Ensiling of whole-crop wheat with cellulase-hemicellulase based enzymes. 1. Effect of crop growth stage and enzyme on silage composition and stability

Whole-crop wheat was harvested at the heading, mealy-ripe, medium-dough and hard-dough stages of grain development corresponding to crop dry matter (DM) contents of 310 g DM kg−1, 405 g DM kg−1, 520 g DM kg−1 and 680 g DM kg−1, respectively. Crop from each harvest was either untreated or treated with one of two enzyme additives (Clampzyme or Deezyme) at three application rates of 333, 667 and 1000 ml t−1 DM and 1000, 1334 and 1667 ml t−1 DM (low, medium and high level) for Clampzyme and Deezyme, respectively. Crop from each harvest was ensiled in 5.0 kg quantities in polythene-bag silos, and sealed either immediately or after 24 h. Contents of DM, acid detergent fibre, neutral detergent fibre and in vitro digestible organic matter increased with advancing maturity, but contents of nitrogen, water-soluble carbohydrates and fermentation products decreased. Silage stability, as measured by silo DM loss when exposed, also increased as crops matured. Compared with untreated crop, enzyme treatment increased lactic and acetic acid contents and decreased pH, but these effects were more pronounced in less mature crops. Neither fibre content nor in vitro digestible organic matter content were affected by enzyme treatment; increasing levels of enzyme did not affect silage composition. An interesting finding was that delaying silo sealing by 24 h improved fermentation and improved the aerobic stability of silages. Albeit using small-scale silos, it is concluded that whole-crop wheat may be harvested at DM contents of up to 700 g DM kg−1 (hard-dough stage) and be effectively preserved by ensiling. Addition of cellulase-hemicellulase-based enzymes would enhance fermentation when ensiling less mature (less than 500 g DM kg−1 wheat.