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Calculate meat energy requirements (for biophysical allocation)

Source: R/core_model_allocation.R
calc_meat_allocation_energy.Rd

Calculates the energy required for meat production over the assessment period (MJ/cohort/assessment period), based on total live weight gained by the cohort from birth to slaughter.

Usage

calc_meat_allocation_energy(
  species_short,
  cohort_short,
  meat_production_live_weight_cohort,
  live_weight_cohort_at_slaughter = NA_real_,
  live_weight_at_birth = NA_real_,
  ratio_me_to_ne = 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_short

Character. Sex- and age-specific cohort code describing the production stage of the animals. Supported values include:

  • FA: adult females (from age at first parturition)

  • FS: sub-adult females (from weaning to age at first parturition)

  • FJ: juvenile females (from birth to weaning)

  • MA: adult males (from age at first breeding)

  • MS: sub-adult males (from weaning to age at first breeding)

  • MJ: juvenile males (from birth to weaning)

meat_production_live_weight_cohort

Numeric. Total meat produced as live weight over the assessment period by cohort (kg/cohort/assessment period).

live_weight_cohort_at_slaughter

Numeric. Live weight at slaughter for animals removed from the cohort (kg).

live_weight_at_birth

Numeric. Live weight of the animal at birth (kg).

ratio_me_to_ne

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

Value

Numeric. Energy required by a given sex–age cohort for total meat output by cohort during the assessment period, equal to the energy needed to produce all live-weight gain to reach the target slaughter weight (MJ/cohort/assessment period). For pigs (PGS), the function returns 0 by design.

Details

This function provides the meat-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, known biophysical relationships may be used to assign shared inputs and outputs of a production system to individual products or sub-units. In livestock systems, this includes apportioning shared feed and energy use according to physiological energy requirements such as growth, lactation, and maintenance. If the resulting process remains multifunctional, these energy terms may subsequently be used to derive allocation factors among co-products.

The meat_allocation_energy is calculated as follows:

\(energy\_allocation\_meat = specific\_energy\_meat \times meat\_production\_live\_weight\_cohort\)

where

  • specific_energy_meat is the average energy required to produce one kilogram of live weight, accounting for species- and cohort-specific growth characteristics (MJ/kg live weight).

  • meat_production_live_weight_cohort is the total live weight of animals sold for meat over the assessment period. It can be computed using calc_meat_production (see also run_production_module).

Specific approaches by species:

  • For CTL, BFL, CML, SHP, GTS:

    Growth energy is calculated using species- and cohort-specific biophysical relationships adapted from established growth energy formulations (further details in calc_metabolic_energy_req_growth).

  • For PGS:

    Growth energy is not calculated in this function and 0 is returned. In downstream processing, calc_allocation_shares assigns 100% of the allocation to the edible meat commodity for pig systems.

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_meat_production, run_production_module, calc_allocation_shares