MINIMISING ENVIRONMENTAL IMPACTS OF LIVESTOCK PRODUCTION
THROUGH GOOD MANURE AND NUTRIENT MANAGEMENT
Harald MENZI, Swiss College of Agriculture (SCA), CH-3052 Zollikofen, Switzerland
The following text gives a brief overview on possible environmental impacts of intensive
livestock production (especially pigs) and the principles of good manure and nutrient
management. Critical aspects are highlighted for discussion in a number of hypothesis and
important information is formulated as key-questions. The key-questions mostly focus on actual
situation and the needs assessed in the framework of the four projects currently implemented by
LEAD in Thailand, China, Vietnam and Mexico (see the LEAD Virtual Centre for more
information on those projects)
1. WHY ARE ENVIRONMENTAL IMPACTS AN IMPORTANT TOPIC FOR
LIVESTOCK PRODUCTION?
1.1 ENVIRONMENTAL RISKS OF INTENSIVE LIVESTOCK PRODUCTION
Livestock excretes 70 to over 90% of the nitrogen (N), minerals (phosphorous P; potassium K,
magnesium Mg, etc.) and heavy metals taken up in the feed. Livestock excreta, which will
furthermore be called manure (solid and liquid manure), therefore contain a considerable amount
of these substances. If these get into the water or accumulate in the soil, they can be a serious
threat to the environment. The major environmental threats of intensive livestock production are:
* EUTROPHICATION of surface water (deteriorating water quality, algae growth, damage to
fish etc.) due to input of organic substance and nutrients if excreta or waste water from livestock
production get into streams through discharged, run- off or overflow of lagoons. Surface water
pollution threatens aquatic ecosystems and the quality of drinking water taken from streams.
* LEACHING of nitrate to the ground water from manure storage facilities for liquid manure or
from fields on which high doses of manure have been applied. Nitrate leaching is especially a
threat for drinking water quality.
* ACCUMULATION of nutrients and heavy metals in the soil if high doses of manure are
applied. This can threaten soil fertility.
* Spreading of DISEASES AND PATHOGENS harmful to human and animal health.
* ODOUR, which can be a nuisance in populated areas.
* VOLATILISATION OF AMMONIA to the air e.g. from animal houses, open manure storage
and manure spreading. Ammonia causes N-deposition and eutrophication of sensible ecosystems
* METHANE IS PRODUCED under anaerobic conditions in manure storage. Methane causes
global warming.
Agricultural production systems are only sustainable if these environmental impacts are kept to a
minimum. This is only possible with good manure management which prevents any manure
discharge or run-off into watercourses and excessive manure applications to land.
****************************************************************************
HYPOTHESIS 1: To be sustainable, livestock production must be environmentally sound. This
means that water and soil pollution must be kept to a minimum.
HYPOTHESIS 2: Any discharge of manure or waste water to water courses must be prevented.
KEY-QUESTION 1: Are the above mentioned risks experienced as real problems and under
which circumstances ? What indicators could be used to assess the environmental impact of
livestock production?
****************************************************************************
1.2 PRINCIPLES OF GOOD MANURE AND NUTRIENT MANAGEMENT
Good manure and nutrient management as defined in the AWI projects, according to local
technical and economic conditions means that:
* No manure (solid or liquid) is discharged to water courses.
* Manure is recycled in agriculture as fertiliser or feed. In fact, under the observed economic
conditions, the biological treatment of manure (aerobic and anaerobic) to decrease it's nutrient
content so it could match discharge standards is not affordable. On the contrary, recycling allows
for valuing those nutrients.
* Manure is stored in such a way that leaching and run-off or overflow losses are prevented.
* Manure is stored long enough or treated in such a way that pathogens are eliminated.
* Manure is dosed according to the N and P2O5 demand of the crops. For N, only about 30-70%
(depending on manure type) of the total N content (Kjeldahl-N) can be counted as available for
crops.
* Manure and mineral fertiliser are only used in such doses that the total nutrient input does not
surpass the crop nutrient demand (nutrient balance in equilibrium).
* Heavy metal inputs in animal feed are restricted in such a way that the heavy metal dose in
manure does not surpass the uptake in crops.
Biodigestors are successfully used in our AWI project countries (mainly China and Vietnam) to
produce methane at farm level (mainly for private use) and, in fewer cases at a larger scale
(neighbourhoods, small villages). It can improve the odour and pathogen situation, but has little
or no effect on the manure's nutrient load. Contents in macro and micro- nutrients, as well as
heavy metals are unchanged after the biodigestion. Therefore, we believe it is an interesting
segment of the manure processing chain that can produce substantial added value, but we do not
include it in this introduction to manure and nutrient management.
It is much easier to handle solid manure in an environmentally friendly way than liquid manure,
because it is more concentrated and can be transported more efficiently. In many developing
countries there is a market for solid manure, while liquid manure is usually not utilised. Liquid
manure (including "waste water") is therefore the main environmental threat of intensive
livestock production. Pig production is in most cases a much bigger threat than poultry
production which mostly produces solid manure. In most countries, activities to reduce
environmental impacts of manure management should therefore in first priority focus on liquid
manure.
The principles of good manure and nutrient management can only be met if there is enough land
to spread the manure without risk of nutrient balance surplus or if the manure can be used as feed
or exported from agriculture. For 100 fattening pig places, a crop area of 10-20 ha is needed.
Consequently, large pig farms need very large surfaces to utilise their manure and the "carrying
capacity" for livestock of a region is limited. Herbivores usually pose less problems for the
nutrient balance than pig and poultry because the surface needed to produce their forage
automatically limits the possible animal density.
Even if manure is used on crops, it often poses a serious threat to the environment. This is for
example the case if the total amount of nutrients used in manure and mineral fertiliser is
considerably higher than the crop nutrient demand, if manure is utilised in such a way that
emissions to water bodies are high or if the soil is harmed by the application machinery or by
high heavy metal doses.
****************************************************************************
HYPOTHESIS 3: All manure must be recycled in agriculture as fertiliser or feed.
HYPOTHESIS 4: The amount of nutrients in manure and mineral fertiliser should not surpass
the crop nutrient demand (nutrient balance in equilibrium).
HYPOTHESIS 5: Heavy metal use in feed should be restricted to prevent heavy metal
