | Mutton
Energy input feed1) | 11.5 | 41.7 | 14.0
Energy input animals2) | 1.3 | 1.5 | 0.8
Energy input fattening (buildings, equipment, fuel and other) | 2.7 | 3.6 | 4.5
Total energy input | 15.5 | 46.8 | 19.3
1) includes fossil energy requirements for production, transport and processing of feed 2) fossil energy for the production of the animals
Source: Brand and Melman, 1993.

Energy output for livestock products comprises food and non-food items. Southwell and Rothwell (1977) calculated output/input ratios of 0.38, 0.11 and 0.32 for pork, poultry meat and eggs respectively, while for milk it was 0.5. These calculations take into consideration fossil energy input only.

A large portion of non-food energy output is in the form of manure and the potential for recovery of this energy has greatly increased in recent years. Techniques for methane recovery are described in Chapter 5. The heavy concentration of animals in certain regions, particularly in the pig and poultry systems, has given rise to the development of large scale processing of manure for use elsewhere. Manure processing and transport further increases fossil fuel consumption, particularly if drying is involved. This extra energy expenditure may offset the energy savings made by concentrating livestock production.

Biodiversity. The industrial system has a threefold effect on species wealth through:

- its demand for concentrate feed, which changes land use and intensifies cropping. The production of feed grains, in particular, adds additional stress on biodiversity through habitat loss and damages in ecosystem functioning;
- waste production and its effects on terrestrial and aquatic ecosystems. These effects are often geographically confined to areas of high livestock densities. Eutrophication and destruction of habitats is a common phenomena in parts of north-eastern Europe and the USA as well as in the densely populated areas of the developing world, in particular Asia and to a lesser extent, Latin America. Ammonia emissions lead to acidification of particularly fragile habitats and so causes losses in biodiversity; and
- the requirement for extremely uniform animals of similar genetic composition. This contributes to within-breed erosion of domestic animal diversity, and is discussed in detail in Chapter 5.

Table 4.4 Energy input for pigs and poultry systems (in MJ per kg of liveweight).
Component | Pork | Poultry meat | Eggs
Canada | Netherlands | Canada | Netherlands | Canada | Netherlands
Housing
- fuel, electricity | 3.0 | 3.0 | 8.2 | 3.5 | 5.4 | 1.2
- building equipment | 0.4 |  | 1.0 |  | 0.5 |
Total Housing | 3.4 | 3.0 | 9.2 | 3.5 | 5.9 | 1.2
Feed
- transport |  | 3.7 |  | 2.4 |  | 3.6
- production, processing |  | 12.2 |  | 12.2 |  | 9.3
Total feed | 20.5 | 15.9 | 13.6 | 14.6 | 18.9 | 14.1
Total energy input | 23.9 | 18.9 | 22.9 | 18.1 | 24.8 | 14.1
Sources: Southwell and Rothwell, 1977, Leijen et al., 1993 and Brand and Melman, 1993.

Environmental benefits of industrial production systems. First, the rapid development of “modern” industrial pig and poultry systems helps to reduce total feed requirements of the global livestock sector to meet a given demand. It may therefore alleviate pressures for deforestation and degradation of rangelands, such as is happening in parts of Latin America and Asia, thus saving land and preserving biodiversity. Second, the feed-saving technologies developed for this system can be effective at any scale and therefore can be successfully transferred to mixed farming systems. The same holds true for waste prevention and treatment technologies which have been developed following regulations applied mainly to the industrial system. Therefore, the resource-saving and waste management technologies generated by the industrial systems bring benefits to the sector as a whole.

Driving forces

Population growth, rising income and urbanization are the fundamental driving forces determining growth of industrial livestock production. Globally, industrial animal production is the fastest growing sector, with over 4 and 5 percent growth per year in pork and broiler production, respectively. Annual growth for eggs is 3.8 percent and for mutton and beef 2.5 percent. Driven by rising incomes and rapid urbanization (which in itself causes an increase in meat consumption), Asia experienced over the last decade a staggering growth of 9 percent per year in industrial pig and poultry production, and this trend can be expected to accelerate. Sub-Saharan Africa shows good growth in all monogastric products, while Latin America continues to exhibit significant growth in poultry products. In Western Europe and the USA, growth is levelling off, while in the former Soviet Union, after the transition, all intensive meat and egg production is shrinking.

