Publisher : Food and Agriculture Organization of the United Nations
Place of publication :
Publication year : 2013
Thematic : Pollution
Language : English
Note
Animal production is a significant source of greenhouse gas (GHG) emissions worldwide.
Depending on the accounting approaches and scope of emissions covered, estimates by various
sources (IPCC, FAO, EPA or others) place livestock contribution to global anthropogenic
GHG emissions at between 7 and 18 percent. The current analysis was conducted to evaluate
the potential of nutritional, manure and animal husbandry practices for mitigating methane
(CH4) and nitrous oxide (N2O) – i.e. non-carbon dioxide (non-CO2) – GHG emissions from livestock
production. These practices were categorized into enteric CH4, manure management
and animal husbandry mitigation practices. Emphasis was placed on enteric CH4 mitigation
practices for ruminant animals (only in vivo studies were considered) and manure mitigation
practices for both ruminant and monogastric species. Over 900 references were reviewed;
and simulation and life cycle assessment analyses were generally excluded.
In evaluating mitigation practices, the use of proper units is critical. Expressing enteric
CH4 energy production on gross energy intake basis, for example, does not accurately reflect
the potential impact of diet quality and composition. Therefore, it is noted that GHG emissions
should be expressed on a digestible energy intake basis or per unit of animal product
(i.e. GHG emission intensity), because this reflects most accurately the effect of a given
mitigation practice on feed intake and the efficiency of animal production.
Enteric CH4 mitigation practices
Increasing forage digestibility and digestible forage intake will generally reduce GHG emissions
from rumen fermentation (and stored manure), when scaled per unit of animal product,
and are highly-recommended mitigation practices. For example, enteric CH4 emissions
may be reduced when corn silage replaces grass silage in the diet. Legume silages may also
have an advantage over grass silage due to their lower fibre content and the additional
benefit of replacing inorganic nitrogen fertilizer. Effective silage preservation will improve
forage quality on the farm and reduce GHG emission intensity. Introduction of legumes into
grass pastures in warm climate regions may offer a mitigation opportunity, although more
research is needed to address the associated agronomic challenges and comparative N2O
emissions with equivalent production levels from nitrogen fertilizer.
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Keywords : Coral reef
Encoded by : Pauline Carmel Joy Eje
