Research Partner: University of Bristol / Rothamsted Research
Project Duration: October 2015 – September 2018
PhD Student: Graham McAuliffe
Life cycle analysis (LCA) is a well-established modelling tool for estimating the environmental performance of agricultural systems. Pasture based beef production has the potential to produce a higher quality product in terms of fatty acid and vitamin composition. However, in an LCA context, research to date has not taken into account differences at the nutritional level. In addition, many LCA studies of beef focus on national and regional scales and rely heavily on secondary data.
The North Wyke Farm Platform (NWFP) at Rothamsted Research in Devon is a purpose built facility which aims to identify the most sustainable methods for beef and lamb production.
Three pasture systems have been developed at NWFP:
- Permanent pasture (predominately perennial ryegrass) with no reseeding for the past 15 years
- Perennial ryegrass and white clover (which fixes atmospheric nitrogen (N) reducing the demand for fertiliser N)
- Reseeded swards with the most innovation germplasm (currently high sugar grasses)
The aim of this research is to identify the optimal system for beef production in an environmental, economic and social context using LCA to also include quality of the end product – meat. The NWFP has state-of-the-art automated water quality and greenhouse gas analytical systems in place which will generate LCA data at a level of detail never achieved previously. Fibre analysis on the three swards is also being carried out to determine modified acid detergent fibre (MADF), allowing an estimation of dry matter intake (DMI) for the model. High performance liquid chromatography (HPLC) analysis of meat produced on the systems will be conducted to assess quality and develop novel metrics, such as global warming potential (GWP) per kg fatty acids produced or calories. This research will advance the understanding of sustainable pasture based beef production with practical information.
The overarching aim of this research is to develop novel approaches to reduce uncertainty inherent in life cycle assessment (LCA) of livestock production systems.
Objective 1 (completed):
Quantify the environmental performance of livestock production systems using steady-state herd data that can act as a baseline for methodological comparison.
Objective 2 (completed):
Develop a novel approach to calculate (partial) carbon footprints for each individual animal within the finishing herd.
Objective 3 (completed):
Develop and test new LCA metrics (functional units) that can represent human nutritional value of different livestock production systems.
Objective 4 (completed):
Measure GHG emissions from soils on the NWFP in a static chamber field experiment.
Objective 5 (completed):
Develop a whole system inter-annual carbon footprint using site-specific emissions factors developed from Objective 4 (N2O) and a separate experiment (CH4).
Papers from Objective 1 and Objective 2 have been published in the Journal of Cleaner Production. A paper from Objective 3 has been published in Food and Energy Security. Manuscripts are being finalised from Objectives 4 and 5 and will be submitted to international journals in due course.
Results to date have demonstrated that animals who perform better in terms of average daily gain and time spent on farm tend to have lower carbon footprints than poorly performing animals. This finding paves the way for further applied research surrounding selective genetics and phenotyping. In addition, grass-fed cattle produce much healthier products in terms of fats (particularly omega-3 fatty acids). When meat quality is incorporated into the LCA modelling framework, grass-fed animals tend to generate lower carbon footprints than concentrate-finished animals, given it takes much less meat to produce 1 g omega-3, for example. This provides evidence that a market shift towards quality-based consumption could lower total environmental burdens. Evidence from this study also suggests that small improvements to breeding-herd management, such as optimising stocking rates and numbers of calves per cow, can generate substantial savings to farm-level and system-wide greenhouse gas emissions.