Coupling the benefits of grassland crops and green biorefining to produce protein, materials and services for the green transition

Abstract

Compared with annual grain and seed crops, perennial grassland has significantly lower losses of nutrients and low pesticide requirements, whilst also supporting soil carbon build-up. Until now grassland crops have almost exclusively been fed to ruminants and horses. Our experiments on biorefining forages have produced protein of a quality equal to soybean meal. Forage crops can deliver high yields of biomass as well as protein with a well-balanced amino acid profile. In grass crops from unfertilised permanent grassland, focus has to be on the fibre part of the grass due to a low protein yield. With current techniques we have recovered up to 40% of the forage protein into a protein concentrate with around 50% protein. In addition, a fibre fraction containing 15%–18% protein of dry matter can be produced and used as ruminant feed, bioenergy, or further biorefined into chemical building blocks or bio-materials. Our feeding experiments have shown that biorefined grassland protein can provide a substitute for soybean meal for poultry and pigs without negative effects on animal performance. The first industrial scale biorefineries on green biomass for feed and bioenergy are now established in Denmark, although more research is needed in order to evaluate protein quality for both feed and food applications. In addition, a full EFSA approval has to be obtained for the application for food. The green biorefinery concept opens new markets for grassland and opportunities for increasing the grassland area to obtain associated ecosystem services.