Industrial animal production has become concentrated in certain areas because of a number of factors which usually interact:

- Transport costs and market opportunities are the main determinants. First, the industrial system, especially for pigs and poultry, is characterised by a significant, and often exclusive, use of feeds of high energy content (mainly cereals, oilseeds and their by-products). This high energy density allows movement of feeds over longer distances at substantially lower costs than perishable animal products, even though the quantities are larger. For example, sea transport costs of grains is one-tenth per unit weight that of frozen meat Cunningham (1992). Thus, with an average feed conversion of 3:1 for pigs and 2:1 for poultry it is less costly to transport feed than meat. In addition, over short to medium distances, live animal transport costs are similar to those of grains. These relative costs encourage production, slaughter and meat processing facilities to be located near urban centres. The large number of industrial units being established around Beijing, Shanghai, Mumbai and Calcutta demonstrate this incentive for close proximity to the consumer. Second, ruminants require fibrous feeds such as silage, hay or fresh chopped forages, in addition to concentrate feed, to maintain the rumen functions. This requirement increases the transport costs for feed significantly and explains why industrial ruminant production is generally more connected to the landbase (and less to the consumer market) than pigs or poultry. In addition, feed conversion of concentrate feed per kg of beef or mutton is substantially poorer than with pigs and poultry. Intensive beef production is therefore only competitive where consumers can afford to pay a substantial premium for quality beef over chicken or pork. Third, in net grain importing developed countries, with abundant road and cooling infrastructure, large-scale industrial operations are located close to ports, such as pig operations in the Netherlands and northern Germany.

Box 4.1 Feed imports and nutrient surpluses.
The Netherlands, France (Brittany) and Denmark depend, respectively, on 85, 40 and 20 percent on feed imports for their intensive pig and poultry industry. As a result, large quantities of manure have to be transported over long distances (up to 100 km in the Netherlands) to “manure deficit” areas. In Brittany, the distance over which manure is transported needs to cover, on average only 15 km, whereas in Denmark almost all manure can be applied in the immediate surrounding area.
Source: Estimated from Bos and de Wit, 1996.

- Agrarian structure has favoured high livestock densities and the evolution of industrial-type systems where shrinking farm size forced farmers to engage in value-adding activities without significant land requirements, such as in some southern parts of Germany and the Netherlands, or to abandon agriculture altogether. This move has been favoured by price subsidies with the main objective of supporting rural populations; and
- Different policy settings within a country or free-market zone through, for example, tax advantages, low energy costs or low environmental standards, may lead to concentration of the industrial system. An example is where intensive poultry, and more recently also pig production, moved from the corn belt of the USA to the southern States, and, in the EU, to Italy and Spain.

Policies. In the past, industrial and intensive mixed farming systems have benefited from policy distortions and the absence of regulations or their enforcement and, in many cases, this vacuum has given this system a competitive edge over land-based systems. Furthermore, some policies have misdirected resource use and encouraged the development of technologies which are inefficient outside the distorted context. For example:

- In the EU, high domestic prices for beef, pork and milk, together with cheap imports of cereal-substitutes, such as cassava (Box 4.2), have benefited industrial production. In addition, parts of the industrial ruminant system, for example, veal production, have greatly benefited from the subsidy policy on milk replacers. This policy originated from the surplus production of milk caused by milk quotas in excess of market requirements although these have also been reduced;

Box 4.2 The international transfer of nutrients: the cassava story.
Differential import tariffs for cereals and cereal substitutes such as cassava and sweet potato meal, and improved feed formulation techniques strongly promoted the import of those cereal substitutes from the Far East, leading in the early '90s to an import of 7 million tons (15 percent of the EU's total consumption of energy feeds, mostly in the Netherlands). This implies an annual import of about 40,000 tons of nitrogen and 7,000 tons of phosphorus, or about 15 kg of N per hectare per year agricultural land there, which, as it is not evenly distributed, constitutes a considerable environmental burden.

