Skip to contents

Calculate metabolic energy requirements for work

Source: R/core_model_metabolic_energy_req.R
calc_metabolic_energy_req_work.Rd

Calculates the energy requirement for work (MJ/head/day), defined as the additional energy required to support draught power and work-related physical activity.

Usage

calc_metabolic_energy_req_work(
  species_short,
  cohort_short,
  metabolic_energy_req_maintenance = NA_real_,
  draught_work_hours_female = NA_real_,
  draught_work_hours_male = NA_real_,
  draught_fraction_female = NA_real_,
  draught_fraction_male = 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)

metabolic_energy_req_maintenance

Numeric. Energy required for maintenance, defined as the amount of energy needed to keep the animal at equilibrium such that body energy is neither gained nor lost. Expressed as net energy for CTL, BFL, SHP, GTS and as metabolizable energy for CML and PGS (MJ/head/day).

draught_work_hours_female

Numeric. Average daily working time per adult female (hours/head/day). Required only for species = CML, CTL and BFL.

draught_work_hours_male

Numeric. Average daily working time per adult male (hours/head/day). Required only for species = CML, CTL and BFL.

draught_fraction_female

Numeric. Fraction of adult females involved in draught work (fraction). Required only for species = CML, CTL and BFL.

draught_fraction_male

Numeric. Fraction of adult males involved in draught work (fraction). Required only for species = CML, CTL and BFL.

Value

Numeric. Energy required for work, used to estimate the energy required for draught power for CTL, BFL and CML (MJ/head/day). Assumed to be 0 for other species. Expressed as net energy for CTL, BFL, SHP, GTS and as metabolizable energy for CML and PGS.

Details

This approach follows the IPCC Tier 2 partitioning method and applies species-specific coefficients for draught work.

This energy component is calculated only for adult cohorts ( FA and MA) of draught-capable species (CTL, BFL, and CML). It is scaled by the fraction of adult animals involved in draught work (draught_fraction_female, draught_fraction_male) and their average daily working time (draught_work_hours_female, draught_work_hours_male).

Species-specific approach:

CTL and BFL - (Bamualim & Kartiarso, 1985; IPCC, 2006; IPCC 2019). Draught work energy is expressed as a proportion of net energy for maintenance:

\( metabolic\_energy\_req\_work = 0.1 \times metabolic\_energy\_req\_maintenance \times work\_hours \times draught\_fraction \)

where:

  • \(metabolic\_energy\_req\_maintenance\) is net energy required for maintenance (MJ/head/day) and can be calculated using calc_metabolic_energy_req_maintenance(),

  • \(0.1\) represents a 10% increase in maintenance energy per hour of work,

  • \(work\_hours\) is the mean number of hours worked per animal per day - draught_work_hours_female (for FA) and draught_work_hours_male (for MA) and,

  • \(draught\_fraction\) is the fraction of adult animals performing draught work - draught_fraction_female (for FA) and draught_fraction_male (for MA)

CML - (Wilson, 1989) Draught work energy is calculated using a fixed metabolizable energy cost per hour of work:

$$ metabolic\_energy\_req\_work = 4 \times work\_hours \times draught\_fraction $$

where:

  • \(4\) is the metabolizable energy requirement for draught work (MJ/hour),

  • \(work\_hours\) is the mean number of hours worked per animal per day - draught_work_hours_female (for FA) and draught_work_hours_male (for MA) and,

  • \(draught\_fraction\) is the fraction of adult animals performing draught work - draught_fraction_female (for FA) and draught_fraction_male (for MA)

This function is part of the run_metabolic_energy_req_module().

References

Bamualim A., Kartiarso (1985). Nutrition of draught animals with special reference to Indonesia. In: Draught Animal Power for Production. Australian Centre for International agricultural Research (ACIAR), Proceedings Series No. 10, ed. JW Copland. Canberra, A.C.T., Australia: ACIAR.

IPCC. (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management, Equation 10.11.

IPCC. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management, Equation 10.11.

Wilson (1989). The nutritional requirements of camel. In: Tisserand J.-L. (ed.). Séminaire sur la digestion, la nutrition et l'alimentation du dromadaire. Zaragoza : CIHEAM. (1989). p. 171-179 (Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 2)

See also

run_metabolic_energy_req_module, calc_metabolic_energy_req_maintenance