accumulation in soils on which manure is used.
HYPOTHESIS 6: In most countries activities to reduce environmental impacts of manure
management should in first priority focus on liquid manure.
KEY-QUESTION 2: What are experiences with existing or new manure management practices,
under which conditions are they successful and where have they failed?
****************************************************************************
1.3 MAJOR RESTRICTIONS FOR MANURE USE AS FERTILISER ON CROPS
Manure management, especially the dose and time of application must not only take into account
the minimisation of negative effects to the environment but also the prevention of negative
effects on the yield and the quality of the crops. It is well known that excessive manure doses can
negatively influence crop quality (e.g. protein content, taste) and even crop yield (e.g. through
lodging). Negative effects, especially on yield, are also possible if the nutrients applied in the
manure are not sufficient or not available to the crop at the right time.
As the utilisation of solid manure usually poses little problem, restrictions for manure use as
fertiliser on crops must in first priority be analysed for liquid manure. According to the
experience in the different AWI projects, the major factors limiting or preventing the use of
liquid manure as fertiliser are:
* There is no tradition and therefore no experience with using liquid manure on crops.
* The technology for manure handling (storage, transport, spreading) are not known by farmers
and to great extent have not yet been developed for the conditions in developing countries.
* Farmers have seen or heard of cases where excessive manure discharge to land caused serious
problems with crops.
* Farmers fear that liquid manure could have a negative effect on crop quality and yield. They
have no examples to contradict this fear.
* Farmers have no recommendations and tools for the optimal use of liquid manure.
* The handling of liquid manure is too complicated, work-intensive and dirty.
* It is cheaper to buy mineral fertiliser than to use the corresponding amount of nutrients in the
form of liquid manure with its high costs for storage, transport and spreading.
* Crop farmers do not want to support rich large livestock farmers.
Apart from policy guidelines, efforts to improve the manure management must focus on
contradicting or elimination these restrictions. In most countries it will probably be more difficult
to convince crop farmers than livestock farmers about the benefits of using liquid manure as
fertiliser.
****************************************************************************
HYPOTHESIS 7: Costs and lacking experience, recommendations and demonstrations of good
manure management are the main factors hindering crop farmers to use liquid manure as
fertiliser.
HYPOTHESIS 8: At least for strongly diluted liquid manure it will be very difficult to be
competitive with mineral fertiliser in terms of costs.
HYPOTHESIS 9: In most countries it will probably be more difficult to convince crop farmers
than livestock farmers about the benefits of using liquid manure as fertiliser.
KEY-QUESTION 3: Under what conditions will crop farmers have more interest in using
manure ?
KEY-QUESTION 4: What policy influencing manure management is in practice in the various
countries. What experience is available on its implementation?
****************************************************************************
2. IMPLICATIONS OF GOOD MANURE AND NUTRIENT MANAGEMENT FOR
LIVESTOCK FARMS AND CROP FARMS USING MANURE
2.1 AWARENESS OF THE POTENTIAL PROBLEM
The most important prerequisites for a manure and nutrient management respecting the
environment are the awareness of all the stakeholders of he potential risks and their willingness
to cope with the problem. Awareness building will therefore have to be the first step in any
program aiming at an improved manure management. Under most circumstances the awareness
building process has to be well established before specific policy measures have any chance of
success.
Once the awareness of the problem and the willingness to cope with it has been established,
farmers will demand specific and reliable recommendations for measures that are applicable
(technically and economically) and effective on their farms.
****************************************************************************
HYPOTHESIS 10: The awareness about the problem of environmental impacts of livestock
production has to be well established before specific policy measures have any chance of
success.
****************************************************************************
2.2 MANURE PRODUCTION AND MANURE QUALITY
One of the most important handicaps of manure compared to mineral fertiliser is its variable and
mostly quite unknown quantity and quality. To furnish such information is therefore an
important challenge for extension services. Basically such information can be provided in the
form of guide values that are simple to use or as a model calculating manure production and
composition on the basis of livestock management, feeding, housing and storage system etc.
An important message to farmers is that minimising the amount of nutrients and heavy metals in
the livestock production cycle is an essential step to reduce environmental problems. As this
requires them to limit the protein, mineral and heavy metal content of the feed to the level
essential for the animal and to achieve a good feed conversion efficiency, they need reliable
feeding recommendations based on sound data about animal requirements.
For slurry or liquid manure, an important quality parameter is the dry matter content. Slurry and
liquid manure from pig production are often strongly diluted by washing and flushing water from
animal houses, by leaking drinking nipples and by rainwater getting into the lagoons or tanks.
The consequence is a low nutrient content of the manure and a large quantity that has to be
handled. Recommendations on how to reduce unnecessary water inputs are therefore also an
important requirement.
****************************************************************************
KEY-QUESTION 5: What tools to estimate manure production and quality are available in
Asian and Latin American countries?
****************************************************************************
2.3 MANURE STORAGE AND TREATMENT
To fulfil the principles of good manure and nutrient management there must be sufficient manure
storage capacity (at least for 3-5 months for liquid manure). Thus it is possible to prevent manure
use at times when the soil cannot absorb it or when the development stage of the crops does not
allow its use. The storage facilities must be built in a way to prevent leaching losses and they
must be big enough to prevent overflow during winter or rainy season. If there is no natural clay
layer that prevents leaching, lagoons for liquid manure must therefore be lined with plastic or
concrete.
Manure treatment is often seen as an important option to reduce environmental impacts of
manure management. Manure treatment can reduce the amount of organic substance, dry mater,
nitrogen and pathogens in the manure and the emission of odour. Nevertheless, it must also be
considered that:

