Age at first calving (farrowing)
The time spent between birth and first calving (farrowing), i.e. the age at which a heifer (gilt) becomes a cow (sow).

Anaerobic digestion
Digestion in the absence of oxygen, i.e. conditions conducive to the conversion of organic carbon into methane (CH4) rather than carbon dioxide (CO2).

Anaerobic digesters
Equipment where anaerobic digestion is operated, i.e. the process of degradation of organic materials by microorganisms in the absence of oxygen, producing CH4, CO2 and other gases as by-products.

Backyard production system
Production that is mainly subsistence-driven or for local markets, displaying animal performance lower than in commercial systems and mostly relying on swill and locally-sourced materials to feed animals (less than 20 percent of purchased concentrate).

Breeding overhead
Animals dedicated to reproduction, rather than to production, i.e. animals necessary to maintain herd/flock size not produce meat or milk.

Chicken reared for meat.

Material produced during the processing (including slaughtering) of a livestock or crop product that is not the primary objective of the production activity (e.g. oil cakes, brans, offal or skins).

Carbon footprint
The total amount of GHG emissions associated with a product along its supply chain; usually expressed in kg or t of carbon dioxide equivalent (CO2-eq.) per unit of output.

CO2-eq emission
The amount of CO2 emissions that would cause the same time integrated radiative forcing, over a given time horizon, as an emitted amount of a mixture of GHGs. It is obtained by multiplying the emission of a GHG by its global warming potential (GWP) for the given time horizon. The CO2 equivalent emission is a standard metric for comparing emissions of different GHGs(IPCC, 2006).

Dairy herd
For the purposes of this assessment, includes all animals in a milk-producing herd: milked animals, replacement stock and surplus calves that are fattened for meat production.

Direct energy
Energy used on-farm for livestock production activities, e.g. for lighting, heating, milking and cooling.

Emission intensity (Ei)
Emissions per unit of output, expressed in kg CO2-eq per unit of output (e.g. kg CO2-eq /kg of egg).

Feed conversion ratio
Measure of the efficiency with which an animal converts feed into tissue, usually expressed in terms of kg of feed per kg of output (e.g. live weight, eggs or protein).

Feed Balancing:
The action of selecting and mixing feed materials (e.g. forages, concentrates, minerals, vitamins, etc.) that are free from deleterious components, to produce an animal diet that matches animal's nutrient requirements as per their physiological stage and production potential

Feed digestibility
Determines the relative amount of ingested feed that is actually absorbed by an animal and therefore the availability of feed energy or nutrients for growth, reproduction etc.

Feed processing
Processes that alter the physical (and sometimes chemical) nature of feed commodities to optimize utilization by animals, e.g. through drying, grinding, cooking and pelleting.

Global warming potential (GWP)
Defined by the Intergovernmental Panel on Climate Change (IPCC) as an indicator that reflects the relative effect of a GHG in terms of climate change considering a fixed time period, such as 100 years, compared with the same mass of carbon dioxide.

Grazing production systems
Livestock production systems in which more than 10 percent of the dry matter fed to animals is farm-produced and in which annual average stocking rates are less than ten livestock units per hectare of agricultural land (Seré and Steinfeld, 1996).

Greenhouse gas
A greenhouse gas (GHG) is a gas that absorbs and emits radiation within the thermal infrared range; this process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozone (O3).

Indirect (or embedded) energy
Energy or emissions arising during the manufacture of farm inputs such as fertilizer or steel.

Industrial production systems
Large-scale and market-oriented livestock production systems that rely on fully enclosed housing, high capital input requirements (including infrastructure, buildings and equipment) and purchased non-local feed or on-farm intensively-produced feed. Industrial systems have high overall herd performances.

Intermediate production systems
Market-oriented livestock production systems that rely on partially enclosed housing, a medium level of capital input requirements and locally-sourced feed materials for 30 to 50 percent of the ration. Intermediate systems have reduced levels of performances compared with industrial systems.

Methane conversion factor
The percentage of manure's maximum methane-producing capacity that is actually achieved during manure management, i.e. part of organic matter actually converted into methane.

Mixed production systems
Livestock production systems in which more than 10 percent of the dry matter fed to livestock comes from crop by-products and/or stubble or more than 10 percent of the value of production comes from non-livestock farming activities (Seré and Steinfeld, 1996).

Natural resource use efficiency
Measured by the ratio between the use of natural resources as input to the production activities and the output from production, e.g. kg of phosphorus used per unit of meat produced, or ha of land mobilized per unit of milk produced.

Amount of output obtained per unit of production factor. In this report, it is used to express amount of product generated par unit of livestock and time, e.g. kg milk per cow per year.

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