Cell wall content and rumen dry matter disappearance of γ-irradiated wood by-products

Spruce sawdust and barks of spruce, pine and larch were irradiated with various doses of γ-rays (0; 0.1; 0.25; 0.5; 1.0 and 2.0 MGy). Cell wall constituents and rumen dry-matter disappearance (incubation time: 48 h) were determined. γ-Irradiation significantly reduced neutral detergent fibre and acid detergent fibre content of all by-products. The crude lignin of the wood by-products was not significantly influenced by γ-irradiation. Rumen dry-matter loss of untreated sawdust was 5.6%, that of barks between 18.2 (pine) and 64.6% (spruce). γ-Irradiation significantly increased rumen dry-matter loss. Increased washout due to solubilization and particle breakdown was mainly responsible for the higher dry-matter losses in the rumen after irradiation. The results do not justify practical use because of the high dose of irradiation required. (author)