Any treatment will bring additional costs.

Treatment can hardly solve a nutrient surplus problem, at least not at reasonable costs.

Treatment will only be successful if its efficient functioning can be guaranteed under on-farm
conditions and if the capacity of the installation is sufficient for the amount of manure to be
treated.
It will be nearly impossible at reasonable costs to treat manure in such a way that it can be
discharged to watercourses without risk of serious water pollution.
For manure storage and treatment facilities, the economies of scale will clearly favour big farms.
****************************************************************************
HYPOTHESIS 11: Manure treatment can not solve a nutrient surplus problem and it will be
nearly impossible at reasonable costs to treat manure in such a way that it can be discharged to
watercourses without risk of serious water pollution.
KEY-QUESTION 6: What experiences with manure processing and treatment are available from
the various countries?
****************************************************************************
2.4 MANURE UTILISATION
The main options of utilising manure instead of disposing or discharging it are the use as
fertiliser on crop land or as feed for livestock or aquaculture (fish production etc.). From the
ecological viewpoint, the use as feed is an efficient way of saving resources. Attention has to be
given to the prevention of spreading diseases. In the case of aquaculture, the manure utilisation
will have to be organised in a way that does not considerably increase water pollution.
Using manure on cropland means that it has to be transported to the fields and evenly spread. For
solid manure, this is already common practice and the necessary technology exists. For
transporting the liquid manure from the store to the fields on which it is spread the following
options exist:

Canals with sealed bottom and sides if the fields are sufficiently lower than the store.

