Calculate the ratio of net energy available for growth in the diet (REG – Net Energy for Growth / Digestible Energy)

Calculates the ratio of net energy available for growth to digestible energy consumed (fraction), which represents the efficiency with which digestible energy in the diet is converted into net energy retained as body tissue.

Usage

calc_reg_growth(species_short, ration_digestibility_fraction = 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

ration_digestibility_fraction

Numeric. Average digestibility of the feed ration, expressed as ratio of digestible to gross energy content (fraction).

Value

Numeric. Ratio of net energy available for growth in the diet to digestible energy consumed (fraction).

Details

This component follows the IPCC Tier 2 partitioning approach and returns REG for ruminants (CTL, BFL, SHP, GTS) as: $$ net\_energy\_growth\_digestible\_energy\_ratio = 1.164 - 0.005160 \times diet\_digestibility\_fraction \times 100 + 0.00001308 \times (diet\_digestibility\_fraction \times 100)^2 - \frac{37.4}{diet\_digestibility\_fraction \times 100} $$

For Other species REG is not applicable and the function returns NA_real_.

This function is part of the run_metabolic_energy_req_module().

References

Gibbs M.J., Johnson D.E. (1993) Livestock Emissions. In: International Methane Emissions. Washington, D.C., U.S.A: US Environmental Protection Agency, Climate Change Division.

IPCC. (2019). 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management, Equation 10.15.

IPCC. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Chapter 10: Emissions from Livestock and Manure Management, Equation 10.15.