Effects of cellulase or lactic acid bacteria on silage fermentation and in vitro gas production of several morphological fractions of maize stover

This experiment examined effects of adding cellulase or lactic acid bacteria (LAB) on silage fermentation and in vitro gas production of various morphological fractions of maize stover. Maize stover was separated into leaf blade, leaf sheath and whole stem, or kept as whole maize stover, and each fraction was ensiled for 60 days with 0, 10 and 20 ml of cellulase or 0, 105 and 2 × 105 cfu/g LAB, per kilogram of wilted material. The silage was sampled for measurement of pH, lactic acid, chemical composition and in vitro gas production. Before ensiling there were substantial variations in chemical composition between the fractions of maize stover (P<0.001). Leaf blade had the highest content of crude protein (CP), but the lowest contents of neutral detergent fiber (aNDF) and water soluble carbohydrates (WSC). Leaf sheath had the highest aNDF content but the lowest contents of CP and neutral detergent soluble, and the whole stem fraction had the highest WSC content. Lactic acid concentrations in untreated silage were in the order: whole stem > whole maize stover > leaf sheath > leaf blade. Losses of dry matter (DM) and aNDF were in the order: leaf blade > leaf sheath > whole maize stover > whole stem. Addition of either cellulase or LAB accelerated (P<0.05) degradation of WSC, increased lactic acid concentrations of the silage, reduced losses of DM, aNDF and CP during ensiling and enhanced the metabolizable energy level as estimated from 26 h gas production. Effects depended on the level of additives. To improve silage quality, a cellulase preparation was more effective on maize stover fractions that contain high aNDF and acid detergent fiber than LAB, while LAB was better than cellulase for the fraction with high WSC content than cellulase.