Fixed installation of tubes or pipes (under or above ground) or temporary installation of tubes
for distances up to about 2 km (without too much difference in altitude).

Tankers, if both the store and the fields are accessible.

Wheel-barrows, small carts or boats (for small farms only).
The appropriate transportation technique will be strongly dependant on the volume (dilution) to
be handled, the distance over which the manure has to be transported, the topography and the
accessibility of the storage and the fields.
For spreading liquid manure on the field the following techniques are possible:

Tankers with splash plate or band application (low emission systems).

Furrow irrigation.

Flexible poly-ethylene (PE) tubes with sprinklers.

High pressure rain-guns.

By hand.
Which of these techniques is appropriate strongly depends on the structure of the farm, the size
and shape of the fields, the crop and the topography.
As observed in the AWI projects, a lot of the manure storage, transport and application
technology used in developed countries will not be appropriate in developing countries due to
technical restrictions (fields too small, accessibility etc.) or for economic reasons. The
appropriate technology must be defined and in many cases developed taking into account
national, regional and farm-specific circumstances.
For manure transport, big farms will be at a disadvantage because they need a bigger radius of
land for spreading the (liquid) manure. Transportation distance for liquid manure could therefore
be one of the most important factors limiting the maximum size of pig farms.
****************************************************************************
HYPOTHESIS 12: A lot of the manure storage, transport and application technology used in
developed countries will not be appropriate in developing countries due to technical and
economic restrictions.
HYPOTHESIS 13: Transportation distance for liquid manure could be one of the most important
factors limiting the maximum size of pig farms.
KEY-QUESTION 7: What manure storage, transport and spreading technologies are available
and applicable in developing countries? What are the most important fields where such
technology must still be developed?
KEY-QUESTION 8: What experience is available in Asian and Latin American countries with
other forms of manure recycling than the use as fertiliser (e.g. use as feed for livestock or fish,
energy production)?
****************************************************************************
3. TOOLS NEEDED TO IMPLEMENT A GOOD MANURE AND NUTRIENT
MANAGEMENT STRATEGY
3.1 DIFFERENCES IN NEEDS BETWEEN STAKEHOLDERS
From the viewpoint of the farmers, there is an urgent need for reliable recommendations on
manure use as fertiliser. As there is not enough relevant experience in this field in most
countries, well-focused experiments should be established without delay. These experiments, as
well as the establishment of demonstration farms or regions trying to implement the AWIconcept, will be an important step in convincing farmers of the feasibility of the proposed
concept.
For bigger farms and for the regional optimisation of manure management, tools will be needed
which help farmers and farm advisors to assess nutrient balances, amount and composition of
manure available, crop nutrient demand etc. Such tools (e.g. models or guide value tables) must
be reliable and easy to use. They should be able to take into account important farm or regionspecific production parameters.
From the viewpoint of policy makers, a model is needed which can assess the nutrient balance
and environmental impact situation at present, for different scenarios of future development and
in the framework of future monitoring programs. For an optimal assessment of the situation it
would probably be best to use the same nutrient flux model mentioned as a need for bigger farms
and to combine it with GIS- technology for further analysis and visualisation of the results. Any
other solution would bear a high risk of misunderstandings because of incongruent results of
different models.
Apart from the tools mentioned above, the success of the AWI strategy will decisively rely on
appropriate policy measures.
****************************************************************************
HYPOTHESIS 14: Reliable planning tools, demonstration experiments and farms and
appropriate policy measures will be decisive for the success of an AWI-strategy.
KEY-QUESTION 9: What tools for good manure and nutrient management are needed in AWI
countries? What tools are already available?
****************************************************************************
3.2 TERMS OF REFERENCE FOR A NUTRIENT FLUX MODEL
Crop and livestock production systems can be very variable, depending on natural conditions
(soil, water household, topography), farm structure and production technique (production
intensity, type and composition of feed etc.). To provide reliable results for different scales of
application or different sites, a nutrient flux model should theoretically be able to take into
account all the factors that might have a significant influence on the results. In practice, the
influencing factors are so numerous and often difficult to quantify, that they must be classified
into the following groups in the process of designing a model:

Factors that can be reliably quantified at the farm level (e.g. breed, production, feed intake
and composition, crop yield).

