This code is a complete summary of the GAMS script used to run the optimization model described in the paper Hawkins et al. (2015)

Hawkins, J., Weersink, A., Wagner-Riddle, C., & Fox, G. (2015). Optimizing ration formulation as a strategy for greenhouse gas mitigation in intensive dairy production systems. Agricultural Systems, 137, 1–11. doi:10.1016/j.agsy.2015.03.007