Multiscale influence of feedstuff availability on environmental impacts of feed
Résumé
Multi-objective feed formulation (MOF) considers both economic and environmental criteria to decrease, through substitutions between feedstuffs (FS), the environmental impacts of feed with a moderate extra cost. Yet, the question of FS availability on the market is crucial. We studied the effect of MOF in different contexts for pig and broilers feeds, and concentrated feeds of cattle productions, in the North West of France (NW). First, feeds were independently formulated for each production with MOF by defining different lists of available FS and maximum incorporation levels, with a flexible availability of FS (NLIM) or a more constrained one (LIM). Then, all feeds for all productions were then simultaneously optimized (NWF) by considering current FS available volumes and total feed volumes produced in the NW territory. For each context (NLIM, LIM, NWF), Life Cycle Assessment impacts of tons of feed were assessed and compared to those of feeds optimized with least-cost formulation. In NLIM-MOF, Climate Change (CC) was reduced by up to 32, 22, 28 and 23% for pig, broiler, dairy and beef cattle productions respectively. In LIM-MOF, lower reductions were achieved (up to 14, 13, 12 and 11% respectively), due to reduced availability of low-impact FS such as sorghum or pea. In NWF, the global CC impact of feed production in the region is reduced by 7%, with a respective reduction of 5, 8 and 8% for pig, broiler and cattle feeds. Maize used in animal feed is partially replaced by wheat and soybean meal by rapeseed meal. The limited availability of FS leads to a huge competition for the choice of FS between feeds and shows the importance of considering the global livestock sector within a territory. Nevertheless, a significative reduction could be obtained with a limited extra cost (around +2% for NWF).