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Reducing Methane Emissions on Dairy Farms

Ireland is committed to reducing national greenhouse gas (GHG) emissions to a level 20 per cent below those of 1990 by the year 2020. The drive for increased milk production, in concert with aims for decreased GHG emissions, poses a significant challenge for the Irish dairy industry.

In an article for TResearch, Teagasc’s science magazine, researchers outline how the adoption of currently available best management practices such as earlier calving, reduced replacement rate; higher stocking rate and longer grazing season provide scope for Irish milk producers to contribute to achieving target reductions in greenhouse gases without necessarily having to limit the overall output of milk solids.

Research designed to reduce the methane emission intensity of milk production has been underway at the Teagasc Animal & Grassland Research and Innovation Centre, Moorepark since 2008. The aim is to investigate practical mitigation options for Irish dairy farmers to drive industry efficiencies. An increased focus on reducing emissions per unit product will result in the maximum reduction in global emissions.

The Teagasc Roadmap for Dairying defined performance improvements in manufacturing milk herds and targets an industry GHG efficiency of 13.53 kg CO2 equivalents per kg milk solids produced by 2018. This compares with a current average estimated at 16.06kg.

Matthew Deighton from the Teagasc Animal & Grassland Research and Innovation Centre, Moorepark, said: “Managing pasture swards to maintain low herbage mass and high leaf to stem ratio may represent a simple, yet important, tool in optimising the GHG efficiency of milk production. Low maturity grass fed to cows resulted in 9.4 per cent less methane gas than a sward grazed at a high maturity. This resulted in a 13.9 per cent reduction in the methane intensity of milk solids production due to a faster grazing rotation.”

A study to compare the relative efficiency of three different breeds, in terms of GHG efficiency, is currently underway. The study will enable comparisons of the enteric methane intensity of milk production from Holstein-Friesian, Jersey and Holstein Friesian x Jersey cows.

The ultimate goal of the research is to develop targeted management strategies that apply currently available resources such as diet, grassland management, and cow genotype to reduce and optimise the methane intensity of milk solids production from pasture. Teagasc is collaborating with researchers in many countries through the EU Joint Programming initiative and the New Zealand led Global Research Alliance on agricultural greenhouse gas mitigation to tackle this problem.