Samenvatting

The concept of green biorefinery is based on the processing of green biomass into range of innovative products. The basic idea is to use the green biomass in the most optimal way to produce energy and marketable products. Grass silage has versatile properties as raw material for green biorefinery with the advantage of being available all year round in Finland. Usually the biorefinery starts with mechanical separation of liquid and solid fractions, which can be used as animal feeds (solid part for ruminants and liquid part for ruminants but also for monogastric animals). Some studies showed the positive impact of using processed grass silage on milk production. The in vitro approach is a suitable method to evaluate rate of digestibility considering factors such as labour, costs, efficiency and time compared with In vivo experiments which are very time-consuming and expensive, The objective of the current study was to compare fibre composition of intact and processed grass and red clover material and to determine the digestibility of fibre fractions from biorefinery process, using an in vitro gas production method. An in vitro gas production study was conducted at the Natural Resources Institute Finland to estimate the digestion rate of grass silage, fibre fraction and reconstituted silages processed by laboratory (Angel) and farm-scale (Haarslev) twin-screw presses, and red clover silage, fibre and reconstituted silage processed by Angel. Samples were incubated as fresh, but the weights were adjusted to 1 g of dry matter. Samples were incubated in two replicates within run and there were three separated runs that lasted for 72 h each one. A statistical analysis was carried out using SAS program. Results indicated that red clover silage had greater digestion rate than grass silage, while reconstituted red clover silage from Angel press produced less gas than original red clover silage during the incubation time. The reconstitution of the silage after processing with the Angel press for both grass and red clover did not result in any differences in digestion rate when compared to the original silages. We hypothesized that processing of fibre would improve the rate of its digestion, but the current experiment could not confirm it.