The carbon footprint of beef cattle is presented for Canada, The United States, The European Union, Australia and Brazil. The values ranged between 8 and 22 kg CO₂e per kg of live weight (LW) depending on the type of farming system, the location, the year, the type of management practices, the allocation, as well as the boundaries of the study. Substantial reductions have been observed for most of these countries in the last thirty years. For instance, in Canada the mean carbon footprint of beef cattle at the exit gate of the farm decreased from 18.2 kg CO₂e per kg LW in 1981 to 9.5 kg CO₂e per kg LW in 2006 mainly because of improved genetics, better diets, and more sustainable land management practices. Cattle production results in products other than meat, such as hides, offal and products for rendering plants; hence the environmental burden must be distributed between these useful products. In order to do this, the cattle carbon footprint needs to be reported in kg of CO₂e per kg of product. For example, in Canada in 2006, on a mass basis, the carbon footprint of cattle by-products at the exit gate of the slaughterhouse was 12.9 kg CO₂e per kg of product. Based on an economic allocation, the carbon footprints of meat (primal cuts), hide, offal and fat, bones and other products for rendering were 19.6, 12.3, 7 and 2 kg CO₂e per kg of product, respectively.

To assess tradeoffs between environmental sustainability and changes in food production on agricultural land in Canada the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES) was developed. It incorporates four livestock specific GHG assessments in a single model. To demonstrate the application of ULICEES, 10% of beef cattle protein production was assumed to be displaced with an equivalent amount of pork protein. Without accounting for the loss of soil carbon, this 10% shift reduced GHG emissions by 2.5 TgCO₂e y⁻¹. The payback period was defined as the number of years required for a GHG reduction to equal soil carbon lost from the associated land use shift. A payback period that is shorter than 40 years represents a net long term decrease in GHG emissions. Displacing beef cattle with hogs resulted in a surplus area of forage. When this residual land was left in ungrazed perennial forage, the payback periods were less than 4 years and when it was reseeded to annual crops, they were equal to or less than 40 years. They were generally greater than 40 years when this land was used to raise cattle. Agricultural GHG mitigation policies will inevitably involve a trade-off between production, land use and GHG emission reduction. ULICEES is a model that can objectively assess these trade-offs for Canadian agriculture.

Although the demand on agriculture to produce food could double by 2050, changing diets will expand the global demand for protein even faster. Canadian livestock producers will likely expand in response to this market opportunity. Because of the high greenhouse gas (GHG) emissions from animal protein production, the portion of this protein demand that can be met by pulse crops must be considered. The protein basis for GHG emission intensity was assessed for 2006 using a multi-commodity GHG emissions inventory model. Because arable land is required for other agricultural products, protein production and GHG emissions were also assessed on the basis of the land use. GHG emissions per unit of protein are one or two orders of magnitude higher for protein from livestock, particularly ruminants, than for protein from pulses. The protein production from pulses was moderately higher per unit of land than the protein from livestock. This difference was greater when soybeans were the only pulse in the comparison. Protein from livestock, especially ruminants, resulted in much higher GHG emissions per unit of land than the protein from pulses. A shift towards more protein from pulses could assure a better global protein supply and reduce GHG emissions associated with that supply.