- In WANA, small ruminant feedlots were (and still are) heavily dependent on subsidized feed, and this has encouraged inefficient feed use;
- In the former centrally planned economies, the feedlot system was based on heavily subsidized feed grain and on subsidized fuel and transport; and
- Many developing countries not only have direct subsidies on feed but also on energy. As energy is a major direct and indirect cost item in industrial production systems, economy wide policies often tend to favour industrial production over grazing systems and mixed farming.

Finally, in practically no country in the world, is the industrial system charged with the full environmental costs of production. It appears that societies prefer the cheap supply of animal products over the functions of concerned ecosystems. Self-sufficiency in animal products and supply of high-value food commodities to urban populations seem to be overriding policy objectives, particularly in developing countries.

Response: Technology and policy options

In the developed world, stagnating demand and increasing human health concerns have, to some extent, alleviated the pressure. For example, growth of industrial beef feedlots in North America, is still only driven by population growth, because per capita consumption of beef has remained constant. The importance of feedlots in the European Community is likely to decline as production becomes more extensive in response to policies that reduce support to agriculture and promote environmentally friendlier production systems. With the shift to a market economy in Eastern Europe and the former Soviet Union, the importance of industrial ruminant production is declining and ruminant production is moving back to the land base and to smaller scales of operation.

In addition, and more importantly, the pollution of land, water and air has raised acute awareness in the developed world of the environmental problems associated with industrial production systems. This has, in many cases, triggered the establishment of policies and regulatory measures, removing many of the favouring factors, and inducing a series of technologies that are increasingly applied, wherever regulations are enforced. They are detailed below.

Box 4.3 Point versus non-point source pollution.
Point source pollution originates from a specific location and it is usually possible to determine how much of the pollution is entering the environment. Discharge of manure into surface waters, for example, is point source pollution. Non-point source pollution results from seepage of surface discharges, precipitation or atmospheric deposition. It spans a wide area of land, often depending on weather conditions, making both the occurrence and extent of pollution difficult to predict. Environmental damage through excess manure application to land is non-point source pollution.

Policies and regulations. Regulatory instruments are imposed to control the distribution and concentration of livestock production and introduce technical control systems. Some of these regulations are relatively easy to enforce whereas others, for example the maximum permitted amount of manure per unit area, are more difficult. The regulatory approach is most efficient in situations of point source pollution (Box 4.3) and where there are strong enforcement institutions. In countries with weak institutions, the enforcement of regulations at reasonable social cost remains a major challenge and limits the validity of this approach. Compliance with regulations affects cost of production and may therefore influence regional distribution. Specific examples of regulations are given in Table 3.4. They include the limits on the number of animals in the EU, and most of the member states, taxes on surplus animals as in Belgium (Manale, 1991), taxes on surplus P (most EU countries), a ban on direct discharge of manure into surface waters (USA, Malaysia), and the establishment of nutrient management plans (Indonesia, the USA and a number of European countries). Guidelines on manure storage and application methods, timing, crops and quantities are available in practically all countries with high animal densities.

Box 4.4 Livestock waste in Singapore.
Between 1967 and 1987, the densely populated island state of Singapore went through a series of policy changes and technology adaptation and developments. Initially food security policies and consumer preference for fresh meat resulted in an upgrading of technologies, including least cost feed formulations, improved animal husbandry and veterinary health. In the 1970s, Singapore achieved self-sufficiency in eggs, poultry meat and pork. Starting in the late '70s Singapore started to establish a network of waste discharge measures including a 95 percent reduction of Biological Oxygen Demand, BOD (see Chapter 5) and a sludge of at least 20 percent total solids content (Taiganides, 1992). Technologies for waste disposal were mainly imported from western developed countries and adapted to the specific conditions. In spite of having to incorporate a large part of the environmental costs in their prices, Singapore producers remained competitive vis-á-vis live animal imports. In 1984, environmental standards were raised, particularly with regard to odour control. In the same year, Singapore abandoned the national objective of self-sufficiency in monogastric products and pig farming was phased out in 1987.

