Green biorefinery feed protein - influence of harvest method and post-harvest time on protein extraction yield

Green biomass of perennial forage grass and legumes has a great potential as resource for local production of protein feed for monogastric livestock in temperate regions. The extraction of leaf protein involves maceration and pressing of the biomass producing a fibrous pulp with potential as cattle feed, and a nutritional juice containing the soluble leaf proteins (30-60% of the total protein). The latter is coagulated and dewatered producing a storable protein feed concentrate. However, to achieve a high protein extraction yield, the green biomass has to be processed fresh and at low DM, thus the logistics and handling before extraction is of crucial importance to the overall yield and protein quality. Present study included two biomasses, ryegrass (Lolium perenne L.) and white clover (Trifolium repense L.), and tested the effect of two different harvest methods and the effect of post-harvest time. The biomass were harvested by laying in swath and after that either piling the swath directly onto a truck or chopping it before piling, as it is done for silage. The biomass was then processed straight after harvest or left in the pile for 4, 24, and 48 hours. The results that will be presented at the conference will have a significant impact on the management of green biomass for protein extraction, and are an important part of initial laboratory studies that will lead to a pilot scale testing facility at Aarhus University with start-up summer 2015.