Greenhouse gas emission of Canadian cow-calf operations: A whole-farm assessment of 295 farms

The Canadian beef industry is a major contributor of greenhouse gas (GHG) emissions from the agricultural sector. The industry is diverse geographically as well as in operation scale and management, suggesting there may be opportunities to reduce GHG emissions through identification and adoption of selected management practices. The objectives of the study were to: i) estimate variation in emission intensity [total farm GHG emissions (kg carbon dioxide equivalents, CO2e) per kg total live weight (LW) sold] among cow-calf farms by categorizing farms into low-and high-emitting groups, and ii) identify management attributes that significantly impact whole-farm GHG emissions. Farm survey data from 295 beef cow-calf farms were used to estimate farm GHG emissions using a whole-farm model, Holos. Emission estimates included methane from enteric fermentation and manure, nitrous oxide from soils (crop, forage, pasture, range) and manure, and carbon dioxide (CO2) from on-farm energy use and production of farm inputs. Farm boundary was delineated at the farm-gate and included all the processes of the farm until weaned calves and culled cows left the farm. Overall, our study indicated that large variation in emission intensity existed among cow-calf operations, regardless of the size (expressed as number of cows or land area) or location of the farms in Canada. Emission intensity averaged 23.9 (range of 16.3 to 37.8) kg CO2e kg− 1 LW sold and 2178 (range of 266 to 9782) kg CO2e ha− 1. Most of the total farm emissions were associated with enteric fermentation (65%) and manure storage (23%). The quartile of low-emitting farms produced an average of 19.9 (range of 16.3 to 21.4) whereas the quartile of high-emitting farms averaged 28.7 (range of 26.3 to 37.8) kg CO2e kg− 1 LW sold. Low-emitter farms produced calves more efficiently (calved earlier in the year, higher calf average daily gain), provided diets with higher digestible energy and crude protein, grew fewer annual crops for feed relative to perennial forage, had higher culling rate, and did not compost manure. Our study indicated that improving management efficiency can reduce average emission intensity by 31% on Canadian cow-calf production systems.