Greenhouse Gas Emissions From Beef Cattle Overwintering Systems On the Canadian Prairies.

Beef cattle producers on the Canadian prairies have traditionally overwintered cows using intensive management practices, including confinement of cows in dry-lots. In attempts to reduce overwintering costs, producers have begun to utilize extensive overwintering systems including swath, bale or stockpiled-forage grazing. However, little information is available on the environmental implications of these extensive overwintering systems, particularly in terms of greenhouse gas (GHG) emissions. The University of Manitoba is conducting a multidisciplinary research program to examine such beef cattle overwintering systems, including measurements of enteric and soil GHG’s. Deposition of feces and urine by one cow on April 20^th and monitored through to September, 2009, resulted in combined nitrous oxide (N₂O) and CH₄ emissions of 257 and 27 g CO₂ equivalent m^-2, when fed a forage-based diet with and without DDGS (dried distiller’s grains with soluble) supplementation, respectively. Interestingly, DDGS supplementation of the forage-based diet had no significant effect on N₂O or CH₄ emission from patches of simulated bedding pack, which was composed of a mixture of feces, urine, and straw, with feces and urine added at the ratio of feces to urine produced. Research is ongoing to examine soil GHG emissions from feces and urine patches, as well as enteric methane emissions in a bale grazing system compared to a feedlot system overwinter. This systems-based research project will provide information to producers such that they can mitigate GHG emissions from livestock production, as well as policy makers as they seek to provide accurate information for national accounting purposes.