Livestock systems/Description: Difference between revisions
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|Status=On hold | |Status=On hold | ||
|Reference=Seré and Steinfeld, 1996; | |||
|Description=For each world region, IMAGE distinguishes two livestock production systems, namely pastoral systems and mixed/industrial systems, on the basis of [[FAO]] studies ([[Seré and Steinfeld, 1996]]). In general, pastoral systems are dominated by extensive ruminant production systems. Mixed and industrial systems are more intensive than pastoral ones, and animal husbandry comprises grazing ruminants and monogastrics. For years up to the present, the distribution of livestock production over the two systems, for each IMAGE region, is constructed from historical data, whereas for future years, this depends on the scenario selected. | |||
IMAGE distinguishes five animal categories: beef and dairy cattle (large ruminants), goats and sheep as one group (small ruminants) and pigs and poultry (monogastrics). The numbers of animals and their shares per production system are calculated from data on domestic livestock production, per region, provided by the agricultural economy model (Section 4.2.1) (Figure 4.2.4.1). The number of animals per category is calculated from the total production per region and per animal specific to that region. Stocks of dairy cows ([[POP]]), per country or world region, are obtained from total milk production ([[PROD]]) and the milk production per animal ([[MPH]]): | |||
Animal stocks per region, for the categories beef cattle, pigs, and sheep and goats, is obtained from production and carcass weight ([[CW]]) and off-take rate ([[OR]]): | |||
For production characteristics of milk production per cow, off-take rate, and carcass weight, historical data are obtained from statistics; for future years, their values depend on the scenario considered. | |||
The next step involves the calculation of energy requirements. Energy requirements of dairy cattle are calculated for the energy needed for maintenance (based on body weight), feeding (based on the fraction of grass in feed rations), lactation (based on milk production per cow) and pregnancy (based on the number of calves per year). The amount of dry matter feed is calculated based on the fraction of digestible energy in total energy and the energy content of biomass. | |||
For cattle, feed requirements are based on animal activity and production, whereas for pigs, poultry, sheep and goats, feed requirements are based on Feed Conversion Ratios ([[FCR]]). FCR is the amount of feed (kg dry matter) required to produce one kilogram of milk or meat. For FCR values, historical data are provided up to the present; for future years, FCR values depend on the scenario selected. | |||
For the calculation of the required areas of cropland and grassland (land allocation, Section 4.2.3) are calculated on the basis of feed crop and grass requirements. These in turn are calculated from total feed requirement and diet composition (feed rations). IMAGE distinguishes five feed categories: | |||
# grass, including hay and grass silage; | |||
#food crops and by-products from processing ; | |||
# crop residues remaining in the field after harvesting, and fodder crops; | |||
# animal products; | |||
# foraging, including roadside grazing, scavenging for household waste, and feedstuffs from backyard farming. | |||
Generally, pigs and poultry are purely fed on food crops and their by-products, crop residues and fodder. In pastoral ruminant production systems, grass makes up close to 100% of the feed, except for most developing regions where foraging is assumed to constitute a larger but variable fraction of total feed. Since pigs and poultry are mainly farmed in mixed systems, the contribution of food crops and residues to total feed in these systems is much larger than in pastoral systems. | |||
The required feed crop production is calculated from feed rations, and this information is communicatedpassed on to the agricultural demand model (Section 4.2.1), where it is added to the data on food crops, to obtain total crop production. The share of grass in feed rations determines total grass consumption, which is used to compute the grassland area per world region, based on grazing intensity (Section 4.2.1). | |||
The scenario includes assumptions on milk production per animal for dairy cattle, and carcass weight and off-take rate for beef cattle, pigs, poultry, sheep and goats, and feed conversion rates (FCR) for pigs, poultry, sheep and goats. The changes in these parameters are generally based on the storyline of the scenario, as well as the economic growth scenario. | |||
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Revision as of 10:30, 16 December 2013
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