Factors which can not be quantified for individual farms, but for which reliable regional
recommendations or statistics exist (e.g. nutrient demand of crops).

Factors for which only qualified expert assumptions are possible.

Factors that can not be reliably quantified.
Factors in the first two categories must be integrated as variables that can be filled in by the user.
For factors of the third category, region-specific expert assumptions must be integrated and
factors of the last category must by omitted as long as no more reliable data is available.
Furthermore, model makers must consider that the model should be appropriate for a wide range
of user needs and backgrounds.
Nutrient balance calculations basically compare nutrient inputs with nutrient exports from a farm
or a region. Different levels of detail are possible. For example, inputs and exports can be
assessed in detail based on production parameters or standard values can be used. The
appropriate level usually depends on the availability of input data and the background of the
user. The model should be flexible enough to account for this.
****************************************************************************
HYPOTHESIS 15: Different users (e.g. farmers and policy makers) have different requirements
for a nutrient flux model. Nevertheless, it is advisable that one model is provided which fulfils
the needs of different user groups.
HYPOTHESIS 16: The model used in the AWI project should have the flexibility to use either
farm or region specific input data on production technique or standard values compiled by
national experts.
HYPOTHESIS 17: In the framework of the AWI project, intensive livestock production (pigs
and poultry should be treated in detail, while other livestock categories (e.g. cattle) should only
be included with standard values.
****************************************************************************
3.3 THE AWI NUTRIENT FLUX MODEL
Various manure and nutrient management models exist but many of them focus either on nutrient
fluxes or on amounts of manure to be handled. Furthermore, they do not usually offer the
flexibility of being used by different users, for different applications and at different levels of
detail. A special nutrient flux model was therefore developed for the AWI project. For pig and
poultry production it allows either the use of regional standard values compiled by ational
experts or differentiated input data. For crop production, either crop nutrient demand according
to official recommendations or the actual export based on yield and product composition can be
utilised. The model can be easily adjusted to regional conditions and translated into different
languages. At the moment draft versions of the model exist for Thailand and Jiangsu Province,
China. Adapted versions will be developed for each AWI project country. The draft version for
Jiangsu Province is available at the LEAD Virtual Centre for testing.
MANURE AND NUTRIENT MANAGEMENT
The discussion on Manure and Nutrient Management has been very lively and has brought a lot
of very valuable information. There is still some information which would be grateful to receive
to complete the picture:
 Quantitative data on matter and nutrient fluxes in the different biodigestion systems and other
treatments mentioned (e.g. amount of fresh, dry and organic matter and nutrients fed into the
system and taken out; what size of the system and lagoon do we need for x pigs, what is the
minimum dry matter content for the system to function well). We would be grateful if all of
you that have sent us information on treatment systems
 How is the maure used as feed for cattle, fish etc. (amount interation, other components in
the ration, composition of the manure etc.).
SUMMARY OF THE SESSION ON MANURE AND NUTRIENT MANAGEMENT
Many interesting examples from different countries were presented (e.g. Vietnam, Cambodia,
Philippines, Pakistan, India, Africa, Colombia, Brazil, Hawaii, USA and different European
countries). There seems to be a general agreement that livestock production and especially
intensive livestock production can cause serious environmental pollution and that there is an
urgent need to initiate measures against this. Even though it was mentioned several times that it
would be wrong to believe that only large farms cause pollution, various participants agreed that
the risk in generally higher on large farms because of the high local concentration of manure and
because contrary to small mixed farms a utilisation of the manure within the farm is normally not
possible. Several contributions stressed the fact that it are often the medium- scale and expanding
farmers who cause major pollution hazards because they are short of funds for investment in
manure management and are unaware of the environmental problems caused by their method of
farming. If one large livestock farm has to distribute its manure to a great number of small crop
farms (as is the case for example in the AWI project regions in Thailand and China) it gets
increasingly more difficult and costly to achieve a well dosed distribution.
The attitude toward manure apparently varies a lot, depending on the possible use and personal
perception. It was suggested that we should not talk about waste, but make people realise that
manure is a resource. However, for the present various participants suggested that livestock
farmers would only take the necessary measures for proper manure management if they are
forced to by legislation. Others feared that livestock producers could not bear the costs such
