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Calculate fibre energy requirements (for biophysical allocation)

Source: R/core_model_allocation.R
calc_fibre_allocation_energy.Rd

Calculates the energy required for fibre production over the assessment period (MJ/cohort/assessment period), based on the daily energy requirement for fibre production, cohort size, and assessment duration.

Usage

calc_fibre_allocation_energy(
  species_short,
  cohort_stock_size = NA_real_,
  metabolic_energy_req_fibre_production = NA_real_,
  ratio_me_to_ne = NA_real_,
  simulation_duration = NA_real_
)

Arguments

species_short

Character. Code identifying the livestock species. Supported values include:

  • PGS: pigs

  • CML: camels

  • CTL: cattle

  • BFL: buffalo

  • SHP: sheep

  • GTS: goats

cohort_stock_size

Numeric. Average population size in each of the 6 sex–age cohorts (# heads). (cohorts=FJ, FS, FA, MJ, MS, MA).

metabolic_energy_req_fibre_production

Numeric. Energy required for the synthesis of fibre for SHP, GTS and CML. Assumed to be 0 for other species. (MJ/head/day). Expressed as net energy for SHP and GTS and as metabolizable energy for CML.

ratio_me_to_ne

Numeric. Ratio of metabolizable energy converted to net energy (fraction). Used for species_short = CML.

simulation_duration

Numeric. Length of the assessment period (days).

Value

Numeric. Energy required to produce all fibre output by cohort (MJ/cohort/assessment period). Non-zero values are expected only for fibre-producing species (CML, SHP, GTS) and applicable cohorts ("FA", "FS", "MA", "MS").

Details

This function provides the fibre-related energy term used in a biophysical allocation framework to apportion emissions between milk and other co-products in multifunctional livestock production systems.

The approach implements the IDF (2022) standard, adapted from Thoma and Nemecek (2020), and is consistent with FAO LEAP livestock LCA guidelines (FAO, 2016a, 2016b, 2016c) and with ISO 14044:2006 (Section 4.3.4.2, Step 2).

In accordance with ISO 14044:2006 (Section 4.3.4.2, Step 2), known processing or biophysical relationships may be used to assign shared inputs and outputs of a single production unit to individual products or sub-units. In livestock systems, this includes apportioning shared feed and energy use according to physiological energy requirements (e.g., net energy for lactation, growth, etc.). If the resulting process remains multifunctional, these energy terms may subsequently be used to derive allocation factors among co-products.

Total fibre-related energy over the assessment period is computed for fibre-producing species (CML, SHP, GTS) and applicable cohorts ("FA", "FS", "MA", "MS").

The fibre_allocation_energy is calculated as follows:

\(energy\_allocation\_fibre = \frac{energy\_requirement\_fibre\_production}{ratio\_me\_to\_ne} \times simulation\_duration \times cohort\_stock\_size\)

for camels (CML), and:

\(energy\_allocation\_fibre = energy\_requirement\_fibre\_production \times simulation\_duration \times cohort\_stock\_size\)

for sheep (SHP) and goats (GTS).

where metabolic_energy_req_fibre_production can be computed using calc_metabolic_energy_req_fibre (see also run_metabolic_energy_req_module).

This function is part of the run_allocation_module().

References

ISO. (2006). Environmental management — Life cycle assessment — Requirements and guidelines (ISO 14044:2006). International Organization for Standardization, Geneva.

IDF. (2022). The IDF Global Carbon Footprint Standard for the Dairy Sector. Bulletin of the IDF No. 520/2022. International Dairy Federation, Brussels.

Thoma, G., and Nemecek, T. (2020). Allocation between milk and meat in dairy LCA: Critical discussion of the IDF’s standard methodology. In Proceedings of the 12th International Conference on Life Cycle Assessment of Food (LCAFood 2020) (pp. 83–89), 13–16 October, Berlin, Germany.

FAO. (2016a). Environmental performance of large ruminant supply chains: Guidelines for assessment. Livestock Environmental Assessment and Performance (LEAP) Partnership. FAO, Rome, Italy.

FAO. (2016b). Greenhouse gas emissions and fossil energy use from small ruminant supply chains: Guidelines for assessment. Livestock Environmental Assessment and Performance (LEAP) Partnership. FAO, Rome, Italy.

FAO. (2016c). Greenhouse gas emissions and fossil energy use from poultry supply chains: Guidelines for assessment. Livestock Environmental Assessment and Performance (LEAP) Partnership. FAO, Rome, Italy.

See also

run_allocation_module, calc_metabolic_energy_req_fibre, run_metabolic_energy_req_module