Table 1.

Definitions of efficiency of food production from livestock (of any species), as determined by units of comparison and the scale at which comparisons are made.

Efficiency term	Typical metric used	Applicable scales
Feed conversion efficiency	kg feed DM intake/kg product	Individual animal
Feed nitrogen (N) use efficiency	kg N in product/kg feed N intake	Individual animal
Efficiency of human-edible protein production	kg human-edible protein/kg feed protein intake	Individual animal
Efficiency of human-edible food production	kg human-edible product/kg human-edible food	Individual animal, farm
Feed energy use efficiency	MJ product energy/MJ feed energy intake	Individual animal
Land use efficiency	kg product/ha agricultural land kg product/ha land that could be used for human food production	Farm, region, country, global
Farm energy use efficiency	kg product/MJ whole farm energy input	Farm
Emission intensity	g pollutant output/kg product	Individual, farm, region, country, global
Life cycle assessment	kg product/unit of burden	Farm, region, country, global