measures would imply. They suggest it would be a better approach to create a demand and a
market for the manure. Nevertheless, while reports from many countries showed that there
usually is a market for solid manure, it remains doubtful if the nutritive value of liquid manure
(especially if it is highly diluted) could ever be significant enough to compensate for the high
costs of storage, transport and spreading, which would be the precondition to build up a demand.
As the experience in the various AWI project shows, even the demand for solid manure is not
primarily driven by the recognition of its nutrient content, but rather by its positive value on soil
structure and nutrient holding capacity. Furthermore, for some high value products public
opinion is against using mineral fertilisers. Consequently, the solid manure currently utilised is
not (fully) accounted for in fertilisation plans and therefore contributes to a surplus of the
nutrient balance. An important factor for the reluctance of accounting for manure nutrients is
their variable and often unknown concentration and their uncertain availability (especially
nitrogen) for crops. Simple but reliable decision support systems might help to overcome this
problem at least in part.
Concerning manure treatment, the discussion mostly focused on anaerobic digestion with biogas
production. Many participants voiced the opinion that manure should always be treated before
being used as fertiliser or in any case before being transported to other farms. Nevertheless there
were also opinions that treatment and especially biogas production also has disadvantages (e.g. if
methane is not burned), that it is too costly if there is no energy demand on the farm itself and,
that according to European experience, biodigesters are not a requirement to achieve a safe
slurry. Economical biogas production was reported from Vietnam where an inexpensive system
for small farms was developed and is now widely used. Two new highly efficient treatment
systems for liquid manure were also reported, but to assess their potential for a wide use under
farm conditions in developing countries further information is still needed. In general, the
discussion showed that for many manure management systems and technology some important
quantitative information on the applicability and efficiency under practical conditions or costs is
often missing. Apart from anaerobic digestion the following interesting solutions for improving
manure and nutrient management were proposed:
 Use of (mainly poultry) manure as feed for other livestock
 Using the effluent from anaerobic digestions to grow aquatic plants or algae which can then
be used as feed.
 Treating solid manure with the larvae of the black soldier fly. These larvae actively consume
and digest the manure and thus strongly reduce the amount of manure and nutrient losses.
The larvae can be used as high protein feed.
 Using solid manure for earth worm production for vermicompost and feed.
 Experimenting with new crops that make efficient use of manure and have a high demand for
nutrients.
 Reducing nutrient excretion of livestock by diets with high digestibility and / or low protein
and phosphorous content.
 Co-composting of manure with urban waste if this has a reasonable quality (free of heavy
metals etc.).
 Reduce the amount of liquid manure and increase its nutrient content by reducing the amount
of water for washing, flushing and cooling and through appropriate housing design and water
management.
 Reducing the amount of rainwater getting in to the slurry (dike around lagoon etc.).
 Mixing organic materials (e.g. rice husks) into the liquid manure to make transport easier.
 Treatment of manure through acidogenic fermentation.
 ransport of liquid manure with pipes, a pipeline systems or covered channels and spreading
by furrow irrigation or sprinkling
The discussion showed that many possible solutions for good manure management exist but that
their adoption will imply a lot more awareness building, education, extension and research. To
support these activities, appropriate tools (decision support tools and technology) and
recommendations are in urgent demand. Various participants see an important role for FAO and
other international organisations to furnish such tools. The discussion also clearly showed that
sustainable solutions must:
1) be well adapted to country, region and farm-specific conditions.
2) lookat the whole context of a farm or a region (livestock production, manure and nutrient
management, crop production, economics etc. rather than at single treatment or spreading
systems or other measures.
3) be based on a good understanding not only of the technological and economic but also of the
socio-economic situation and consequences.
4) Focuson manure types for which a demand exists or can be expected.
It must also be clear that intensive or industrial pig and poultry production and landless urban
based dairy farms must be seen in a totally different perspective than extensive, land-based
production systems with herbivores. In the context of this conference discussion must focus on
AWI of intensive systems. Topics of special interest therefore are spreading of pathogens,
regional and local nutrient balances, socio-economic implications of the further growth of such
systems and possibilities how policy measures can guide future growth of industrialised livestock
production in a sustainable direction. These will be the topics of the oncoming sessions of this
conference.