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Overview of Main Model Elements
Population Model and Methane Emissions Model
This is a brief summary of the Livestock Analysis Model (LAM) Version 1.01, developed by ICF Incorporated. This initial version of the model is available for review and comment. Please provide your comments to the address listed below.
The purpose of the Livestock Analysis Model (LAM)
is to provide a tool for:
- Characterizing cattle and buffalo populations
driven by the supply and demand for livestock products: milk, meat,
and draft power.
- Evaluating the impact of changes in production
characteristics on the population of cattle and buffalo.
- Evaluating baseline and future methane emissions
from cattle and buffalo populations.
Overview of Main
LAM is divided into four main elements as follows:
- Production Targets.
Target levels of production are set for milk, meat, and draft power.
These production targets may be sub-divided into the following sectors:
up to four separate milk herds, two separate draft power herds, and
one meat producing herd. LAM links the sectors together so that the
production of multiple products from one herd (e.g., both milk and meat)
affects the targets for the other herds in all sectors.
- Production Characteristics.
This portion of the model is used to define the production characteristics
of each herd, such as the rate of milk production and mortality rates.
LAM uses these production characteristics to generate the size and composition
of each sector and the overall population of cattle and buffalo.
- Methane Characteristics. This
portion of the model is used to define the characteristics that affect
methane emissions rates. The data required and the method used is based
on the IPCC/OECD Emissions Inventory Guidelines (1994).
This portion of the model presents the results of the calculations,
including descriptions of the livestock populations by sector and methane
LAM is designed to be used as an assessment tool
in the following manner:
- Calibration. Using data on production
levels and animal characteristics for a recent historical year (e.g.,
1990), simulate the population and productivity of the relevant livestock.
The inputs should be checked and verified to ensure that the model produces
a simulation of the livestock population that is consistent with the
data available for the historical year.
- Baseline. Using projected production
levels and animal characteristics for a future year (e.g., 2000), simulate
a baseline of the expected livestock population and methane emissions.
- Simulated Intervention. To simulate
the implications of an intervention, first define how the intervention
would affect production targets, production characteristics, or methane
characteristics. For example, providing improved nutrients to rural
dairy cows would increase milk production per lactation, reduce the
inter-calving interval between lactations, and increase feed digestibility.
The new characteristics are then entered into LAM to simulate the population
and methane emissions that would result from the implementation of the
- Impact. The impact of the intervention
is estimated as the difference between the baseline simulation and the
LAM implements an equilibrium population model
based on the approach in Hallam (1983). The model cannot simulate how
the livestock population will evolve over time as its characteristics
change. Therefore, the year of the assessment must be far enough in the
future to allow the livestock population to adjust to its changed characteristics.
The model is not suitable for simulating livestock populations with rapidly
The estimates produced by LAM are only as good
as the inputs used to describe the livestock populations. Care must be
taken in developing and using the necessary data and checking the data
using a calibration step as discussed above.
LAM is currently under development, and all comments
are welcome regarding its usefulness and suitability as an assessment
tool. Please provide comments to:
Michael J. Gibbs
ICF Consulting Associates, Inc.
10 Universal City Plaza, Suite 2400
Universal City, CA 91608-1097
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