A review of the Life Cycle Assessment of off-grazing technologies

Life Cycle Assessment (LCA) is a systems approach to assess the environmental impacts during the life cycle of products and services (ISO 2006). LCA can be particularly useful in assessing pollution swapping and trade-offs along the product’s life cycle or between different environmental impacts (including climate change from greenhouse gas (GHG) emissions). Another benefit of applying LCA is that insight can be gained into the overall environmental impact when farm practices change or mitigation options are implemented. An LCA study can be conducted across various stages in the production chain of a product or products. For example, pasture-to-plate studies investigate the whole production chain, from the production of fertilisers to the preparation of food by the consumer. Alternatively, a cradle-to-farm gate study can be performed to investigate the total GHG emissions (or carbon footprint) of products up to the farm gate as a specific point in the production chain. Most published research using LCA methodology for estimating the carbon footprint of dairy products have been limited to the cradle-to-farm-gate stages, partly because these stages are the dominant contributor to the carbon footprint over the whole life cycle of dairy products (e.g., Thoma et al. 2013). LCA can be used to assess the carbon footprint of off-grazing systems while accounting for the changes that occur as a result of the implementation of these off-grazing technologies (Figure 7.1). Examples of these changes are the use of different feeds, which vary in their carbon footprint, and a reduced use of artificial fertiliser due to greater control over the storage and release of animal effluent onto land. Unfortunately, there have been limited studies that have applied LCA to evaluate off-grazing technologies in pastoral farming systems dominated by grazing of pastures. This is most relevant in New Zealand and other temperate countries such as Australia, Chile, Ireland, Uruguay and South Africa. In contrast, numerous studies have applied LCA in intensive dairy systems dominated by animal housing. In this review, we will focus first on the LCA studies of off-grazing technologies used in pastoral farming systems Secondly, we will review published LCA studies of intensive dairy systems to gain an insight into the hotspots of the carbon footprint of animal housing systems.