Sustainability of Canadian Dairy Farms

R.C. Martin, M. H. Main, A. H. Fredeen and A. Georgallas
Nova Scotia Agricultural College, Truro, N.S. Canada B2N 5E3

Introduction
Canadian dairy farms have been very productive and a current challenge is to also be environmentally and economically sustainable. A sustainable farm is a healthy system that continues to generate nutritious food while providing profits to the farmer.

Materials and methods
The Atlantic Dairy Sustainability Model (ADSM) assessed sustainability with economic margins ($/year), soil carbon levels (t/ha), soil erosion rates (t/ha/yr), nitrogen use efficiency (kg N output/purchased kg N input), nitrogen leaching (kg N/ha/year), fossil energy use efficiency (MJ output/ purchased MJ input) and greenhouse gas emissions (kg CO2 equivalent / kg milk equivalent). Effects were evaluated on dairy farms with 2 crop input levels (high and low), 4 levels of rolling herd averages (RHA) (5500, 7500, 9000 and 11000 kg milk /cow/year), and 2 pasture use levels (high pasture use and confinement). It was assumed that forage quality was high, pasture management was very good and forages consisted of about 1/3 legume. The ADSM was also used to assess an organic seasonal-grazing dairy system with 280 day synchronized lactation periods, 40% legume content of forage, lower housing and machinery costs and a grazing season of 180 days.

Results and discussion
Results generally indicated that sustainability was optimized under low inputs, high pasture use and RHAs of 5500 and 7500 kg milk/cow/year. When the organic seasonal-grazing system was contrasted to other systems, all sustainability indicators demonstrated an advantage to the organic seasonal system (Table 1). The high input, confinement system was least sustainable, with all indicators. In Atlantic Canada, where land prices are relatively low, revised management and production goals appear to be realistic.

Table 1. Sustainability Profiles for Contrasting Dairy Systems

Conclusion
The organic seasonal-grazing system at 5500 RHA was more sustainable than other systems, according to all sustainability indicators.


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