Environmental influence of maize substitution by sorghum and diet presentation on goose foie gras production

We studied the environmental consequences of cereal choice and form of presentation of the diet given to geese reared for foie gras production. A cradle-to-gate life cycle assessment of the production of 1 kg of foie gras was used to examine several feeding strategies for substituting maize by sorghum: during the growing–finishing and/or overfeeding period; in a complete pelleted diet or as whole grains. The data come from in-field management practices on representative French goose farms for the breeding, hatching and slaughtering stages of production, and in vivo experiments for the growing–finishing and overfeeding stages. The impact categories were calculated using the CML2 baseline method. Our data showed that the effects of cereal type on the environmental impact of foie gras were dependent on feed level and stage of inclusion. Birds fed exclusively with sorghum during both the growing–finishing period and the overfeeding period had lower environmental impacts than birds fed with maize, for all the potential impacts calculated (e.g. −17% for global warming potential). A diet presented in a simplified form during the growing–finishing period had no effect on foie gras impacts when the cereal used was maize (difference between groups <7%), but increased them when it was sorghum (from +16% for water use to +22% eutrophication and acidification potential), due to higher bird mortality during the overfeeding period. These results suggest that changes in bird feeding practices could contribute to a more environmentally-friendly production system for foie gras if animal performance is note reduced. Hence, substitution of maize by sorghum can lessen the environmental impacts of foie gras production and thus offer a valuable alternative in response to water shortages in southern France, but its use in a simplified form hinges on prior improvement of rearing practices to limit subsequent mortality.