The goal of this activity is to make sure that we all get down to the core findings of the O'Brien's et al., paper. The activity will rely on the photos (below) that illustrates the system's boundaries and main components of a grass-based and confinement dairy system and Table 5 of the O'Brien's paper.  

Instructions:

1. Please locate Table 5 of the O'Brien paper's baseline emissions for the grass-based system (labeled as "Irish"). Match the sources of GHG emissions from Table 5 with the illustration of the grass-based system (photo below).  Are there "important" sources of emission in the Table that are not listed in the photo? How would you improve the illustration (photo) so it includes the main GHG sources (and sink) presented in Table 5?  


2. Please locate Table 5 of the O'Brien paper's baseline emissions for the confinement system (labeled as "US"). Match the sources of GHG emissions from Table 5 with the illustration of the confinement system (photo below).  Are there "important" sources of emission in the Table that are not listed in the photo? How would you improve the illustration (photo) so it includes the main GHG sources (and sink) presented in Table 5? 


3. Notice that all data of Table 5 are expressed as kg of CO2 eq. per ton of ECM (energy corrected milk). Thus comparing numbers in a column gives us the relative importance of each emission source within a system. What are the main sources of emissions from the grass-bases system? what are the main sources of emissions from the confinement system? 


4. What are the main lessons learned from using different co-product allocation method? Please study Figure 1 and be prepare to explain it to the rest of the class


5. What were the main conclusions of the study when comparing grass-based system (Irish) to the confinement system (US)?

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