LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 1, SESSION A: ANIMAL PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
22. Nitrogen content allocation to handle co-products in livestock
systems – case study on a poultry supply chain
Alexandre Thevenot 1,* , Jonathan Vayssières 2 , Joel Aubin 3 , Emmanuel Tillard 1
1 CIRAD Saint-Pierre, Reunion Island, France, 2 CIRAD Dakar, Senegal, 3 INRA UMR SAS, Rennes,
France, Corresponding author. E-mail: alexandre.thevenot@cirad.fr
In food sectors processes along the life cycle of a product can be multifunctional. ISO standards for Life
Cycle Assessment specify rules in order to allocate the environmental burden between co-products. First
recommendation is to avoid allocation with subdivision or system expansion. However when it is not possible,
emissions and raw materials consumption allocation must reflect the physical relationship between
products. Usually economic, mass or gross energy content allocation rules are used. But several problems
remain for agricultural productions: economic allocation is highly sensitive to market fluctuations and mass
and gross energy content allocations could lead to counter-intuitive results. Co-products may indeed weight
or contain more energy than the product under study itself. For these points, allocation has always been considered
as one of the most controversial issues in LCA and particularly for agricultural systems (Audsley et
al., 1997).
Livestock productions are highly multifunctional (e.g. dairy farming produces milk, meat, and manure). In
industrialised countries, its main function is the provision of proteins for human diet and its major environmental
problems are linked to high nitrogen (N) losses occurring during manure management. For these reasons,
we proposed in this study to compare results obtained with allocation rule based on product’s nitrogen
content with other classical allocation rules (Mass and economic allocation and economic allocation with
system expansion to manure use). Effects of these different allocation rules were applied on a poultry supply
chain in La Réunion (French Tropical Island). Allocation is applied at different production stages: i) breeders
rearing where co-products are breeders and litter, ii) layer production with hatching eggs, cull animals and
unfertilised eggs, iv) broiler production with broiler and litter, v) slaughterhouse vi) Incineration plant with
production of feathers and blood meal as fertiliser and wastes management. For economic allocation we use
the product price at process level. Manure price was estimated by on farm surveys. For system expansion,
poultry litter was in this case replaced by mineral fertiliser which is imported from mainland France over ten
thousand kilometres. The functional unit was defined as one tonne of chicken carcass at slaughterhouse gate.
System boundaries are shown in Fig. 1. LCA was performed using CML 2 Baseline 2000 for Global Warming
(GW), Energy Use (EU), Acidification Potential (AP) and Eutrophication Potential (EP) impact categories,
and Cumulative Energy Demand method v1.08, all implemented in Simapro Software.
Impacts categories were significantly sensitive to the allocation rule (Fig. 2). Economic allocation leads to
higher impact over all categories. System expansion reduced by 10% GW and EU and 5% EP and AP. Nitrogen
content and mass allocation show results around 25% and 30% lower than economic allocation respectively.
Most of differences were observed at farming stage with manure management.
Manure management patterns could differ a lot within a same territory that it is often difficult to establish a
reasonable cost for economic allocation. Mass allocation has to be avoided because litter weight highly depends
on moisture content. System expansion is not recommended in this case because of additionally maritime
transport burden. Nitrogen content allocation seems to be an interesting option for livestock production
environmental assessment and is in the range of other allocation rules. Finally, the choice of allocation rule
for agricultural systems always depends on the manure value in the given system. Using this allocation rule,
poultry litter takes however a high part of environmental burden of meat production, which seems consistent
regarding its high value all over the world.
References
Audsley, A., et al., 1997. Harmonisation of environmental life cycle assessment for agriculture. Final report,
Concerted Action AIR3-CT94-2028. European Commission DG VI, Brussels, Belgium.
Guinée, J.B., et al., 2002. Handbook on Life Cycle Assessment. An Operational Guide to the ISO Standards.
Kluwer Academic Publishers, Dordrecht, The Netherlands.
ISO, 2006. ISO 14040—Environmental management—life cycle assessment—principles and framework.
International Organisation for Standardisation, Geneva.
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