Waste energy recovery improves price competitiveness of artificial forage from rapeseed straw

Increasingly frequent droughts are causing repeated shortages of forage and are creating imbalances in the livestock economy in many parts of the world. More and more rapeseed is being cultivated for biodiesel production, and its straw has to be removed from fields to minimize disease vectors. Despite good drought resistance, rapeseed straw cannot replace forage because of its poor palatability. Our work objective was to design a pilot plant that would be the first of its kind to turn rapeseed straw into artificial forage on a commercial scale and would enable a first techno-economical assessment. Rapeseed straw is intracellularly disintegrated (by steam explosion technology which uses waste heat from a biogas station to minimize the energy demands) and subsequently enzymatically hydrolysed. A series of in vitro and in vivo analyses of nutrition quality were accompanied by a cost breakdown. The findings obtained in pilot scale dimensions revealed for the first time that rapeseed straw can be turned into artificial forage that has, according to the world standard forage price indicator, a relative feed value rated at the same level as alfalfa hay. However, despite energy savings, the cost of processing makes the cost of the artificial forage about 61% higher than conventional forage of the same quality. On the other hand, the potential for further reduction of production costs has been identified. It can be assumed that the price competitiveness can be achieved during extended periods of drought.