Livestock systems/Data uncertainties limitations: Difference between revisions

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{{ComponentDataUncertaintyAndLimitationsTemplate
{{ComponentDataUncertaintyAndLimitationsTemplate
|Status=On hold
|Reference=FAO, 2012a; Beusen et al., 2008; Bouwman et al., 2005; Seré and Steinfeld, 1996;
|Reference=FAO, 2012; Beusen et al., 2008; Bouwman et al., 2005; Seré and Steinfeld, 1996;  
}}<div class="page_standard">
|Description===Data==
==Data, uncertainty and limitations==
Data on animal stocks, milk production per animal, off-take rates and carcass weights, for the 1970–2005 period, are obtained from the [[FAO]] ([[FAO, 2012]]). Different animal production systems, and their  total population and production have been defined in recent FAO publications ([[Seré and Steinfeld, 1996]]). For ruminants, these production systems include pastoral, mixed and landless production, for various agro-ecological zones. We aggregated the data to two broad groups: pastoral and mixed + landless production systems. The data are provided for 7 large world regions, which we subsequently disaggregated to the level of the 24 world regions in the IMAGE model ([[Bouwman et al., 2005]]). [[Seré and Steinfeld, 1996]] also provided data for the growth in animal populations and the production in each production system.
===Data===
Historical livestock numbers, milk production per animal, off-take rates and carcass weights were obtained from [[FAO]] ([[FAO, 2012a]]). For ruminants, the production systems have been aggregated to two systems: pastoral, and mixed & landless production systems ([[Bouwman et al., 2005]]). For pigs and poultry three systems are distinguished. For pigs these are backyard, intermediate and intensive systems, and for poultry these are backyard, broiler and laying hens systems ([[Lassaletta et al., 2019]]).  
 
==Uncertainties==
==Uncertainties==
There are several uncertainties involved in the calculation of livestock production in the different systems, both for historical years and scenarios. The first uncertainty is the aggregation level on the scale of countries and world regions, whereby all underlying heterogeneity is ignored. A second problem is the use of average data for carcass weight, off-take rate, and milk production for complete animal populations. In reality, animal populations include different age classes, and only part of a population is productive. Some calculations, such as on the energy requirement for maintenance, are a non-linear function of body weight. Using average values, therefore, may not be correct.
There are several uncertainties in the calculation of livestock production in the different systems for historical years and scenarios. The first uncertainty is the aggregation level on the scale of country or world region, which does not take account of underlying heterogeneity. The second uncertainty concerns the use of average data for carcass weight, off-take rate, and milk production for total livestock populations. In reality, livestock populations cover different age classes, and not all animals in a population are productive. Calculations, such as energy requirement for maintenance, are a non-linear function of body weight, and thus use of average values, may lead to distortion. The third uncertainty is associated with livestock numbers. Methodology and frequency of data collection (for example, by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. This uncertainty on livestock numbers affects not only the livestock module, but also all impact IMAGE modules that depend on livestock numbers, such as ammonia emissions ([[Beusen et al., 2008]]).
A further uncertainty is associated with animal stocks. Methodology and frequency of data collection (e.g. by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. Uncertainties in this part of IMAGE as well as in other parts, such as those with respect to ammonia emissions, are strongly related to animal stocks ([[Beusen et al., 2008]]).
 
The main uncertainties in construction scenarios concern agricultural demand ([[Agricultural economy and forestry]]), the distribution of production over the two systems, and production characteristics per system, including feed requirements and feed types.
The main uncertainties in construction scenarios concern agricultural demand ([[Agricultural economy]]), the distribution of production over the two systems, and production characteristics per system, including feed requirements and feed types.  
Limitations
One important limitation is that the development of ruminant livestock system characteristics is purely following a scenario storyline and has no explicit link to the agricultural economy, or for example to land scarcity. This is partly due to the fact that livestock systems in the [[MAGNET model]], so far, have been represented rather weakly, and the model does not include explicit, physically based feed compositions. The two models are coupled only for the calculation of grassland area.  


}}
==Limitations==
The key limitation in the current livestock module is that the ruminant livestock system have a soft linkage to the agricultural economy model MAGNET ([[Agricultural economy]]). Although [[MAGNET model|MAGNET]] has some representation of feed substitution and intensification as a result of land scarcity, and mimics the dynamics described here, there is no explicit representation of livestock systems and physically based feed compositions.
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Latest revision as of 16:27, 26 November 2021

link to framework components overview

Parts of Livestock systems/Data uncertainties limitations

  1. Introduction page
  2. Model description
  3. Policy issues
  4. Data, uncertainty and limitations
  5. Overview of references
Component is implemented in:
Components:
Related IMAGE components
Projects/Applications
Models/Databases
Key publications
References
Livestock systems module in IMAGE 3.0
Flowchart Livestock systems. See also the Input/Output Table on the introduction page.

Data, uncertainty and limitations

Data

Historical livestock numbers, milk production per animal, off-take rates and carcass weights were obtained from FAO (FAO, 2012a). For ruminants, the production systems have been aggregated to two systems: pastoral, and mixed & landless production systems (Bouwman et al., 2005). For pigs and poultry three systems are distinguished. For pigs these are backyard, intermediate and intensive systems, and for poultry these are backyard, broiler and laying hens systems (Lassaletta et al., 2019).

Uncertainties

There are several uncertainties in the calculation of livestock production in the different systems for historical years and scenarios. The first uncertainty is the aggregation level on the scale of country or world region, which does not take account of underlying heterogeneity. The second uncertainty concerns the use of average data for carcass weight, off-take rate, and milk production for total livestock populations. In reality, livestock populations cover different age classes, and not all animals in a population are productive. Calculations, such as energy requirement for maintenance, are a non-linear function of body weight, and thus use of average values, may lead to distortion. The third uncertainty is associated with livestock numbers. Methodology and frequency of data collection (for example, by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. This uncertainty on livestock numbers affects not only the livestock module, but also all impact IMAGE modules that depend on livestock numbers, such as ammonia emissions (Beusen et al., 2008).

The main uncertainties in construction scenarios concern agricultural demand (Agricultural economy), the distribution of production over the two systems, and production characteristics per system, including feed requirements and feed types.

Limitations

The key limitation in the current livestock module is that the ruminant livestock system have a soft linkage to the agricultural economy model MAGNET (Agricultural economy). Although MAGNET has some representation of feed substitution and intensification as a result of land scarcity, and mimics the dynamics described here, there is no explicit representation of livestock systems and physically based feed compositions.

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