Comparative life cycle assessment (LCA) of pork using different protein sources in pig feed

Feed production is the main contributor to a subset of environmental impacts of pork production. In this context, this study is concerned with the substitution of soy products in pig diets in order to reduce these impacts. The aim of this study was to assess three alternative diets in gestating and lactating sows as well as growing and finishing pigs in order to reduce the amount of soy products used as ingredients. In the three alternative scenarios soy proteins were compensated for by either using a combination of different feedstuffs (e.g. rapeseed meal, fava beans, and synthetic amino acids) (LOW), maximising the use of legumes (mainly fava beans) (LEG) and increasing the amount of synthetic amino acids (AA). These alternative scenarios were compared with standard diets (ST) and formulated in order to reduce the crude-protein content of the diet while maintaining the same performance of the pigs. Each of the resulting 16 diets was then assessed with respect to global warming, eutrophication, acidification, and land use, both when accounting and not accounting for emissions due to land use change. The analysis per kilogram of feed showed that the ST diets performed best with regard to global warming, eutrophication, and acidification. When emissions from land use and land use change were added, ST and AA diets appeared to have the least impact. In contrast, the assessment of scenarios per kilogram of pork highlighted that the AA scenario contributed the least in all impact categories. In conclusion, it is possible to partly replace soybean products by using synthetic amino acids in order to minimise the environmental impacts of the pork supply chain.