Zoning can regulate regional distribution. Zoning is, and will remain, an important policy for controlling animal manure storage and processing, not only for environmental reasons but also for concerns of human health and rational regional development. Zoning has been important both in environmental and in regional development policies, as well as in successfully moving industrial production units away from urban centres in OECD countries. An important prerequisite for successful zoning is good infrastructure because animal products will have to be transported over larger distances. Marketing and processing infrastructure must therefore be taken into account when defining zones in order to make the best use of investment. The creation of confined “industrial parks”, with prescribed and sometimes shared facilities for waste collection and treatment, offers opportunities to fully charge industrial production systems with environmental costs while still maintaining advantages of market access and economies of scale. Governments have frequently established guidelines for the siting of production units, particularly to protect urban settlements from obnoxious smells. Zoning, when done within a comprehensive area development plan, also allows for common waste collection and treatment facilities to be shared by a number of producers. The ultimate zoning strategy has been introduced by Singapore, which completely prohibits animal production (Box 4.4).

A trend to rational zoning is not only fostered through environmental concerns but also by changes in overall policies, often triggered by the removal of government interventions and trade liberalization. In the Near East, for example, industrial small ruminant systems have been kept viable through subsidies on grains and are increasingly under pressure because of the financial requirements to maintain these subsidies.

Box 4.5 The effects of internalizing environment costs on production costs and income.
No systematic evaluation exists and data are scarce. Costs are very site-specific and rarely are full environmental costs actually covered. However, regulations for intensive production systems in some countries are so strict that practically all environmental costs, at least for waste, are absorbed by the producer. Here are some examples: In Malaysia, for cultural reasons swine production is kept out of sight and no pig manure can be applied to land. In certain prescribed areas, industrial pig producers have to reduce BOD to less than 50 mg/l (95 percent reduction), through screening and aerobic treatment. For a 500 animal pig unit, investment costs are around 10 000 Ringgit Malaysia (RM) and operating costs are 24 RM per production place (Hassan, pers. com.). This implies an incremental production cost of 0.23 RM (approx. 9 US cents) per kilogram of liveweight produced, equivalent to a cost increase of around 6 percent. In Singapore, in 1986, the large-scale Ponggol Pigwaste plant turned wastewater into recycled water (7 mg/l BOD5), essentially removing all waste-related environmental effects. Total average annual costs were calculated at US$ 14.39 (Taiganides, 1992) per porker marketed or between 8 and 9 percent of total production costs. Australian beef feedlot regulations are the strictest in the world and contribute to construction costs of new feedlots being much higher than in the United States. Most feedlots are in the vicinity of grain producing areas. The regulatory frameworks differ between the States and costs of compliance with environmental regulations have been given at A$ 27 per head for feedlots in Queensland and A$ 41 for New South Wales (Ridley et al., 1994) or approximately 4 and 6 percent respectively of total production costs. Investment costs related to compliance with environmental regulations are 6 percent of total investment costs. While it appears that overall impact on production costs, even in extreme cases, do not exceed 10 percent incremental costs, investment requirements and effect on income can be prohibitive if such measures are applied unilaterally. Furthermore, unit costs for establishing and operating waste treatment facilities decrease with increasing size, so small producers are disadvantaged. However, the latter often face less severe regulations, such as dairies in the USA, or are exempted altogether.

The most efficient and direct financial instrument would be to internalize all environmental costs into the consumer price. This should certainly be the policy over the medium term. However, implementation of such policies is not easy. First, there is a lack of accurate economic evaluation of these costs, for example for biodiversity and some gaseous emissions and some indirect costs (soil erosion because of feed production, for example). Initial calculations point to an increase of 10-15 percent in cost price (Box 4.5). Second, unequal application of the inclusion of environmental costs in the product price puts some producers at a comparative disadvantage. A more global approach will therefore be required.

