Factors Influencing Silage Quality and Their Implications for Management

Abstract Preservation of crop quality, DM, and energy in the silo requires that plant respiration, plant proteolytic activity, clostridial activity, and aerobic microbial growth be limited. A critical mechanism for limiting these processes is quick attainment and maintenance of anaerobic conditions in the silo. If the crop is wilted to greater than 55% DM, fermentation of the crop plays a minor role in making quality silage. For wetter crops, a rapid decline in pH is essential. Dropping pH by fermentation requires an anaerobic environment, adequate substrate, and sufficient numbers of lactic acid bacteria. The substrate required for good fermentation is dependent on the crop, increasing with buffering capacity and moisture content. Approximately 10 8 lactic acid bacteria per gram of crop are required before a noticeable drop in pH occurs. Because this concentration is much greater than that supplied by inoculants, the most important characteristic for an inoculant is fast growth rate in the silo environment. Also, an inoculant's success depends on adequate substrate and its population relative to the natural one. Dropping pH by acids effects an immediate pH change, which is beneficial in preserving protein nitrogen. However, this advantage must be balanced against its cost and safety in handling.