Degradation of Fibre and Non-fibre Fractions During Anaerobic Digestion in Silages of Maize, Sunflower and Sorghum-Sudangrass of Different Maturities

This study investigated the temporal dynamics of the degradation of organic matter (OM), fibre, protein and remaining organic constituents during anaerobic digestion of silages from maize, sunflower and sorghum-sudangrass that were harvested at different maturity stages. The tests were conducted using an in sacco method in 20 l digesters. The degradation kinetics of fibres showed some similarity for maize and sorghum-sudangrass with a continuous progress, whereas in sunflower it developed with a strong degradation right after incubation to reach a quasi-constant level for the rest of the 35 days lasting fermentation time. The degradation process for crude protein was usually intense from the very beginning and levelled off after only 5 days. Methane yield after 35 days amounted to 358, 278, and 320 l(N) CH4/kg OM for maize, sunflower and sorghum-sudangrass respectively but could not be predicted with high accuracy by regression models based on organic constituents.