Quantification of methane emissions from Quebec dairy barns: Potential of mitigation by forages and prediction from milk mid-infrared spectra

Anthropogenic greenhouse gas (GHG) emissions are causing global warming. Agriculture is the fourth largest source of GHG in Quebec, accounting for 8% of the province’s total GHG emissions. According to the 2012 Life-Cycle Analysis of the dairy industry in Canada, milk production contributes 13% to the nation’s total agricultural GHG emissions. Methane production during rumen fermentation accounts for half of the GHG emissions from dairy farms. Therefore, there is a pressing need to quantify methane emissions from Quebec dairy farms and to identify mitigation strategies to reduce methane emissions from dairy farms. In this regard, the use of corn silage as the main forage source in the ration is considered a promising strategy for reducing methane emissions, but has not been tested in commercial conditions in Quebec. The main objectives of the project will be: 1) to conduct a survey of methane emissions from Quebec dairy barns, 2) to determine the mitigation potential of corn silage from whole dairy barns, and 3) to develop a method to estimate methane emissions from dairy barns using bulk-tank milk samples mid-infrared spectra. To accomplish these objectives, in collaboration with Valacta, we will select and recruit twelve Quebec dairy farmers with tie-stall barns in the St. Lawrence Lowlands ecoregion that feed either corn silage or legume/grass silage as their main forage. We will directly quantify methane emissions during the spring and fall season in the selected barns using the gold-standard method, which we have recently validated. A survey will be used to collect information on herd, feed and manure management practices from participating dairy farms. Bulk-tank milk samples will be collected from farms during each visit and analyzed by Valacta using midinfrared spectroscopy. The bulk-tank milk spectra will be correlated with measured methane emissions on-farm to assess its predictive potential. The main deliverables to the dairy industry will be: 1) a benchmark for methane emissions from Quebec dairy farms, 2) recommendations for selection of forages to formulate rations with lower CH4 emission intensities under specific production and climatic conditions in Quebec, and 3) assessment of potential indicators in bulk-tank milk samples for routine monitoring of CH4 emissions from dairy barns to support on-farm nutrition management decisions.