Current financial instruments therefore focus on reducing the emission of nitrogen and phosphates and other potential pollutants, particularly in susceptible and already burdened areas. The levies and taxes currently imposed on the intensive mixed and industrial systems in practically all developed countries fall into this category. This includes many of the measures listed above, such as levies on waste discharge, taxes on excess animals or phosphate-loads. Others are:

- removal of subsidies, or imposition of taxes on imported concentrates, to increase the cost of feed concentrate-intensive production and to favour land-based systems over the industrial system. This is the main cause that large-scale feedlots can no longer compete in the contracting market of the former centrally planned economies. Here, the general trend points to a more land-based livestock production, removing a large part of the waste problem in the medium term. In a more indirect way, removal of subsidies or taxes on fossil fuel may have a similar effect by raising the cost of feed. Government income from such sources could be used to alleviate environmental problems;
- removal of import restrictions on materials and equipment that improve feed efficiency, such as amino-acids to improve protein, enzymes to improve phosphate digestion and feeding equipment that restricts intake. These technologies lead, indirectly, to lower waste loads through better feed conversion;
- subsidies for investment or running costs to improve the adoption of emission control technologies. For example, subsidies for constructing manure storage facilities are given in many EU countries. In the USA, cost-sharing and state revolving funds have been established for manure storage sheds and dead bird composters; and
- a system of tradable manure emission quota to limit waste production and still create incentives for efficient resource use. Marketable permits and pollution trading would be based on the establishment of payment per unit of pollution or the use of pollution reduction credits.

Technologies. As can be expected according to the theory of induced technology (Chapter 1), these measures have led to the introduction of a wide range of new techniques. Because of the commercial and demand-driven nature of the industrial system, development and transfer of technologies are usually not a problem, although their impact can be expected to level off as high levels of technology are reached.

A whole range of technologies exists that could alleviate the environmental burden created by this system. The effectiveness of these technologies with regard to manure disposal can be measured with parameters as described in Boxes 4.6 & 3.8. These technologies seek improvement in two areas:

Reduction of nitrogen and phosphate excretion by improving feed utilization can be achieved through:

- introduction of multi-phase feeding in order to match feed composition to the needs of the individual animal classes. By better adjusting the nutrient supply to the needs of animals, less waste is produced and therefore less nitrogen and phosphates are released in waste and into the environment;
- improving the accuracy of determining nitrogen and phosphate requirements, followed by better balancing of feeds with these essential nutrients. In this respect, important gains have already been obtained in better balancing pig and poultry rations with essential amino-acids, the building blocks of feed proteins. For example, a combination of better balanced feed improved digestibility and the inclusion of synthetic amino acids, allows for a substantial reduction of the protein content in feed and, hence, a reduction of nitrogen excretion by 20 to 40 percent (Van der Zijpp, 1992). Concentrate conversion rates range between 2.5 to 3 kg feed dry matter/kg liveweight gain in pigs, 2.0 to 2.5 kg feed /kg of liveweight gain in broilers, and even less for eggs. They have been reduced by at least 30-50 percent since the '60s; for example, the average feed conversion of pigs in the Netherlands in 1957 was 3.5 kg feed per kg liveweight gain (Grashuis, 1958). Through selection and better feed formulation, there is considerable potential for further improvement (Chapter 5). For ruminants, key production efficiency parameters are daily weight gains and feed conversion, which reflect the profitability of the use of capital for feed, lean animals and investments. Cattle weight gains are usually in the range of 1 to 1.5 kg/day and feed conversion rates are of about 8 to 10 kg of grains per kg of weight gain during their period in the feedlot. A more detailed discussion of concentrate to animal conversion is given in Chapter 5. Other options include the use of growth hormones (somatropine) or other stimulants (clenbuterol), frequently used in the USA, but banned in most of Europe;

Box 4.6 Indicators for manure management.
nutrient balance: manure P/crop P. distribution of manure over available land. exposure to air and contact with soil. time lapse between application and planting. time lapse between application and working-in. use of water with liquid manure. nitrogen losses. organic matter losses.

