Background
Ireland imports approximately 3 million tonnes of animal feed annually for use as concentrates in our livestock sector. Much of this comes in the form of soy-based ingredients like soybean meal. In recent years, a wider European Union effort has focused on trying to increase the resilience of protein production in Europe. In 2018, the European Commission presented a report on plant proteins in the EU highlighting this effort. Following this extensive discussions have been taking place on the development of an EU Protein Diversification Strategy.
Europe’s protein deficit has resulted in an overdependency of EU member states in importing around 18 million tonnes of soybean to Europe each year. Approximately half the soybean the EU consumes originates in Brazil, with more than a third from Argentina and the United States. While many possibilities for protein crops are being considered, one hidden opportunity is the possibility of improving the utilisation of protein from Europe’s vast grassland which make up one third of the total agricultural land in Europe. This is a particular opportunity for Ireland where grasslands constitute 90% of total agricultural land.
A key strategy for improvement of grassland to increase protein production is the deployment of green biorefineries which can separate the protein of grassland into different products include a press cake forage suitable for ruminants and a leaf protein concentrate (LPC) suitable for monogastric animals like pigs and poultry. This LPC has been demonstrated as a suitable substitute for soybean meal in pig diets through trials in Ireland and Denmark, while the press cake has been demonstrated as a suitable forage for ruminants in trials in Ireland, Denmark and the Netherlands. The results show a clear potential to use of grass-based protein more efficiency to help meet Europe’s (and Ireland’s) protein deficit in a scalable way.
A sustainable soy-based alternative from grass
Recent work is being undertaken within the frame of the InformBio project to evaluate the sustainability of green biorefinery systems for Ireland agriculture. An initial study from Gaffey et al. 2024, conducting used Life Cycle Assessment to analyse the environmental footprint of alternative green biorefinery protein extraction techniques from grasses and legumes and compared the resulting LPC with imported soybean meal. The collaborative study involved researchers from Ireland (MTU, University of Limerick and University of Galway) and Denmark (Aarhus University). In this study, primary data was used from locations in Ireland and Denmark, and the study used economic allocation to attribute the environmental burdens taking into account the different green biorefinery co-products which included press cake (which was assumed to be used as a substitute for silage in animal feed) and brown juice (which was assumed to be used as a feedstock for biogas CHP, creating heat and electrical energy inputs for the process, and a nutrients for recycling back to the farm).
The study also compared different feedstock and processing pathways for comparative purposes. This include a comparison of perennial ryegrass versus a grass-clover mixture as feedstock inputs, and a comparison between conventional maceration (pre-treatment) with a novel disruptive maceration process which was generated a higher yield of juice and protein from fresh grass.
The study found that overall LPC generates a significantly low share of burdens compared with soybean meal on a DM crude protein basis (1 tonne DM of crude protein in concentrate was used as the functional unit to compare LPC and Soybean meal). While the estimated climate change footprint of soybean meal was 3780 kg CO2 eq., the footprint of LPC ranged between 560-1650 kg CO2 eq. per tonne DM of crude protein in concentrate. The scenario combined grass-clover as feedstock input with disruptive maceration technology was the lowest emitting scenario due mainly to lower fertiliser input during cultivation, lower land requirement to meet crude protein target, and greater energy self-sufficiency through utilisation of process residues to produce heat and electricity. This reduction in impact comparing LPC with soybean was seen commonly across diverse environmental impact categories, including acidification, eutrophication and non-renewable energy use.
Future improvement opportunities
The study is import in that it complements previous technical work assessing LPC as a feedstock for monogastrics, with a demonstration of improved environmental performance which demonstrates its capacity to help Ireland and Europe to become more resilient in terms of its animal feed requirements, whilst also offering significant mitigation opportunities, since the cultivation and transport of soy usually comes with significant environmental consequents.
Build on the above research work is being undertaken currently to further optimise these green biorefinery value chains to improve their economic and environmental viability. This includes the potential to fractionate LPC into components suitable animal feed (green protein) and components suitable for human consumption (human protein). Other high value ingredients including prebiotic ingredients from grass are also possible (Menon et al., 2024).
Green biorefinery has been demonstrated through a variety of Irish-based projects such as Biorefinery Glas, Farm Zero C and Farm4More. Work is being undertaken to scale these technologies in Ireland.
