Sustainability of Swath-Grazing Beef Cows in Winter.

Winter grazing is deemed more sustainable than dry lot feeding of gestating beef cows. The objective was to compare entire production and feeding systems for swath-grazed triticale and corn to a dry lot control for cows fed a blend of conserved hay, barley silage and straw. Sustainability was based on a combination of factors including greenhouse gas (GHG) emission, energy and fuel utilization, cost, land use and animal performance. Generally, less energy, fuel and land were required for swath grazing than dry lot and swath grazing cost less, daily, to winter a beef cow or to winter an equal number of cows for an equal number of days.  However, total GHG emissions for triticale and corn were similar to dry lot; corn was lower than triticale. Crop production, feeding operations and input related emissions (non-animal) were lower for swath-grazed compared to dry lot. Enteric methane and manure (methane and nitrous oxide) emissions accounted for 86, 82 and 78% of total emissions for triticale, corn and dry lot systems, respectively. Emissions from energy related sources were lower for swath-grazed compared to dry lot treatments, but represented only 5.5, 7.5 and 12.8% of total system emissions on a CO₂e basis, for triticale, corn and dry lot, respectively. However, triticale yield and carrying capacity were significantly greater than corn and the dry lot feedstuffs. This resulted in land use for triticale and corn of 61 and 82% of the dry lot, respectively. Thus, while GHG emission levels were almost similar for the over wintering systems, land not used in whole-farm feed production by swath grazing higher yielding triticale or corn might be used in increasing whole-farm carbon sequestration, biofuel production or to diversify income. Thus whole-farm sustainability may be improved through swath-grazing a high yielding crop such as triticale through more efficient land use.