Nitrogen flows in global pork supply chains and potential improvement from feeding swill to pigs

Aimable Uwizeye*, Pierre J. Gerber, Carolyn I. Opio, Giuseppe Tempio, Anne Mottet, Harinder P.S. Makkar, Alessandra Falcucci, Henning Steinfeld, Imke J.M. de Boer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

21 Citations (Scopus)


The global pork sector contributes to food security and supports livelihoods for millions of households but also causes nitrogen (N) pollution. Here we assess N flows, losses, and N use indicators for global pork supply chains, from “cradle-to-primary-processing-gate” and for three production systems: the backyard, intermediate and industrial systems. Subsequently, we evaluate the effects of feeding swill to industrial pigs on N flows and land use. To produce 3.5 Tg N of pork globally, 14.7 Tg N are lost into the environment, of which 68% is lost to watercourses in the form of nitrates and organic N and the reminder emitted to the atmosphere as N-gas (e.g., NH 3 , NOx and N2O). We found that the efficiency of N use, hotspot and magnitude of N losses per unit of area depend chiefly on the region (agro-ecological and economic context), origin of feed, and manure management systems. Swill feeding increases N use efficiency and reduces N losses at the feed production stage. It achieves a saving of 31 Mt of soybeans and 20 Mt of grains on dry matter basis, equivalent to 16 M ha of land used. Its adoption would require innovative policies to preserve food safety and public health. Future research may explore the feasibility and requirements to adopt swill feeding at a country level and may investigate potential impacts on other sustainability objectives.

Original languageEnglish
Pages (from-to)168-179
JournalResources, Conservation and Recycling
Publication statusPublished - Jul 2019


  • Animal production
  • Food wastes
  • Life cycle
  • Livestock
  • Nitrogen use efficiency


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