The purpose of this MScCCAFS thesis is to assess the\nsensitivity of comparative milk footprints from dairy farm systems implementing\nconventional and legume-based animal diets to choice of allocation method. To\ndo this an understanding of and life cycle assessments (LCA), carbon\nfootprinting (CF), allocation methods and system expansion, the Scottish dairy\nindustry and legume-based animal diets is required.<\/p>\n\n\n\n
LCA and CF are methods that allow for\nthe environmental impact of products and supply chains to be investigated. CF\nis a form of LCA and focuses on the environmental impact of Greenhouse gas (GHG)\nwhile LCA looks at more impact categories, for example water use, land use,\nacidification, global warming, eutrophication, acidification, ozone depletion (Broekema & Kramer, 2014; Dalgaard et al., 2008).\nNitrous oxide (N2<\/sub>O) and methane (CH4<\/sub>) are potent GHG that\naccount for a large portion of the agricultural emissions generated (Moumen et al., 2016). They have high global\nwarming potential (GWP), GWP is an index for the amount of warming a gas causes\nover a given period of time. 1kg of methane causes 25 times more warming over a\n100 year period compared to 1kg of CO2 <\/sub>(Raga Mexico et al., 2007). <\/p>\n\n\n\n Allocation methods play an important part in LCA. Allocation\nis the \u201cpartitioning the input or output flows of a process or a product system\nbetween the product system under study and one or more other product systems\u201d (International Organization for Standardization, 2006).\nAllocation methods play a key role when LCA studies are carried out on\nagricultural systems, such as on dairy farms, as there are many co-products\nbeing generated along with the main product milk \u2013 these co-products include\nmeat from culled cows or calves that enter the beef industry, or manure\/slurry.\nThere are different allocation methods available, such as mass, economic,\nenergy and protein based allocation. The different methods of allocation can have\na significant influence on footprint results, so choosing the most suitable\nmethod is critical (Rice et al,. 2017).\nMass and economic allocation were selected for this MScCCAFS thesis project. Mass\nallocation is based on physical properties (mass or volume), dairy farms look\nat the relations between total farm GHG emissions and the total milk and meat\nproduction in kilograms (Kristensen, Mogensen,\nKnudsen, & Hermansen, 2011). Economic allocation also uses physical properties,\nbut the different values of the products are taken into account, so for dairy\nfarms it looks at the total amount of milk and meat produced at a standard unit\nprice (Kristensen et al., 2011).<\/p>\n\n\n\n System expansion is a method used to avoid co-product\nallocation. In system expansion co-products are considered alternatives to\nother products on the global market. As previously stated, a dairy farm\u2019s main\nproduct is milk while the slurry is a co-product. This co-product may also be regarded\nas a \u201cwaste\u201d depending on whether there is a nearby demand (value) for it. The\nslurry from the dairy system can replace fertilizer on the market, which in\nturn means there is an avoided production of fertilizer and thereby a negative\ncontribution to the environmental impact from the lifecycle of dairy (Cederberg & Stadig, 2003; Q-PorkChains, 2017).\nBut it must be noted depending on method used to apply the slurry that emissions\nassociated with application of slurry\/manure can be higher than those associated\nwith application of fertilisers, countering the avoided manufacturing benefit, for\nexample application using a trail shoe instead of a splash plate can see a 20%\nreduction in emissions released (Dowling et\nal.<\/em>, 2008; Laboski et al.<\/em>, 2013). The timing of the\napplication can also have an effect on the emissions, very hot and dry conditions\nlead to higher levels of emissions being released (Laboski et al.<\/em>, 2013).<\/p>\n\n\n\n The Scottish dairy industry is changing, all-year-round indoor\nfeeding and continuous housing are becoming more prevalent in the UK, the\nnumber of farms practising traditional all-summer grazing is decreasing (March et\nal<\/em>., 2014). Legume-based animal diets have the potential to fit well into the\ntraditional summer grazing systems and all-year-round indoor feeding. The\namount of greenhouse gases (GHG) being generated in these systems will vary. Reducing\nemissions and relevant energy flows will be critical for farming in the future (Arag\u00f3n-Durand et al<\/em>., 2018; Food and\nAgriculture Organization, 2015). Climate change is becoming an\never-growing concern and it is causing a push to decarbonise areas such as transport,\nindustry and agriculture. Transport and industry are already moving in this\ndirection, with transport using electric vehicles and industry starting to use\nmore renewable energy sources such as wind turbines to help reduce their carbon\nfootprint. The agricultural sector must also find ways to reduce their\nfootprint (Hoegh-Guldberg et al<\/em>., 2018;\nRogelj et al<\/em>., 2018). <\/p>\n\n\n\n Improving the genetic merit of dairy cows is a way that the\nfootprint of dairy production can be reduced, as a more productive cow will give\nrise to lower emissions per litre of milk or kg of meat produced. Dairy cows\nwith higher genetic merit can have higher milk yields, increased fertility,\nlower calving intervals, increased longevity of the cow within the herd, lower\nfeed requirement, less emission production during rumination (Byskov et al<\/em>., 2017; Crowley et al<\/em>.,\n2017; Hurley et al<\/em>., 2018). Improving these traits through genetics\ncan reduce the amount of emissions produced by dairy cows in Scotland (Ross et al<\/em>., 2014; Vellinga et al<\/em>., 2018).\nThe progression of genetics within the Scottish dairy sector has been steadily\nimproving since the 1980\u2019s (Wall, 2018). This\nmeans the chance and system to reduce dairy footprints through genetics is\nalready in place, and the there is large potential to continue to reduce the\nemissions through genetics.<\/p>\n","protected":false},"excerpt":{"rendered":" The purpose of this MScCCAFS thesis is to assess the sensitivity of comparative milk footprints from dairy farm systems implementing conventional and legume-based animal diets to choice of allocation method…. 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