Toward climate-smart beef cattle: Quantifying emissions from genetic resources

Animal breeding is a promising strategy to reduce greenhouse gas (GHG) intensities in the beef sector, especially in low-productivity regions like Latin America. Currently, no data on embodied GHG emission for genetic resources exists in life cycle (LC)-based models. A novel biophysical allocation method was developed to derive co-product allocation keys for on-farm burdens of breeding and cow-calf (beef) farms, based on the metabolic energy requirements of reproductive animals at each LC growth stage. GHG intensities were calculated for genetic resources such as semen, embryos, and breeding stock, using high resolution data available from a cattle breeding farm in the Colombian Orinoquia. A novel biophysical approach based on individual animal LC growth stages and metabolizable energy (ME) requirements was developed. Functional units included 1 unit embryo/semen and 1 kg live weight (LW), further distinguished into (i) LWgenetics (determining co-products bred cow, weaned heifer and bull for breeding purposes) and (ii) LWbeef (dependent co-products cull animals and weaned calves). Multifunctionality modeling results were compared with multi-annual cumulative farm GHG emissions and exported LW, economic allocation at animal LC level, along with system expansion and substitution with dependent co-products substituting beef market products. For the first time, genetic resources’ GHG emissions were quantified. GHG intensities for embryos ranged from 0 to 37.5 kg CO2eq unit−1, depending on allocation methods. Results from each allocation method can be used for different purposes, e.g. multi-annual cumulative intensities enable cattle farm benchmarking, while biophysical-based results suit requirements for product environmental footprinting. Including genetic resources as potential beef systems co-products increases accuracy of economic-based intensities, since they can play a major role in farm profitability. The high-quality genetics cattle breed short-cycle Nelore produced LW with up to 17% times lower GHG intensities than the dominant regional breed Brahman demonstrating high potential for food security, improved livelihoods, and GHG mitigation in developing regions. This study introduces a novel biophysical allocation method to quantify embodied GHG emissions of genetic resources like embryos and semen and differentiates LW for beef and genetics markets at farm-gate. This method contributes to a more accurate allocation among cattle farms, recognising the critical value and embodied emissions of intermediate genetic resources as well as final outputs. Future research should focus on representative breeding farms to derive region-specific embodied emission factors of genetic resources.