A biophysical approach to allocation of life cycle environmental burdens for fluid milk supply chain analysis

Data from 536 United States of America dairy farms were used to test algorithms for milk to beef allocation. A wide range of rations was represented, from pasture-based to large confined animal operations. Variety in the animal classes sent to beef provided a very robust dataset. We report an empirical relationship for the causal allocation ratio (ARc) based on detailed analysis of farm rations, to allocate whole farm emissions between milk and beef: ARc = 1–4.39∙BMR; with BMR defined as the kg beef sold per kg milk sold annually. USA dairy farm green house gas emissions allocated to milk using this approach was, on average, 91.5%, compared with economic (94.4%) and the protein-based (95%) allocation methods. We include an analysis of the allocation between fluid milk and excess cream at the processing plant. This analysis shows 19.8% of the post-farm (after allocation to beef) milk production burden allocated to the excess cream.