- increasing diet digestibility. Spectacular improvements have been obtained with the addition of an enzyme (phytase) for catalysing the digesting of phosphates in feed. The same enzyme might also increase the availability of zinc in feed, reducing the need for feed additives; and
- promoting feeding systems which reduce intake and stop the buffet-style, ad libitum feeding which was popular in the 1980s.

Reduction of the emission from manure storage and during application. Possible technologies are:

- a reduction of nutrient losses from manure in stables and during storage through improved collection and storage techniques. In animal buildings, manure is stored either under a solid floor, under a slatted floor, or within a housing system with litter. A large part of ammonia emissions comes from the manure surface in storage, either under the slatted floor or in open tanks. The main focus has to be on reducing nitrogen losses, most of which are in the form of ammonia from the manure surface. Possibilities are:

Solid storage systems, which collect the faeces only for storage in bulk (often for extended periods), and have low gaseous emissions;

Liquid or slurry systems where animals are kept on slatted floors and the manure and urine are collected and stored in large tanks. This system is particularly common in pig production, and part of the energy may be recovered through the use of anaerobic digesters;

Lagoon systems consist of flushing systems using large amounts water. Nitrogen losses and methane emissions are high;

Covered tanks and manure kept under solid floors in stables. Minimal amounts of ammonia are emitted when manure is stored under solid floors. Reductions in emissions of 80 to 90 percent can be achieved by covering storage tanks (Voorburg, 1994); and

Reducing odour and ammonia after emission from the source. In addition to natural or forced ventilation systems the air can be cleaned through bio-filters or bio-washers that absorb odours and ammonia from polluted air. This is done by oxidizing ammonia into NO2 and NO3. Up to half of the ammonia can be eliminated through such air washing systems. However they are costly in investment and operation. (Chiumenti et al., 1994).

Box 4.7 Joint biogas plants in Denmark.
For the protection of water resources, Denmark has established regulations that allow manure to be applied only during the growing season. Consequently, the manure has to be stored for up to nine months, creating immense storage problems and costs. This induced an initiative in 1988 by which a number of farmers are served by Joint Biogas Plants which are large common storage facilities. This overcomes the problem of economies of scale which individual farmers would be unable to overcome. In 1994 nine plants delivered more than 2 million m3 monthly to public utilities. (Johansen, 1995)

- methods that efficiently re-use energy and nutrients in manure in cases where manure is not used directly for agriculture. Biogas plants of all sizes and different levels of sophistication exist. They not only recover the energy contained in manure but also eliminate most of the animal and human health problems associated with micro-biological contamination of waste by micro-organisms. Other methods of controlling the waste load are purifying and drying the manure;
- reducing nutrient losses during and after application of manure on soils (Chapter 3). Injection or sward application of manure into the subsoil and appropriate timing significantly reduces nitrogen losses as shown by the Netherlands' experience since 1995. Nitrification inhibitors can be added to slurry to decrease leaching from the soil under wet conditions;
- large-scale manure processing is possible where intensive production is concentrated in certain zones but that is often not viable economically. The efficient use of manure for feed and energy production requires high capital investment which often cannot be borne by individual farmers (Box 4.7); and
- recycling manure by feeding it back to livestock, including fish (Muller, 1980) is practised only on a limited scale. In addition to widespread reluctance to use manure as feed, mainly originating from fear of health hazards, most types of manure have a low nutritive value with the exception of poultry manure which is of reasonable quality, i.e. 55-60 percent Total Digestible Nutrients (TDN) and 20-30 percent Crude Protein (CP). Consequently, in intensive production systems with large amounts of collectable manure, cheaper feeds are also available, while in production systems where utilization of low quality feeds is common, high collection and opportunity costs (manure as fertilizer or fuel) prohibit the use of manure as feed. A recent overview of the possibilities is given by Sanchéz (1995).

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